201771010101 白玛次仁 《2018面向对象程序设计(Java)》第十四周学习总结

  

实验十四  Swing图形界面组件

实验时间 2018-11-29

学习总结:

Swing和MVC设计模式

(1)设计模式(Design pattern)是设计者一种流行的 思考设计问题的方法,是一套被反复使用,多数人 知晓的,经过分类编目的,代码设计经验的总结。

(2)模型-视图-控制器设计模式(Model –ViewController )是Java EE平台下创建 Web 应用程序 的重要设计模式。

(3)MVC设计模式 – Model(模型):是程序中用于处理程序数据逻 辑的部分,通常模型负责在数据库中存取数据。

– View(视图):是程序中处理数据显示的部分, 通常视图依据模型存取的数据创建。

– Controller(控制器):是程序中处理用户交互 的部分。通常控制器负责从视图读取数据,控制 用户输入,并向模型发送数据。

(4)Java组件有内容、外观、行为三个主要元素;

 布局管理器

(1)布局管理器是一组类。 – 实现 java.awt.LayoutManager 接口 – 决定容器中组件的位置和大小

Java.awt包中定义了5种布局管理类,每一种布 局管理类对应一种布局策略。

每个容器都有与之相关的默认布局管理器。

(2)5种布局管理器:(1)FlowLayout: 流布局(Applet和Panel的默认 布局管理器) (2)BorderLayout:边框布局( Window、Frame和 Dialog的默认布局管理器) (3)GridLayout: 网格布局 (4)GridBagLayout: 网格组布局 (5)CardLayout :卡片布局

3、GridLayout的构造函数如下:1、GridLayout():生成一个单行单列的网格布局

2、GridLayout(int rows,int cols):生成一个设定行数 和列数的网格布局

3、GridLayout(int rows,int columns,int hgap,int vgap): 可以设置组件之间的水平和垂直间隔

 文本输入

(1)文本域(JTextField) : 用于获取单行文本输入。

(2)文本区(JTextArea)组件可让用户输入多行文 本。生成JTextArea组件对象时,可以指定文本 区的行数和列数: textArea = new JTextArea(8, 40);

  (3)文本区与文本域的异同相同之处: 文本域和文本区组件都可用于获取文本输入。

不同之处:  文本域只能接受单行文本的输入;  文本区能够接受多行文本的输入。

(4)文本区JTextArea的常用API:Java.swing. JTextArea 1.2 – JTextArea(int rows, int cols)

构造一个rows行cols列的文本区对象 – JTextArea(String text,int rows, int cols)

用初始文本构造一个文本区对象 – void setRows(int rows)

设置文本域使用的行数 – void append(String newText)

将给定文本附加到文本区中已有文本的后面 – void setLineWrap(boolean wrap)

打开或关闭换行

(5)标签组件:标签是容纳文本的组件。它们没有任何修饰(如没有边界 ),也不响应用户输入。

 标签的常用用途之一就是标识组件,例如标识文本域。其使用步骤如下:

1. 创建一个JLabel组件

2. 将标签组件放置在距离被标识组件足够近的地方。

(6)密码域:密码域是一种特殊类型的文本域。每个输入的字 符都用回显字符实现,典型的回显字符为*。

– JPassWordField(String text, int columns) 构造一个密码域对象

(7)滚动窗格:

Swing中文本区没有滚动条,若需要滚动条。将文 本区放入一个滚动窗格中即可。

常用API—Java.swing. JScrollPane(教材340页) – JScrollPane(Component c) 在组件c上添加滚动条,返回添加后的组件。

 选择组件

复选框  单选按钮  边框  组合框  滑动条

(1)复选框构造器 1.bold = new JCheckBox("Bold"); 复选框自动地带有表示标签。

2. JCheckBox(String label,Icon icon); 构造带有标签与图标的复选框,默认初始未被选择。

3.JCheckBox(String label,boolean state); 用指定的标签和初始化选择状态构造一个复选框

(2)单选按钮的构造器(教材492页) 1.JRadioButton(String label,Icon icon); 创建一个带标签和图标的单选按钮

2.JRadioButton(String label,boolean state); 用指定的标签和初始化状态构造单选按钮

(3)按钮组:为单选按钮组构造一个ButtonGroup的对象。 然后,再将JRadioButton类型的对象添加到按钮 组中。按钮组负责在新按钮被按下的时,取消前一 个按钮的选择状态。

(4)如果在一个窗口中 有多组复选框或单选按 钮,就需要可视化的形 式指明哪些按钮属于同 一组。Swing提供了一 组很有用的边框

(5)如果有多个选择项,使用单选按钮占据的屏幕空 间太大时,就可以选择组合框。

faceCombo = new JComboBox(); faceCombo.setEditable(true);

让组合框可编辑 faceCombo.addItem("Serif"); faceCombo.insertItemAt("Monospace",0);

增加组合框选项 faceCombo.removeItem("Monospace");

faceCombo.removeItemAt(0); 删除组合框选项内容

(6)组合框的事件监听:为了判断组合框的哪个选项被选择,可通过 事件参数调用getSource方法来得到发送事件的组 合框引用,接着调用getSelectdeItem方法获取当 前选择的选项。

(7)滑动条:滑动条可以让用户从一组离散值中进行选择 ,并且它还允许进行连续值得选择。

 菜单

菜单创建  菜单项中的图标  复选框和单选按钮菜单项  弹出菜单  快捷键和加速器  启用和禁用菜单项  工具栏  工具提示

网格组布局 (GridBagLayout):GridBagLayout与GridLayout有点相似,它也是 将组件排在格子里,但是GridBagLayout在网格 的基础上提供更复杂的布局。

GridBagLayout允许单个组件在一个单元中不填 满整个单元,而只是占用最佳大小,也允许单个 组件扩展成不止一个单元,并且可以用任意顺序 加入组件。

定制布局管理器: 程序员可通过自己设计LayoutManager类来实现 特殊的布局方式。

定制布局管理器需要实现LayoutManager接口, 并覆盖以下方法。

 对话框

选项对话框   创建对话框   数据选择   文件对话框  颜色选择器

(1)对话框是一种大小不能变化、不能有菜单的容器窗口; 对话框不能作为一个应用程序的主框架,而必须包含在其 他的容器中。

(2)选项对话框:JOptionPane提供的对话框是模式对话框。当模 式对话框显示时,它不允许用户输入到程序的 其他的窗口。使用JOptionPane,可以创建和自 定义问题、信息、警告和错误等几种类型的对 话框。

(3)数据交换:输入对话框含有供用户输入文本的文本框、一个确认和取 消按钮,是有模式对话框。当输入对话框可见时,要求用户 输入一个字符串。

(4)文件对话框:专门用于对文件(或目录)进行浏览和选择的对 话框,常用的构造方法: – JFileChooser():根据用户的缺省目录创建文件对话框 – JFileChooser(File currentDirectory):根据File型参数 currentDirectory指定的目录创建文件对话框

(5)颜色对话框: javax.swing包中的JColorChooser类的静态方 法: public static Color showDialog(Component component, String title, Color initialColor)创建一个颜色对话框

(6)参数component指定对话框所依赖的组件,title 指定对话框的标题;initialColor 指定对话框返回 的初始颜色,即对话框消失后,返回的默认值。 颜色对话框可根据用户在颜色对话框中选择的颜 色返回一个颜色对象.

 

1、实验目的与要求

(1) 掌握GUI布局管理器用法;

(2) 掌握各类Java Swing组件用途及常用API;

2、实验内容和步骤

实验1: 导入第12章示例程序,测试程序并进行组内讨论。

测试程序1

l 在elipse IDE中运行教材479页程序12-1,结合运行结果理解程序;

l 掌握各种布局管理器的用法;

l 理解GUI界面中事件处理技术的用途。

l 在布局管理应用代码处添加注释;

package calculator;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

/**
 * A panel with calculator buttons and a result display.
 */
public class CalculatorPanel extends JPanel
{
   //属性
   private JButton display;
   private JPanel panel;
   private double result;
   private String lastCommand;
   private boolean start;
   //构造器
   public CalculatorPanel()
   {
      setLayout(new BorderLayout());//设定新的边框布局管理器

      result = 0;
      lastCommand = "=";
      start = true;

      // 添加display

      display = new JButton("0");//用来显示完成算式计算结果
      display.setEnabled(false);//使得使能属性不能起作用
      add(display, BorderLayout.NORTH);//将display添加到北部区域
      //生成监听器对象
      ActionListener insert = new InsertAction();
      ActionListener command = new CommandAction();

      // 在4 x 4网格中添加按钮

      panel = new JPanel();//新建窗格组件
      panel.setLayout(new GridLayout(4, 4));//设定4行4列的网格布局管理器
      //生成16个事件源,数字注册的事件源是insert对象,运算符注册的事件源是command对象
      addButton("7", insert);
      addButton("8", insert);
      addButton("9", insert);
      addButton("/", command);

      addButton("4", insert);
      addButton("5", insert);
      addButton("6", insert);
      addButton("*", command);

      addButton("1", insert);
      addButton("2", insert);
      addButton("3", insert);
      addButton("-", command);

      addButton("0", insert);
      addButton(".", insert);
      addButton("=", command);
      addButton("+", command);
       
      add(panel, BorderLayout.CENTER);//将panel添加到中部区域
     
   }

   /**
    * Adds a button to the center panel.
    * @param label the button label
    * @param listener the button listener
    */
   //方法
   private void addButton(String label, ActionListener listener)
   {
      JButton button = new JButton(label);//生成按钮对象
      button.addActionListener(listener);//注册监听器对象
      panel.add(button);//将其添加到窗格中
   }

