AWT--事件监听与输入框监听

事件监听与输入框监听

事件监听

1. 事件监听：当某个事件发生的时候，干什么？

package com.deng.lesson2;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class TestActionEvent {
    public static void main(String[] args) {
        //按下按钮，触发一些事件
        Button button = new Button();
        Frame frame = new Frame();
        //因为addActionListener()需要一个ActionListener，所以我们需要构造一个ActionListener
        MyActionListener myActionListener = new MyActionListener();
        button.addActionListener( myActionListener );

        frame.add(button,BorderLayout.CENTER);
        frame.pack();
        frame.setVisible(true);
        windowClose(frame);//关闭窗口
    }
    //关闭窗口事件
    private static void windowClose(Frame frame){
        frame.addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                super.windowClosing(e);
                System.exit(0);
            }
        });
    }
}
//事件监听
 class MyActionListener implements ActionListener {

     @Override
     public void actionPerformed(ActionEvent e) {
         System.out.println("aaa");
     }
 }

2. 多个按钮共享一个事件

package com.deng.lesson2;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class TestActionTwo {
    public static void main(String[] args) {
        //两个按钮 实现同一个监听
        //开始  停止
        Frame frame = new Frame("开始-停止");
        Button button1 = new Button("start");
        Button button2 = new Button("stop");

        //可以显示的定义触发会返回的命令， 如果不显示定义，则会走默认值
        //可以多个按钮只写一个监听类
        button2.setActionCommand("button2-stop");

        MyMonitor myMonitor = new MyMonitor();
        button1.addActionListener(myMonitor);
        button2.addActionListener(myMonitor);

        frame.add(button1,BorderLayout.NORTH);
        frame.add(button2,BorderLayout.SOUTH);
        frame.pack();
        frame.setVisible(true);

    }
}
class MyMonitor implements ActionListener{
    @Override
    public void actionPerformed(ActionEvent e) {
        //e.getActionCommand() 获得按钮的信息
        System.out.println("按钮被点击了：msg=>"+e.getActionCommand());
    }
}

输入框 TextField 监听

package com.deng.lesson2;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class TestText1 {
    public static void main(String[] args) {
        //启动
        new MyFrame();
    }
}
class MyFrame extends Frame {
    public MyFrame() {
        TextField textField = new TextField();
        add(textField);

        //监听这个文本框输入的文字
        MyActionListener2 myActionListener2 