   /**
    * This action inserts the button action string to the end of the display text.
    */
   //内部类
   private class InsertAction implements ActionListener
   {
      public void actionPerformed(ActionEvent event)
      {
         String input = event.getActionCommand();
         if (start)//开始计算
         {
            display.setText("");
            start = false;
         }
         display.setText(display.getText() + input);//完成多个数字的输入操作
      }
   }

   /**
    * This action executes the command that the button action string denotes.
    */
  //内部类
   private class CommandAction implements ActionListener
   {
      public void actionPerformed(ActionEvent event)
      {
         String command = event.getActionCommand();

         if (start)//开始计算还没有输入数字
         {
             
            if (command.equals("-"))
            {
               display.setText(command);//显示符号
               start = false;
            }
            else lastCommand = command;
         }
         else
         {
            calculate(Double.parseDouble(display.getText()));//将数字字符串转化为数字
            lastCommand = command;
            start = true;
         }
      }
   }

   /**
    * Carries out the pending calculation.
    * @param x the value to be accumulated with the prior result.
    */
   //计算方法
   public void calculate(double x)
   {
      if (lastCommand.equals("+")) result += x;
      else if (lastCommand.equals("-")) result -= x;
      else if (lastCommand.equals("*")) result *= x;
      else if (lastCommand.equals("/")) result /= x;
      else if (lastCommand.equals("=")) result = x;
      display.setText("" + result);//将数字转化为数字字符串输出
   }
}

  

package calculator;

import java.awt.*;
import javax.swing.*;

/**
 * @version 1.34 2015-06-12
 * @author Cay Horstmann
 */
public class Calculator
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         CalculatorFrame frame = new CalculatorFrame();
         frame.setTitle("Calculator");//设置标题
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//关闭
         frame.setVisible(true);//设置可见
      });
   }
}

 

package calculator;

import javax.swing.*;

/**
 * A frame with a calculator panel.
 */
public class CalculatorFrame extends JFrame
{
   public CalculatorFrame()
   {
      add(new CalculatorPanel());
      pack();
   }
}

  

 

 

测试程序2

l 在elipse IDE中调试运行教材486页程序12-2,结合运行结果理解程序;

l 掌握各种文本组件的用法;

l 记录示例代码阅读理解中存在的问题与疑惑。

package text;

import java.awt.BorderLayout;
import java.awt.GridLayout;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JPasswordField;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.SwingConstants;

/**
 * A frame with sample text components.
 */
public class TextComponentFrame extends JFrame
{
   public static final int TEXTAREA_ROWS = 8;
   public static final int TEXTAREA_COLUMNS = 20;

   public TextComponentFrame()
   {
      JTextField textField = new JTextField();
      JPasswordField passwordField = new JPasswordField();

      JPanel northPanel = new JPanel();
      northPanel.setLayout(new GridLayout(2, 2));
      northPanel.add(new JLabel("User name: ", SwingConstants.RIGHT));
      northPanel.add(textField);
      northPanel.add(new JLabel("Password: ", SwingConstants.RIGHT));
      northPanel.add(passwordField);

      add(northPanel, BorderLayout.NORTH);

      JTextArea textArea = new JTextArea(TEXTAREA_ROWS, TEXTAREA_COLUMNS);
      JScrollPane scrollPane = new JScrollPane(textArea);

      add(scrollPane, BorderLayout.CENTER);

      // add button to append text into the text area

      JPanel southPanel = new JPanel();

      JButton insertButton = new JButton("Insert");
      southPanel.add(insertButton);
      insertButton.addActionListener(event ->
         textArea.append("User name: " + textField.getText() + " Password: "
            + new String(passwordField.getPassword()) + "\n"));

      add(southPanel, BorderLayout.SOUTH);
      pack();
   }
}
package text;

import java.awt.*;
import javax.swing.*;

/**
 * @version 1.41 2015-06-12
 * @author Cay Horstmann
 */
public class TextComponentTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new TextComponentFrame();
         frame.setTitle("TextComponentTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

  

  

 

测试程序3

l 在elipse IDE中调试运行教材489页程序12-3,结合运行结果理解程序;

l 掌握复选框组件的用法;

l 记录示例代码阅读理解中存在的问题与疑惑。

package checkBox;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

/**
 * A frame with a sample text label and check boxes for selecting font
 * attributes.
 */
public class CheckBoxFrame extends JFrame
{
   private JLabel label;
   private JCheckBox bold;
   private JCheckBox italic;
   private static final int FONTSIZE = 24;

   public CheckBoxFrame()
   {
      // add the sample text label

      label = new JLabel("The quick brown fox jumps over the lazy dog.");
      label.setFont(new Font("Serif", Font.BOLD, FONTSIZE));
      add(label, BorderLayout.CENTER);

      // this listener sets the font attribute of
      // the label to the check box state

      ActionListener listener = event -> {
         int mode = 0;
         if (bold.isSelected()) mode += Font.BOLD;
         if (italic.isSelected()) mode += Font.ITALIC;
         label.setFont(new Font("Serif", mode, FONTSIZE));
      };

      // add the check boxes

      JPanel buttonPanel = new JPanel();

      bold = new JCheckBox("Bold");
      bold.addActionListener(listener);
      bold.setSelected(true);
      buttonPanel.add(bold);

      italic = new JCheckBox("Italic");
      italic.addActionListener(listener);
      buttonPanel.add(italic);

      add(buttonPanel, BorderLayout.SOUTH);
      pack();
   }
}

  

package checkBox;

import java.awt.*;
import javax.swing.*;

/**
 * @version 1.34 2015-06-12
 * @author Cay Horstmann
 */
public class CheckBoxTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new CheckBoxFrame();
         frame.setTitle("CheckBoxTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

  

 

 

测试程序4

l 在elipse IDE中调试运行教材491页程序12-4,运行结果理解程序;

l 掌握单选按钮组件的用法;

l 记录示例代码阅读理解中存在的问题与疑惑。

package radioButton;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

/**
 * A frame with a sample text label and radio buttons for selecting font sizes.
 */
public class RadioButtonFrame extends JFrame
{
   private JPanel buttonPanel;
   private ButtonGroup group;
   private JLabel label;
   private static final int DEFAULT_SIZE = 36;

   public RadioButtonFrame()
   {      
      // add the sample text label

      label = new JLabel("The quick brown fox jumps over the lazy dog.");
      label.setFont(new Font("Serif", Font.PLAIN, DEFAULT_SIZE));
      add(label, BorderLayout.CENTER);

      // add the radio buttons

      buttonPanel = new JPanel();
      group = new ButtonGroup();

      addRadioButton("Small", 8);
      addRadioButton("Medium", 12);
      addRadioButton("Large", 18);
      addRadioButton("Extra large", 36);

      add(buttonPanel, BorderLayout.SOUTH);
      pack();
   }

   /**
    * Adds a radio button that sets the font size of the sample text.
    * @param name the string to appear on the button
    * @param size the font size that this button sets
    */
   public void addRadioButton(String name, int size)
   {
      boolean selected = size == DEFAULT_SIZE;
      JRadioButton button = new JRadioButton(name, selected);
      group.add(button);
      buttonPanel.add(button);

      // this listener sets the label font size

      ActionListener listener = event -> label.setFont(new Font("Serif", Font.PLAIN, size));

      button.addActionListener(listener);
   }
}

  

package radioButton;

import java.awt.*;
import javax.swing.*;

/**
 * @version 1.34 2015-06-12
 * @author Cay Horstmann
 */
public class RadioButtonTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new RadioButtonFrame();
         frame.setTitle("RadioButtonTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

  

 

测试程序5

l 在elipse IDE中调试运行教材494页程序12-5,结合运行结果理解程序;

l 掌握边框的用法;

l 记录示例代码阅读理解中存在的问题与疑惑。

package border;

import java.awt.*;
import javax.swing.*;
import javax.swing.border.*;

/**
 * A frame with radio buttons to pick a border style.
 */
public class BorderFrame extends JFrame
{
   private JPanel demoPanel;
   private JPanel buttonPanel;
   private ButtonGroup group;

   public BorderFrame()
   {
      demoPanel = new JPanel();
      buttonPanel = new JPanel();
      group = new ButtonGroup();

      addRadioButton("Lowered bevel", BorderFactory.createLoweredBevelBorder());
      addRadioButton("Raised bevel", BorderFactory.createRaisedBevelBorder());
      addRadioButton("Etched", BorderFactory.createEtchedBorder());
      addRadioButton("Line", BorderFactory.createLineBorder(Color.BLUE));
      addRadioButton("Matte", BorderFactory.createMatteBorder(10, 10, 10, 10, Color.BLUE));
      addRadioButton("Empty", BorderFactory.createEmptyBorder());

      Border etched = BorderFactory.createEtchedBorder();
      Border titled = BorderFactory.createTitledBorder(etched, "Border types");
      buttonPanel.setBorder(titled);

      setLayout(new GridLayout(2, 1));
      add(buttonPanel);
      add(demoPanel);
      pack();
   }

   public void addRadioButton(String buttonName, Border b)
   {
      JRadioButton button = new JRadioButton(buttonName);
      button.addActionListener(event -> demoPanel.setBorder(b));
      group.add(button);
      buttonPanel.add(button);
   }
}

  

package border;

import java.awt.*;
import javax.swing.*;

/**
 * @version 1.34 2015-06-13
 * @author Cay Horstmann
 */
public class BorderTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new BorderFrame();
         frame.setTitle("BorderTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

  

 

 

 

测试程序6

l 在elipse IDE中调试运行教材498页程序12-6,结合运行结果理解程序;

l 掌握组合框组件的用法;

l 记录示例代码阅读理解中存在的问题与疑惑。

package comboBox;

import java.awt.BorderLayout;
import java.awt.Font;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

/**
 * A frame with a sample text label and a combo box for selecting font faces.
 */
public class ComboBoxFrame extends JFrame
{
   private JComboBox<String> faceCombo;
   private JLabel label;
   private static final int DEFAULT_SIZE = 24;

   public ComboBoxFrame()
   {
      // add the sample text label

      label = new JLabel("The quick brown fox jumps over the lazy dog.");
      label.setFont(new Font("Serif", Font.PLAIN, DEFAULT_SIZE));
      add(label, BorderLayout.CENTER);

      // make a combo box and add face names

      faceCombo = new JComboBox<>();
      faceCombo.addItem("Serif");
      faceCombo.addItem("SansSerif");
      faceCombo.addItem("Monospaced");
      faceCombo.addItem("Dialog");
      faceCombo.addItem("DialogInput");

      // the combo box listener changes the label font to the selected face name

      faceCombo.addActionListener(event ->
         label.setFont(
            new Font(faceCombo.getItemAt(faceCombo.getSelectedIndex()), 
               Font.PLAIN, DEFAULT_SIZE)));

      // add combo box to a panel at the frame's southern border

      JPanel comboPanel = new JPanel();
      comboPanel.add(faceCombo);
      add(comboPanel, BorderLayout.SOUTH);
      pack();
   }
}

  

package comboBox;

import java.awt.*;
import javax.swing.*;

/**
 * @version 1.35 2015-06-12
 * @author Cay Horstmann
 */
public class ComboBoxTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new ComboBoxFrame();
         frame.setTitle("ComboBoxTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

  

 

测试程序7

l 在elipse IDE中调试运行教材501页程序12-7,结合运行结果理解程序;

l 掌握滑动条组件的用法;

l 记录示例代码阅读理解中存在的问题与疑惑。

package slider;

import java.awt.*;
import java.util.*;
import javax.swing.*;
import javax.swing.event.*;

/**
 * A frame with many sliders and a text field to show slider values.
 */
public class SliderFrame extends JFrame
{
   private JPanel sliderPanel;
   private JTextField textField;
   private ChangeListener listener;

   public SliderFrame()
   {
      sliderPanel = new JPanel();
      sliderPanel.setLayout(new GridBagLayout());

      // common listener for all sliders
      listener = event -> {
         // update text field when the slider value changes
         JSlider source = (JSlider) event.getSource();
         textField.setText("" + source.getValue());
      };

      // add a plain slider

      JSlider slider = new JSlider();
      addSlider(slider, "Plain");

      // add a slider with major and minor ticks

      slider = new JSlider();
      slider.setPaintTicks(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(5);
      addSlider(slider, "Ticks");

      // add a slider that snaps to ticks

      slider = new JSlider();
      slider.setPaintTicks(true);
      slider.setSnapToTicks(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(5);
      addSlider(slider, "Snap to ticks");

      // add a slider with no track

      slider = new JSlider();
      slider.setPaintTicks(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(5);
      slider.setPaintTrack(false);
      addSlider(slider, "No track");

      // add an inverted slider

      slider = new JSlider();
      slider.setPaintTicks(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(5);
      slider.setInverted(true);
      addSlider(slider, "Inverted");

      // add a slider with numeric labels

      slider = new JSlider();
      slider.setPaintTicks(true);
      slider.setPaintLabels(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(5);
      addSlider(slider, "Labels");

      // add a slider with alphabetic labels

      slider = new JSlider();
      slider.setPaintLabels(true);
      slider.setPaintTicks(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(5);

      Dictionary<Integer, Component> labelTable = new Hashtable<>();
      labelTable.put(0, new JLabel("A"));
      labelTable.put(20, new JLabel("B"));
      labelTable.put(40, new JLabel("C"));
      labelTable.put(60, new JLabel("D"));
      labelTable.put(80, new JLabel("E"));
      labelTable.put(100, new JLabel("F"));

      slider.setLabelTable(labelTable);
      addSlider(slider, "Custom labels");

      // add a slider with icon labels

      slider = new JSlider();
      slider.setPaintTicks(true);
      slider.setPaintLabels(true);
      slider.setSnapToTicks(true);
      slider.setMajorTickSpacing(20);
      slider.setMinorTickSpacing(20);

      labelTable = new Hashtable<Integer, Component>();

      // add card images

      labelTable.put(0, new JLabel(new ImageIcon("nine.gif")));
      labelTable.put(20, new JLabel(new ImageIcon("ten.gif")));
      labelTable.put(40, new JLabel(new ImageIcon("jack.gif")));
      labelTable.put(60, new JLabel(new ImageIcon("queen.gif")));
      labelTable.put(80, new JLabel(new ImageIcon("king.gif")));
      labelTable.put(100, new JLabel(new ImageIcon("ace.gif")));

      slider.setLabelTable(labelTable);
      addSlider(slider, "Icon labels");

      // add the text field that displays the slider value

      textField = new JTextField();
      add(sliderPanel, BorderLayout.CENTER);
      add(textField, BorderLayout.SOUTH);
      pack();
   }

   /**
    * Adds a slider to the slider panel and hooks up the listener
    * @param s the slider
    * @param description the slider description
    */
   public void addSlider(JSlider s, String description)
   {
      s.addChangeListener(listener);
      JPanel panel = new JPanel();
      panel.add(s);
      panel.add(new JLabel(description));
      panel.setAlignmentX(Component.LEFT_ALIGNMENT);
      GridBagConstraints gbc = new GridBagConstraints();
      gbc.gridy = sliderPanel.getComponentCount();
      gbc.anchor = GridBagConstraints.WEST;
      sliderPanel.add(panel, gbc);
   }

  

package slider;

import java.awt.*;
import javax.swing.*;

/**
 * @version 1.15 2015-06-12
 * @author Cay Horstmann
 */
public class SliderTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         SliderFrame frame = new SliderFrame();
         frame.setTitle("SliderTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

  

 

测试程序8

l 在elipse IDE中调试运行教材512页程序12-8,结合运行结果理解程序;

l 掌握菜单的创建、菜单事件监听器、复选框和单选按钮菜单项、弹出菜单以及快捷键和加速器的用法。

l 记录示例代码阅读理解中存在的问题与疑惑。 

package menu;

import java.awt.event.*;
import javax.swing.*;

/**
 * A frame with a sample menu bar.
 */
public class MenuFrame extends JFrame
{
   private static final int DEFAULT_WIDTH = 300;
   private static final int DEFAULT_HEIGHT = 200;
   private Action saveAction;
   private Action saveAsAction;
   private JCheckBoxMenuItem readonlyItem;
   private JPopupMenu popup;

   /**
    * A sample action that prints the action name to System.out
    */
   class TestAction extends AbstractAction
   {
      public TestAction(String name)
      {
         super(name);
      }

      public void actionPerformed(ActionEvent event)
      {
         System.out.println(getValue(Action.NAME) + " selected.");
      }
   }

   public MenuFrame()
   {
      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

      JMenu fileMenu = new JMenu("File");
      fileMenu.add(new TestAction("New")); 
// 演示加速器 JMenuItem openItem = fileMenu.add(new TestAction("Open")); openItem.setAccelerator(KeyStroke.getKeyStroke("ctrl O")); fileMenu.addSeparator(); saveAction = new TestAction("Save"); JMenuItem saveItem = fileMenu.add(saveAction); saveItem.setAccelerator(KeyStroke.getKeyStroke("ctrl S")); saveAsAction = new TestAction("Save As"); fileMenu.add(saveAsAction); fileMenu.addSeparator(); fileMenu.add(new AbstractAction("Exit") { public void actionPerformed(ActionEvent event) { System.exit(0); } });
// 演示复选框和单选按钮菜单 readonlyItem = new JCheckBoxMenuItem("Read-only"); readonlyItem.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent event) { boolean saveOk = !readonlyItem.isSelected(); saveAction.setEnabled(saveOk); saveAsAction.setEnabled(saveOk); } }); ButtonGroup group = new ButtonGroup(); JRadioButtonMenuItem insertItem = new JRadioButtonMenuItem("Insert"); insertItem.setSelected(true); JRadioButtonMenuItem overtypeItem = new JRadioButtonMenuItem("Overtype"); group.add(insertItem); group.add(overtypeItem); // demonstrate icons Action cutAction = new TestAction("Cut"); cutAction.putValue(Action.SMALL_ICON, new ImageIcon("cut.gif")); Action copyAction = new TestAction("Copy"); copyAction.putValue(Action.SMALL_ICON, new ImageIcon("copy.gif")); Action pasteAction = new TestAction("Paste"); pasteAction.putValue(Action.SMALL_ICON, new ImageIcon("paste.gif")); JMenu editMenu = new JMenu("Edit"); editMenu.add(cutAction); editMenu.add(copyAction); editMenu.add(pasteAction); // 演示嵌套菜单 JMenu optionMenu = new JMenu("Options"); optionMenu.add(readonlyItem); optionMenu.addSeparator(); optionMenu.add(insertItem); optionMenu.add(overtypeItem); editMenu.addSeparator(); editMenu.add(optionMenu);    // 助记符演示 JMenu helpMenu = new JMenu("Help"); helpMenu.setMnemonic('H'); JMenuItem indexItem = new JMenuItem("Index"); indexItem.setMnemonic('I'); helpMenu.add(indexItem); // 还可以将助记键添加到动作中 Action aboutAction = new TestAction("About"); aboutAction.putValue(Action.MNEMONIC_KEY, new Integer('A')); helpMenu.add(aboutAction);  // 将所有顶级菜单添加到菜单栏 JMenuBar menuBar = new JMenuBar(); setJMenuBar(menuBar); menuBar.add(fileMenu); menuBar.add(editMenu); menuBar.add(helpMenu); // 演示弹出窗口 popup = new JPopupMenu(); popup.add(cutAction); popup.add(copyAction); popup.add(pasteAction); JPanel panel = new JPanel(); panel.setComponentPopupMenu(popup); add(panel); } }

  

package menu;

import java.awt.*;
import javax.swing.*;

/**
 * @version 1.24 2012-06-12
 * @author Cay Horstmann
 */
public class MenuTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new MenuFrame();
         frame.setTitle("MenuTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

  

 

  

测试程序9

l 在elipse IDE中调试运行教材517页程序12-9,结合运行结果理解程序;

l 掌握工具栏和工具提示的用法;

l 记录示例代码阅读理解中存在的问题与疑惑。

package toolBar;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

/**
 * A frame with a toolbar and menu for color changes.
 */
public class ToolBarFrame extends JFrame
{
   private static final int DEFAULT_WIDTH = 300;
   private static final int DEFAULT_HEIGHT = 200;
   private JPanel panel;

   public ToolBarFrame()
   {
      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

      // add a panel for color change

      panel = new JPanel();
      add(panel, BorderLayout.CENTER);

      // set up actions

      Action blueAction = new ColorAction("Blue", new ImageIcon("blue-ball.gif"), Color.BLUE);
      Action yellowAction = new ColorAction("Yellow", new ImageIcon("yellow-ball.gif"),
            Color.YELLOW);
      Action redAction = new ColorAction("Red", new ImageIcon("red-ball.gif"), Color.RED);

      Action exitAction = new AbstractAction("Exit", new ImageIcon("exit.gif"))
         {
            public void actionPerformed(ActionEvent event)
            {
               System.exit(0);
            }
         };
      exitAction.putValue(Action.SHORT_DESCRIPTION, "Exit");

      // populate toolbar

      JToolBar bar = new JToolBar();
      bar.add(blueAction);
      bar.add(yellowAction);
      bar.add(redAction);
      bar.addSeparator();
      bar.add(exitAction);
      add(bar, BorderLayout.NORTH);

      // populate menu

      JMenu menu = new JMenu("Color");
      menu.add(yellowAction);
      menu.add(blueAction);
      menu.add(redAction);
      menu.add(exitAction);
      JMenuBar menuBar = new JMenuBar();
      menuBar.add(menu);
      setJMenuBar(menuBar);
   }

   /**
    * The color action sets the background of the frame to a given color.
    */
   class ColorAction extends AbstractAction
   {
      public ColorAction(String name, Icon icon, Color c)
      {
         putValue(Action.NAME, name);
         putValue(Action.SMALL_ICON, icon);
         putValue(Action.SHORT_DESCRIPTION, name + " background");
         putValue("Color", c);
      }

      public void actionPerformed(ActionEvent event)
      {
         Color c = (Color) getValue("Color");
         panel.setBackground(c);
      }
   }
}

  

package toolBar;

import java.awt.*;
import javax.swing.*;

/**
 * @version 1.14 2015-06-12
 * @author Cay Horstmann
 */
public class ToolBarTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         ToolBarFrame frame = new ToolBarFrame();
         frame.setTitle("ToolBarTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

 

 

测试程序10

l 在elipse IDE中调试运行教材524页程序12-10、12-11,结合运行结果理解程序,了解GridbagLayout的用法。

package gridbag;

import java.awt.Font;
import java.awt.GridBagLayout;
import java.awt.event.ActionListener;

import javax.swing.BorderFactory;
import javax.swing.JCheckBox;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextArea;

/**
 * A frame that uses a grid bag layout to arrange font selection components.
 */
public class FontFrame extends JFrame
{
   public static final int TEXT_ROWS = 10;
   public static final int TEXT_COLUMNS = 20;

   private JComboBox<String> face;
   private JComboBox<Integer> size;
   private JCheckBox bold;
   private JCheckBox italic;
   private JTextArea sample;

   public FontFrame()
   {
      GridBagLayout layout = new GridBagLayout();
      setLayout(layout);

      ActionListener listener = event -> updateSample();

      // construct components

      JLabel faceLabel = new JLabel("Face: ");

      face = new JComboBox<>(new String[] { "Serif", "SansSerif", "Monospaced",
            "Dialog", "DialogInput" });

      face.addActionListener(listener);

      JLabel sizeLabel = new JLabel("Size: ");

      size = new JComboBox<>(new Integer[] { 8, 10, 12, 15, 18, 24, 36, 48 });

      size.addActionListener(listener);

      bold = new JCheckBox("Bold");
      bold.addActionListener(listener);

      italic = new JCheckBox("Italic");
      italic.addActionListener(listener);

      sample = new JTextArea(TEXT_ROWS, TEXT_COLUMNS);
      sample.setText("The quick brown fox jumps over the lazy dog");
      sample.setEditable(false);
      sample.setLineWrap(true);
      sample.setBorder(BorderFactory.createEtchedBorder());

      // add components to grid, using GBC convenience class

      add(faceLabel, new GBC(0, 0).setAnchor(GBC.EAST));
      add(face, new GBC(1, 0).setFill(GBC.HORIZONTAL).setWeight(100, 0)
            .setInsets(1));
      add(sizeLabel, new GBC(0, 1).setAnchor(GBC.EAST));
      add(size, new GBC(1, 1).setFill(GBC.HORIZONTAL).setWeight(100, 0)
            .setInsets(1));
      add(bold, new GBC(0, 2, 2, 1).setAnchor(GBC.CENTER).setWeight(100, 100));
      add(italic, new GBC(0, 3, 2, 1).setAnchor(GBC.CENTER).setWeight(100, 100));
      add(sample, new GBC(2, 0, 1, 4).setFill(GBC.BOTH).setWeight(100, 100));
      pack();
      updateSample();
   }

   public void updateSample()
   {
      String fontFace = (String) face.getSelectedItem();
      int fontStyle = (bold.isSelected() ? Font.BOLD : 0)
            + (italic.isSelected() ? Font.ITALIC : 0);
      int fontSize = size.getItemAt(size.getSelectedIndex());
      Font font = new Font(fontFace, fontStyle, fontSize);
      sample.setFont(font);
      sample.repaint();
   }
}

  

package gridbag;

import java.awt.*;

/**
 * This class simplifies the use of the GridBagConstraints class.
 * @version 1.01 2004-05-06
 * @author Cay Horstmann
 */
public class GBC extends GridBagConstraints
{
   /**
    * Constructs a GBC with a given gridx and gridy position and all other grid
    * bag constraint values set to the default.
    * @param gridx the gridx position
    * @param gridy the gridy position
    */
   public GBC(int gridx, int gridy)
   {
      this.gridx = gridx;
      this.gridy = gridy;
   }

   /**
    * Constructs a GBC with given gridx, gridy, gridwidth, gridheight and all
    * other grid bag constraint values set to the default.
    * @param gridx the gridx position
    * @param gridy the gridy position
    * @param gridwidth the cell span in x-direction
    * @param gridheight the cell span in y-direction
    */
   public GBC(int gridx, int gridy, int gridwidth, int gridheight)
   {
      this.gridx = gridx;
      this.gridy = gridy;
      this.gridwidth = gridwidth;
      this.gridheight = gridheight;
   }

   /**
    * Sets the anchor.
    * @param anchor the anchor value
    * @return this object for further modification
    */
   public GBC setAnchor(int anchor)
   {
      this.anchor = anchor;
      return this;
   }

   /**
    * Sets the fill direction.
    * @param fill the fill direction
    * @return this object for further modification
    */
   public GBC setFill(int fill)
   {
      this.fill = fill;
      return this;
   }

   /**
    * Sets the cell weights.
    * @param weightx the cell weight in x-direction
    * @param weighty the cell weight in y-direction
    * @return this object for further modification
    */
   public GBC setWeight(double weightx, double weighty)
   {
      this.weightx = weightx;
      this.weighty = weighty;
      return this;
   }

   /**
    * Sets the insets of this cell.
    * @param distance the spacing to use in all directions
    * @return this object for further modification
    */
   public GBC setInsets(int distance)
   {
      this.insets = new Insets(distance, distance, distance, distance);
      return this;
   }

   /**
    * Sets the insets of this cell.
    * @param top the spacing to use on top
    * @param left the spacing to use to the left
    * @param bottom the spacing to use on the bottom
    * @param right the spacing to use to the right
    * @return this object for further modification
    */
   public GBC setInsets(int top, int left, int bottom, int right)
   {
      this.insets = new Insets(top, left, bottom, right);
      return this;
   }

   /**
    * Sets the internal padding
    * @param ipadx the internal padding in x-direction
    * @param ipady the internal padding in y-direction
    * @return this object for further modification
    */
   public GBC setIpad(int ipadx, int ipady)
   {
      this.ipadx = ipadx;
      this.ipady = ipady;
      return this;
   }
}

 

package gridbag;

import java.awt.EventQueue;

import javax.swing.JFrame;

/**
 * @version 1.35 2015-06-12
 * @author Cay Horstmann
 */
public class GridBagLayoutTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() ->           {
               JFrame frame = new FontFrame();
               frame.setTitle("GridBagLayoutTest");
               frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               frame.setVisible(true);
         });
   }
}

  

 

 

l 在elipse IDE中调试运行教材533页程序12-12,结合程序运行结果理解程序,了解GroupLayout的用法。

l 记录示例代码阅读理解中存在的问题与疑惑。

1 package groupLayout;
 2 
 3 import java.awt.EventQueue;
 4 
 5 import javax.swing.JFrame;
 6 
 7 /**
 8  * @version 1.01 2015-06-12
 9  * @author Cay Horstmann
10  */
11 public class GroupLayoutTest
12 {
13    public static void main(String[] args)
14    {
15       EventQueue.invokeLater(() -> {
16          JFrame frame = new FontFrame();
17          frame.setTitle("GroupLayoutTest");
18          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
19          frame.setVisible(true);
20       });
21    }
22 }

  

1 package groupLayout;
  2 
  3 import java.awt.Font;
  4 import java.awt.event.ActionListener;
  5 
  6 import javax.swing.BorderFactory;
  7 import javax.swing.GroupLayout;
  8 import javax.swing.JCheckBox;
  9 import javax.swing.JComboBox;
 10 import javax.swing.JFrame;
 11 import javax.swing.JLabel;
 12 import javax.swing.JScrollPane;
 13 import javax.swing.JTextArea;
 14 import javax.swing.LayoutStyle;
 15 import javax.swing.SwingConstants;
 16 
 17 /**
 18  * A frame that uses a group layout to arrange font selection components.
 19  */
 20 public class FontFrame extends JFrame
 21 {
 22    public static final int TEXT_ROWS = 10;
 23    public static final int TEXT_COLUMNS = 20;
 24 
 25    private JComboBox<String> face;
 26    private JComboBox<Integer> size;
 27    private JCheckBox bold;
 28    private JCheckBox italic;
 29    private JScrollPane pane;
 30    private JTextArea sample;
 31 
 32    public FontFrame()
 33    {
 34       ActionListener listener = event -> updateSample(); 
 35 
 36       // construct components
 37 
 38       JLabel faceLabel = new JLabel("Face: ");
 39 
 40       face = new JComboBox<>(new String[] { "Serif", "SansSerif", "Monospaced", "Dialog",
 41             "DialogInput" });
 42 
 43       face.addActionListener(listener);
 44 
 45       JLabel sizeLabel = new JLabel("Size: ");
 46 
 47       size = new JComboBox<>(new Integer[] { 8, 10, 12, 15, 18, 24, 36, 48 });
 48 
 49       size.addActionListener(listener);
 50 
 51       bold = new JCheckBox("Bold");
 52       bold.addActionListener(listener);
 53 
 54       italic = new JCheckBox("Italic");
 55       italic.addActionListener(listener);
 56 
 57       sample = new JTextArea(TEXT_ROWS, TEXT_COLUMNS);
 58       sample.setText("The quick brown fox jumps over the lazy dog");
 59       sample.setEditable(false);
 60       sample.setLineWrap(true);
 61       sample.setBorder(BorderFactory.createEtchedBorder());
 62 
 63       pane = new JScrollPane(sample);
 64 
 65       GroupLayout layout = new GroupLayout(getContentPane());
 66       setLayout(layout);
 67       layout.setHorizontalGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
 68             .addGroup(
 69                   layout.createSequentialGroup().addContainerGap().addGroup(
 70                         layout.createParallelGroup(GroupLayout.Alignment.LEADING).addGroup(
 71                               GroupLayout.Alignment.TRAILING,
 72                               layout.createSequentialGroup().addGroup(
 73                                     layout.createParallelGroup(GroupLayout.Alignment.TRAILING)
 74                                           .addComponent(faceLabel).addComponent(sizeLabel))
 75                                     .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
 76                                     .addGroup(
 77                                           layout.createParallelGroup(
 78                                                 GroupLayout.Alignment.LEADING, false)
 79                                                 .addComponent(size).addComponent(face)))
 80                               .addComponent(italic).addComponent(bold)).addPreferredGap(
 81                         LayoutStyle.ComponentPlacement.RELATED).addComponent(pane)
 82                         .addContainerGap()));
 83 
 84       layout.linkSize(SwingConstants.HORIZONTAL, new java.awt.Component[] { face, size });
 85 
 86       layout.setVerticalGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
 87             .addGroup(
 88                   layout.createSequentialGroup().addContainerGap().addGroup(
 89                         layout.createParallelGroup(GroupLayout.Alignment.LEADING).addComponent(
 90                               pane, GroupLayout.Alignment.TRAILING).addGroup(
 91                               layout.createSequentialGroup().addGroup(
 92                                     layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
 93                                           .addComponent(face).addComponent(faceLabel))
 94                                     .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
 95                                     .addGroup(
 96                                           layout.createParallelGroup(
 97                                                 GroupLayout.Alignment.BASELINE).addComponent(size)
 98                                                 .addComponent(sizeLabel)).addPreferredGap(
 99                                           LayoutStyle.ComponentPlacement.RELATED).addComponent(
100                                           italic, GroupLayout.DEFAULT_SIZE,
101                                           GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
102                                     .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
103                                     .addComponent(bold, GroupLayout.DEFAULT_SIZE,
104                                           GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
105                         .addContainerGap()));
106       pack();
107    }
108    
109    public void updateSample()
110    {
111       String fontFace = (String) face.getSelectedItem();
112       int fontStyle = (bold.isSelected() ? Font.BOLD : 0)
113             + (italic.isSelected() ? Font.ITALIC : 0);
114       int fontSize = size.getItemAt(size.getSelectedIndex());
115       Font font = new Font(fontFace, fontStyle, fontSize);
116       sample.setFont(font);
117       sample.repaint();
118    }
119 }

  

 

 

 

 

测试程序11

l 在elipse IDE中调试运行教材539页程序12-13、12-14,结合运行结果理解程序;

l 掌握定制布局管理器的用法。

l 记录示例代码阅读理解中存在的问题与疑惑。 

 package circleLayout;
 2 
 3 import java.awt.*;
 4 import javax.swing.*;
 5 
 6 /**
 7  * @version 1.33 2015-06-12
 8  * @author Cay Horstmann
 9  */
10 public class CircleLayoutTest
11 {
12    public static void main(String[] args)
13    {
14       EventQueue.invokeLater(() -> {
15          JFrame frame = new CircleLayoutFrame();
16          frame.setTitle("CircleLayoutTest");
17          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
18          frame.setVisible(true);
19       });
20    }
21 }

  

 1 package circleLayout;
 2 
 3 import javax.swing.*;
 4 
 5 /**
 6  * A frame that shows buttons arranged along a circle.
 7  */
 8 public class CircleLayoutFrame extends JFrame
 9 {
10    public CircleLayoutFrame()
11    {
12       setLayout(new CircleLayout());
13       add(new JButton("Yellow"));
14       add(new JButton("Blue"));
15       add(new JButton("Red"));
16       add(new JButton("Green"));
17       add(new JButton("Orange"));
18       add(new JButton("Fuchsia"));
19       add(new JButton("Indigo"));
20       pack();
21    }
22 }

  

1 package circleLayout;
  2 
  3 import java.awt.*;
  4 
  5 /**
  6  * A layout manager that lays out components along a circle.
  7  */
  8 public class CircleLayout implements LayoutManager
  9 {
 10    private int minWidth = 0;
 11    private int minHeight = 0;
 12    private int preferredWidth = 0;
 13    private int preferredHeight = 0;
 14    private boolean sizesSet = false;
 15    private int maxComponentWidth = 0;
 16    private int maxComponentHeight = 0;
 17 
 18    public void addLayoutComponent(String name, Component comp)
 19    {
 20    }
 21 
 22    public void removeLayoutComponent(Component comp)
 23    {
 24    }
 25 
 26    public void setSizes(Container parent)
 27    {
 28       if (sizesSet) return;
 29       int n = parent.getComponentCount();
 30 
 31       preferredWidth = 0;
 32       preferredHeight = 0;
 33       minWidth = 0;
 34       minHeight = 0;
 35       maxComponentWidth = 0;
 36       maxComponentHeight = 0;
 37 
 38       // compute the maximum component widths and heights
 39       // and set the preferred size to the sum of the component sizes.
 40       for (int i = 0; i < n; i++)
 41       {
 42          Component c = parent.getComponent(i);
 43          if (c.isVisible())
 44          {
 45             Dimension d = c.getPreferredSize();
 46             maxComponentWidth = Math.max(maxComponentWidth, d.width);
 47             maxComponentHeight = Math.max(maxComponentHeight, d.height);
 48             preferredWidth += d.width;
 49             preferredHeight += d.height;
 50          }
 51       }
 52       minWidth = preferredWidth / 2;
 53       minHeight = preferredHeight / 2;
 54       sizesSet = true;
 55    }
 56 
 57    public Dimension preferredLayoutSize(Container parent)
 58    {
 59       setSizes(parent);
 60       Insets insets = parent.getInsets();
 61       int width = preferredWidth + insets.left + insets.right;
 62       int height = preferredHeight + insets.top + insets.bottom;
 63       return new Dimension(width, height);
 64    }
 65 
 66    public Dimension minimumLayoutSize(Container parent)
 67    {
 68       setSizes(parent);
 69       Insets insets = parent.getInsets();
 70       int width = minWidth + insets.left + insets.right;
 71       int height = minHeight + insets.top + insets.bottom;
 72       return new Dimension(width, height);
 73    }
 74 
 75    public void layoutContainer(Container parent)
 76    {
 77       setSizes(parent);
 78 
 79       // compute center of the circle
 80 
 81       Insets insets = parent.getInsets();
 82       int containerWidth = parent.getSize().width - insets.left - insets.right;
 83       int containerHeight = parent.getSize().height - insets.top - insets.bottom;
 84 
 85       int xcenter = insets.left + containerWidth / 2;
 86       int ycenter = insets.top + containerHeight / 2;
 87 
 88       // compute radius of the circle
 89 
 90       int xradius = (containerWidth - maxComponentWidth) / 2;
 91       int yradius = (containerHeight - maxComponentHeight) / 2;
 92       int radius = Math.min(xradius, yradius);
 93 
 94       // lay out components along the circle
 95 
 96       int n = parent.getComponentCount();
 97       for (int i = 0; i < n; i++)
 98       {
 99          Component c = parent.getComponent(i);
100          if (c.isVisible())
101          {
102             double angle = 2 * Math.PI * i / n;
103 
104             // center point of component
105             int x = xcenter + (int) (Math.cos(angle) * radius);
106             int y = ycenter + (int) (Math.sin(angle) * radius);
107 
108             // move component so that its center is (x, y)
109             // and its size is its preferred size
110             Dimension d = c.getPreferredSize();
111             c.setBounds(x - d.width / 2, y - d.height / 2, d.width, d.height);
112          }
113       }
114    }
115 }

   

  

 

  

 

测试程序12

l 在elipse IDE中调试运行教材544页程序12-15、12-16,结合运行结果理解程序;

l 掌握选项对话框的用法。

l 记录示例代码阅读理解中存在的问题与疑惑。

1 package optionDialog;
 2 
 3 import java.awt.*;
 4 import javax.swing.*;
 5 
 6 /**
 7  * @version 1.34 2015-06-12
 8  * @author Cay Horstmann
 9  */
10 public class OptionDialogTest
11 {
12    public static void main(String[] args)
13    {
14       EventQueue.invokeLater(() -> {
15          JFrame frame = new OptionDialogFrame();
16          frame.setTitle("OptionDialogTest");
17          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
18          frame.setVisible(true);
19       });
20    }
21 }

  

1 package optionDialog;
 2 
 3 import javax.swing.*;
 4 
 5 /**
 6  * A panel with radio buttons inside a titled border.
 7  */
 8 public class ButtonPanel extends JPanel
 9 {
10    private ButtonGroup group;
11 
12    /**
13     * Constructs a button panel.
14     * @param title the title shown in the border
15     * @param options an array of radio button labels
16     */
17    public ButtonPanel(String title, String... options)
18    {
19       setBorder(BorderFactory.createTitledBorder(BorderFactory.createEtchedBorder(), title));
20       setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
21       group = new ButtonGroup();
22 
23       // make one radio button for each option
24       for (String option : options)
25       {
26          JRadioButton b = new JRadioButton(option);
27          b.setActionCommand(option);
28          add(b);
29          group.add(b);
30          b.setSelected(option == options[0]);
31       }
32    }
33 
34    /**
35     * Gets the currently selected option.
36     * @return the label of the currently selected radio button.
37     */
38    public String getSelection()
39    {
40       return group.getSelection().getActionCommand();
41    }
42 }

  

1 package optionDialog;
  2 
  3 import java.awt.*;
  4 import java.awt.event.*;
  5 import java.awt.geom.*;
  6 import java.util.*;
  7 import javax.swing.*;
  8 
  9 /**
 10  * A frame that contains settings for selecting various option dialogs.
 11  */
 12 public class OptionDialogFrame extends JFrame
 13 {
 14    private ButtonPanel typePanel;
 15    private ButtonPanel messagePanel;
 16    private ButtonPanel messageTypePanel;
 17    private ButtonPanel optionTypePanel;
 18    private ButtonPanel optionsPanel;
 19    private ButtonPanel inputPanel;
 20    private String messageString = "Message";
 21    private Icon messageIcon = new ImageIcon("blue-ball.gif");
 22    private Object messageObject = new Date();
 23    private Component messageComponent = new SampleComponent();
 24 
 25    public OptionDialogFrame()
 26    {
 27       JPanel gridPanel = new JPanel();
 28       gridPanel.setLayout(new GridLayout(2, 3));
 29 
 30       typePanel = new ButtonPanel("Type", "Message", "Confirm", "Option", "Input");
 31       messageTypePanel = new ButtonPanel("Message Type", "ERROR_MESSAGE", "INFORMATION_MESSAGE",
 32             "WARNING_MESSAGE", "QUESTION_MESSAGE", "PLAIN_MESSAGE");
 33       messagePanel = new ButtonPanel("Message", "String", "Icon", "Component", "Other", 
 34             "Object[]");
 35       optionTypePanel = new ButtonPanel("Confirm", "DEFAULT_OPTION", "YES_NO_OPTION",
 36             "YES_NO_CANCEL_OPTION", "OK_CANCEL_OPTION");
 37       optionsPanel = new ButtonPanel("Option", "String[]", "Icon[]", "Object[]");
 38       inputPanel = new ButtonPanel("Input", "Text field", "Combo box");
 39 
 40       gridPanel.add(typePanel);
 41       gridPanel.add(messageTypePanel);
 42       gridPanel.add(messagePanel);
 43       gridPanel.add(optionTypePanel);
 44       gridPanel.add(optionsPanel);
 45       gridPanel.add(inputPanel);
 46 
 47       // add a panel with a Show button
 48 
 49       JPanel showPanel = new JPanel();
 50       JButton showButton = new JButton("Show");
 51       showButton.addActionListener(new ShowAction());
 52       showPanel.add(showButton);
 53 
 54       add(gridPanel, BorderLayout.CENTER);
 55       add(showPanel, BorderLayout.SOUTH);
 56       pack();
 57    }
 58 
 59    /**
 60     * Gets the currently selected message.
 61     * @return a string, icon, component, or object array, depending on the Message panel selection
 62     */
 63    public Object getMessage()
 64    {
 65       String s = messagePanel.getSelection();
 66       if (s.equals("String")) return messageString;
 67       else if (s.equals("Icon")) return messageIcon;
 68       else if (s.equals("Component")) return messageComponent;
 69       else if (s.equals("Object[]")) return new Object[] { messageString, messageIcon,
 70             messageComponent, messageObject };
 71       else if (s.equals("Other")) return messageObject;
 72       else return null;
 73    }
 74 
 75    /**
 76     * Gets the currently selected options.
 77     * @return an array of strings, icons, or objects, depending on the Option panel selection
 78     */
 79    public Object[] getOptions()
 80    {
 81       String s = optionsPanel.getSelection();
 82       if (s.equals("String[]")) return new String[] { "Yellow", "Blue", "Red" };
 83       else if (s.equals("Icon[]")) return new Icon[] { new ImageIcon("yellow-ball.gif"),
 84             new ImageIcon("blue-ball.gif"), new ImageIcon("red-ball.gif") };
 85       else if (s.equals("Object[]")) return new Object[] { messageString, messageIcon,
 86             messageComponent, messageObject };
 87       else return null;
 88    }
 89 
 90    /**
 91     * Gets the selected message or option type
 92     * @param panel the Message Type or Confirm panel
 93     * @return the selected XXX_MESSAGE or XXX_OPTION constant from the JOptionPane class
 94     */
 95    public int getType(ButtonPanel panel)
 96    {
 97       String s = panel.getSelection();
 98       try
 99       {
100          return JOptionPane.class.getField(s).getInt(null);
101       }
102       catch (Exception e)
103       {
104          return -1;
105       }
106    }
107 
108    /**
109     * The action listener for the Show button shows a Confirm, Input, Message, or Option dialog
110     * depending on the Type panel selection.
111     */
112    private class ShowAction implements ActionListener
113    {
114       public void actionPerformed(ActionEvent event)
115       {
116          if (typePanel.getSelection().equals("Confirm")) JOptionPane.showConfirmDialog(
117                OptionDialogFrame.this, getMessage(), "Title", getType(optionTypePanel),
118                getType(messageTypePanel));
119          else if (typePanel.getSelection().equals("Input"))
120          {
121             if (inputPanel.getSelection().equals("Text field")) JOptionPane.showInputDialog(
122                   OptionDialogFrame.this, getMessage(), "Title", getType(messageTypePanel));
123             else JOptionPane.showInputDialog(OptionDialogFrame.this, getMessage(), "Title",
124                   getType(messageTypePanel), null, new String[] { "Yellow", "Blue", "Red" },
125                   "Blue");
126          }
127          else if (typePanel.getSelection().equals("Message")) JOptionPane.showMessageDialog(
128                OptionDialogFrame.this, getMessage(), "Title", getType(messageTypePanel));
129          else if (typePanel.getSelection().equals("Option")) JOptionPane.showOptionDialog(
130                OptionDialogFrame.this, getMessage(), "Title", getType(optionTypePanel),
131                getType(messageTypePanel), null, getOptions(), getOptions()[0]);
132       }
133    }
134 }
135 
136 /**
137  * A component with a painted surface
138  */
139 
140 class SampleComponent extends JComponent
141 {
142    public void paintComponent(Graphics g)
143    {
144       Graphics2D g2 = (Graphics2D) g;
145       Rectangle2D rect = new Rectangle2D.Double(0, 0, getWidth() - 1, getHeight() - 1);
146       g2.setPaint(Color.YELLOW);
147       g2.fill(rect);
148       g2.setPaint(Color.BLUE);
149       g2.draw(rect);
150    }
151 
152    public Dimension getPreferredSize()
153    {
154       return new Dimension(10, 10);
155    }
156 }

  

 

 

 

测试程序13

l 在elipse IDE中调试运行教材552页程序12-17、12-18,结合运行结果理解程序;

l 掌握对话框的创建方法;

l 记录示例代码阅读理解中存在的问题与疑惑。

package dialog;

import java.awt.*;
import javax.swing.*;

/**
 * @version 1.34 2012-06-12
 * @author Cay Horstmann
 */
public class DialogTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(() -> {
         JFrame frame = new DialogFrame();
         frame.setTitle("DialogTest");
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setVisible(true);
      });
   }
}

  

 package dialog;

import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;

/**
 * A frame with a menu whose File->About action shows a dialog.
 */
public class DialogFrame extends JFrame
{
   private static final int DEFAULT_WIDTH = 300;
   private static final int DEFAULT_HEIGHT = 200;
   private AboutDialog dialog;

   public DialogFrame()
   {
      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

      // Construct a File menu.

      JMenuBar menuBar = new JMenuBar();//菜单栏的实现
      setJMenuBar(menuBar);//设置此窗体的菜单栏
      JMenu fileMenu = new JMenu("File");//菜单的该实现是一个包含 JMenuItem 的弹出窗口,用户选择 JMenuBar 上的项时会显示该 JMenuItem。
      menuBar.add(fileMenu);//将指定的菜单追加到菜单栏的末尾

      // Add About and Exit menu items.

      // The About item shows the About dialog.

      JMenuItem aboutItem = new JMenuItem("About");//菜单中的项的实现
      aboutItem.addActionListener(event -> {
         if (dialog == null) // first time
            dialog = new AboutDialog(DialogFrame.this);
         dialog.setVisible(true); // 设置是否可见
      });
      fileMenu.add(aboutItem);//将某个菜单项追加到此菜单的末尾。返回添加的菜单项

      // The Exit item exits the program.

      JMenuItem exitItem = new JMenuItem("Exit");
      exitItem.addActionListener(event -> System.exit(0));
      fileMenu.add(exitItem);
   }
} 

  

1 package dialog;
 2 
 3 import java.awt.BorderLayout;
 4 
 5 import javax.swing.JButton;
 6 import javax.swing.JDialog;
 7 import javax.swing.JFrame;
 8 import javax.swing.JLabel;
 9 import javax.swing.JPanel;
10 
11 /**
12  * A sample modal dialog that displays a message and waits for the user to click the OK button.
13  */
14 public class AboutDialog extends JDialog
15 {//创建一个具有指定标题,所有者Farmer和模式的对话框。如果owner为null,则一个共享的,隐藏的窗体将设置为该对话框的所有者。
16    public AboutDialog(JFrame owner)
17    {
18       super(owner, "About DialogTest", true);
19 
20       // add HTML label to center//将指定的组件添加到此内容的尾部
21 
22       add(
23             new JLabel(
24                   "<html><h1><i>Core Java</i></h1><hr>By Cay Horstmann</html>"),
25             BorderLayout.CENTER);
26 
27       // OK button closes the dialog
28 
29       JButton ok = new JButton("OK");//创建一个新的按钮
30       ok.addActionListener(event -> setVisible(false));
31 
32       // add OK button to southern border
33 
34       JPanel panel = new JPanel();
35       panel.add(ok);
36       add(panel, BorderLayout.SOUTH);//边框布局,显示在下边
37 
38       pack();
39    }
40 }

  

 

 

测试程序14

l 在elipse IDE中调试运行教材556页程序12-19、12-20,结合运行结果理解程序;

l 掌握对话框的数据交换用法;

l 记录示例代码阅读理解中存在的问题与疑惑。

1 package dataExchange;
 2 
 3 import java.awt.*;
 4 import javax.swing.*;
 5 
 6 /**
 7  * @version 1.34 2015-06-12
 8  * @author Cay Horstmann
 9  */
10 public class DataExchangeTest
11 {
12    public static void main(String[] args)
13    {
14       EventQueue.invokeLater(() -> {
15          JFrame frame = new DataExchangeFrame();
16          frame.setTitle("DataExchangeTest");
17          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
18          frame.setVisible(true);
19       });
20    }
21 }

  

1 package dataExchange;
 2 
 3 import java.awt.*;
 4 import java.awt.event.*;
 5 import javax.swing.*;
 6 
 7 /**
 8  * A frame with a menu whose File->Connect action shows a password dialog.
 9  */
10 public class DataExchangeFrame extends JFrame
11 {
12    public static final int TEXT_ROWS = 20;
13    public static final int TEXT_COLUMNS = 40;
14    private PasswordChooser dialog = null;
15    private JTextArea textArea;
16 
17    public DataExchangeFrame()
18    {
19       // construct a File menu
20 
21       JMenuBar mbar = new JMenuBar();
22       setJMenuBar(mbar);
23       JMenu fileMenu = new JMenu("File");
24       mbar.add(fileMenu);
25 
26       // add Connect and Exit menu items
27 
28       JMenuItem connectItem = new JMenuItem("Connect");
29       connectItem.addActionListener(new ConnectAction());
30       fileMenu.add(connectItem);
31 
32       // The Exit item exits the program
33 
34       JMenuItem exitItem = new JMenuItem("Exit");
35       exitItem.addActionListener(event -> System.exit(0));
36       fileMenu.add(exitItem);
37 
38       textArea = new JTextArea(TEXT_ROWS, TEXT_COLUMNS);
39       add(new JScrollPane(textArea), BorderLayout.CENTER);
40       pack();
41    }
42 
43    /**
44     * The Connect action pops up the password dialog.
45     */
46    private class ConnectAction implements ActionListener
47    {
48       public void actionPerformed(ActionEvent event)
49       {
50          // if first time, construct dialog
51 
52          if (dialog == null) dialog = new PasswordChooser();
53 
54          // set default values
55          dialog.setUser(new User("yourname", null));
56 
57          // pop up dialog
58          if (dialog.showDialog(DataExchangeFrame.this, "Connect"))
59          {
60             // if accepted, retrieve user input
61             User u = dialog.getUser();
62             textArea.append("user name = " + u.getName() + ", password = "
63                   + (new String(u.getPassword())) + "\n");
64          }
65       }
66    }
67 }

  

1 package dataExchange;
  2 
  3 import java.awt.BorderLayout;
  4 import java.awt.Component;
  5 import java.awt.Frame;
  6 import java.awt.GridLayout;
  7 
  8 import javax.swing.JButton;
  9 import javax.swing.JDialog;
 10 import javax.swing.JLabel;
 11 import javax.swing.JPanel;
 12 import javax.swing.JPasswordField;
 13 import javax.swing.JTextField;
 14 import javax.swing.SwingUtilities;
 15 
 16 /**
 17  * A password chooser that is shown inside a dialog
 18  */
 19 public class PasswordChooser extends JPanel
 20 {
 21    private JTextField username;
 22    private JPasswordField password;
 23    private JButton okButton;
 24    private boolean ok;
 25    private JDialog dialog;
 26 
 27    public PasswordChooser()
 28    {
 29       setLayout(new BorderLayout());
 30 
 31       // construct a panel with user name and password fields
 32 
 33       JPanel panel = new JPanel();
 34       panel.setLayout(new GridLayout(2, 2));
 35       panel.add(new JLabel("User name:"));
 36       panel.add(username = new JTextField(""));
 37       panel.add(new JLabel("Password:"));
 38       panel.add(password = new JPasswordField(""));
 39       add(panel, BorderLayout.CENTER);
 40 
 41       // create Ok and Cancel buttons that terminate the dialog
 42 
 43       okButton = new JButton("Ok");
 44       okButton.addActionListener(event -> {
 45          ok = true;
 46          dialog.setVisible(false);
 47       });
 48 
 49       JButton cancelButton = new JButton("Cancel");
 50       cancelButton.addActionListener(event -> dialog.setVisible(false));
 51 
 52       // add buttons to southern border
 53 
 54       JPanel buttonPanel = new JPanel();
 55       buttonPanel.add(okButton);
 56       buttonPanel.add(cancelButton);
 57       add(buttonPanel, BorderLayout.SOUTH);
 58    }
 59 
 60    /**
 61     * Sets the dialog defaults.
 62     * @param u the default user information
 63     */
 64    public void setUser(User u)
 65    {
 66       username.setText(u.getName());
 67    }
 68 
 69    /**
 70     * Gets the dialog entries.
 71     * @return a User object whose state represents the dialog entries
 72     */
 73    public User getUser()
 74    {
 75       return new User(username.getText(), password.getPassword());
 76    }
 77 
 78    /**
 79     * Show the chooser panel in a dialog
 80     * @param parent a component in the owner frame or null
 81     * @param title the dialog window title
 82     */
 83    public boolean showDialog(Component parent, String title)
 84    {
 85       ok = false;
 86 
 87       // locate the owner frame
 88 
 89       Frame owner = null;
 90       if (parent instanceof Frame)
 91          owner = (Frame) parent;
 92       else
 93          owner = (Frame) SwingUtilities.getAncestorOfClass(Frame.class, parent);
 94 
 95       // if first time, or if owner has changed, make new dialog
 96 
 97       if (dialog == null || dialog.getOwner() != owner)
 98       {
 99          dialog = new JDialog(owner, true);
100          dialog.add(this);
101          dialog.getRootPane().setDefaultButton(okButton);
102          dialog.pack();
103       }
104 
105       // set title and show dialog
106 
107       dialog.setTitle(title);
108       dialog.setVisible(true);
109       return ok;
110    }
111 }

  

1 package dataExchange;
 2 
 3 /**
 4  * A user has a name and password. For security reasons, the password is stored as a char[], not a
 5  * String.
 6  */
 7 public class User
 8 {
 9    private String name;
10    private char[] password;
11 
12    public User(String aName, char[] aPassword)
13    {
14       name = aName;
15       password = aPassword;
16    }
17 
18    public String getName()
19    {
20       return name;
21    }
22 
23    public char[] getPassword()
24    {
25       return password;
26    }
27 
28    public void setName(String aName)
29    {
30       name = aName;
31    }
32 
33    public void setPassword(char[] aPassword)
34    {
35       password = aPassword;
36    }
37 }

  

 

测试程序15

l 在elipse IDE中调试运行教材556页程序12-21、12-2212-23,结合程序运行结果理解程序;

l 掌握文件对话框的用法;

l 记录示例代码阅读理解中存在的问题与疑惑。

package fileChooser;

import java.io.*;
import javax.swing.*;
import javax.swing.filechooser.*;
import javax.swing.filechooser.FileFilter;

/**
 * A file view that displays an icon for all files that match a file filter.
 */
public class FileIconView extends FileView {
    private FileFilter filter;
    private Icon icon;

    /**
     * Constructs a FileIconView.
     * 
     * @param aFilter a file filter--all files that this filter accepts will be
     *                shown with the icon.
     * @param         anIcon--the icon shown with all accepted files.
     */
    public FileIconView(FileFilter aFilter, Icon anIcon) {
        filter = aFilter;
        icon = anIcon;
    }

    public Icon getIcon(File f) {
        if (!f.isDirectory() && filter.accept(f))
            return icon;
        else
            return null;
    }
}

  

package fileChooser;

import java.awt.*;
import java.io.*;

import javax.swing.*;

/**
 * A file chooser accessory that previews images.
 */
public class ImagePreviewer extends JLabel {
    /**
     * Constructs an ImagePreviewer.
     * 
     * @param chooser the file chooser whose property changes trigger an image
     *                change in this previewer
     */
    public ImagePreviewer(JFileChooser chooser) {
        setPreferredSize(new Dimension(100, 100));
        setBorder(BorderFactory.createEtchedBorder());

        chooser.addPropertyChangeListener(event -> {
            if (event.getPropertyName() == JFileChooser.SELECTED_FILE_CHANGED_PROPERTY) {
                // the user has selected a new file
                File f = (File) event.getNewValue();
                if (f == null) {
                    setIcon(null);
                    return;
                }

                // read the image into an icon
                ImageIcon icon = new ImageIcon(f.getPath());

                // if the icon is too large to fit, scale it
                if (icon.getIconWidth() > getWidth())
                    icon = new ImageIcon(icon.getImage().getScaledInstance(getWidth(), -1, Image.SCALE_DEFAULT));

                setIcon(icon);
            }
        });
    }
}

  

package fileChooser;

import java.io.*;

import javax.swing.*;
import javax.swing.filechooser.*;
import javax.swing.filechooser.FileFilter;

/**
 * A frame that has a menu for loading an image and a display area for the
 * loaded image.
 */
public class ImageViewerFrame extends JFrame {
    private static final int DEFAULT_WIDTH = 300;
    private static final int DEFAULT_HEIGHT = 400;
    private JLabel label;
    private JFileChooser chooser;

    public ImageViewerFrame() {
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

        // set up menu bar
        JMenuBar menuBar = new JMenuBar();
        setJMenuBar(menuBar);

        JMenu menu = new JMenu("File");
        menuBar.add(menu);

        JMenuItem openItem = new JMenuItem("Open");
        menu.add(openItem);
        openItem.addActionListener(event -> {
            chooser.setCurrentDirectory(new File("."));

            // show file chooser dialog
            int result = chooser.showOpenDialog(ImageViewerFrame.this);

            // if image file accepted, set it as icon of the label
            if (result == JFileChooser.APPROVE_OPTION) {
                String name = chooser.getSelectedFile().getPath();
                label.setIcon(new ImageIcon(name));
                pack();
            }
        });

        JMenuItem exitItem = new JMenuItem("Exit");
        menu.add(exitItem);
        exitItem.addActionListener(event -> System.exit(0));

        // use a label to display the images
        label = new JLabel();
        add(label);

        // set up file chooser
        chooser = new JFileChooser();

        // accept all image files ending with .jpg, .jpeg, .gif
        FileFilter filter = new FileNameExtensionFilter("Image files", "jpg", "jpeg", "gif");
        chooser.setFileFilter(filter);

        chooser.setAccessory(new ImagePreviewer(chooser));

        chooser.setFileView(new FileIconView(filter, new ImageIcon("palette.gif")));
    }
}

  

 

测试程序16

l 在elipse IDE中调试运行教材570页程序12-24,结合运行结果理解程序;

l 了解颜色选择器的用法。

l 记录示例代码阅读理解中存在的问题与疑惑。

1 package colorChooser;
 2 
 3 import java.awt.*;
 4 import javax.swing.*;
 5 
 6 /**
 7  * @version 1.04 2015-06-12
 8  * @author Cay Horstmann
 9  */
10 public class ColorChooserTest
11 {
12    public static void main(String[] args)
13    {
14       EventQueue.invokeLater(() -> {
15          JFrame frame = new ColorChooserFrame();
16          frame.setTitle("ColorChooserTest");
17          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
18          frame.setVisible(true);
19       });
20    }
21 }

  

1 package colorChooser;
 2 
 3 import java.awt.Color;
 4 import java.awt.Frame;
 5 import java.awt.event.ActionEvent;
 6 import java.awt.event.ActionListener;
 7 
 8 import javax.swing.JButton;
 9 import javax.swing.JColorChooser;
10 import javax.swing.JDialog;
11 import javax.swing.JPanel;
12 
13 /**
14  * A panel with buttons to pop up three types of color choosers
15  */
16 public class ColorChooserPanel extends JPanel
17 {
18    public ColorChooserPanel()
19    {
20       JButton modalButton = new JButton("Modal");
21       modalButton.addActionListener(new ModalListener());
22       add(modalButton);
23 
24       JButton modelessButton = new JButton("Modeless");
25       modelessButton.addActionListener(new ModelessListener());
26       add(modelessButton);
27 
28       JButton immediateButton = new JButton("Immediate");
29       immediateButton.addActionListener(new ImmediateListener());
30       add(immediateButton);
31    }
32 
33    /**
34     * This listener pops up a modal color chooser
35     */
36    private class ModalListener implements ActionListener
37    {
38       public void actionPerformed(ActionEvent event)
39       {
40          Color defaultColor = getBackground();
41          Color selected = JColorChooser.showDialog(ColorChooserPanel.this, "Set background",
42                defaultColor);
43          if (selected != null) setBackground(selected);
44       }
45    }
46 
47    /**
48     * This listener pops up a modeless color chooser. The panel color is changed when the user
49     * clicks the OK button.
50     */
51    private class ModelessListener implements ActionListener
52    {
53       private JDialog dialog;
54       private JColorChooser chooser;
55 
56       public ModelessListener()
57       {
58          chooser = new JColorChooser();
59          dialog = JColorChooser.createDialog(ColorChooserPanel.this, "Background Color",
60                false /* not modal */, chooser, 
61                event -> setBackground(chooser.getColor()), 
62                null /* no Cancel button listener */);
63       }
64 
65       public void actionPerformed(ActionEvent event)
66       {
67          chooser.setColor(getBackground());
68          dialog.setVisible(true);
69       }
70    }
71 
72    /**
73     * This listener pops up a modeless color chooser. The panel color is changed immediately when
74     * the user picks a new color.
75     */
76    private class ImmediateListener implements ActionListener
77    {
78       private JDialog dialog;
79       private JColorChooser chooser;
80 
81       public ImmediateListener()
82       {
83          chooser = new JColorChooser();
84          chooser.getSelectionModel().addChangeListener(
85                event -> setBackground(chooser.getColor()));
86 
87          dialog = new JDialog((Frame) null, false /* not modal */);
88          dialog.add(chooser);
89          dialog.pack();
90       }
91 
92       public void actionPerformed(ActionEvent event)
93       {
94          chooser.setColor(getBackground());
95          dialog.setVisible(true);
96       }
97    }
98 }

  

 1 package colorChooser;
 2 
 3 import javax.swing.*;
 4 
 5 /**
 6  * A frame with a color chooser panel
 7  */
 8 public class ColorChooserFrame extends JFrame
 9 {
10    private static final int DEFAULT_WIDTH = 300;
11    private static final int DEFAULT_HEIGHT = 200;
12 
13    public ColorChooserFrame()
14    {      
15       setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
16 
17       // add color chooser panel to frame
18 
19       ColorChooserPanel panel = new ColorChooserPanel();
20       add(panel);
21    }
22 }

  

 

实验总结:在调用超类构造器时,需要提供拥有者框架,对框标题集模式特征。

拥有者框架控制对话框的显示位置,如果将拥有者标识为null,那么对话框将由一个隐藏框架所拥有。

本次实例代码中,之建立了一次对话框,无论何时用户点击About按钮,都可以重要实验它。

 

posted @ 2018-12-02 16:12  白玛次仁  阅读(175)  评论(0编辑  收藏  举报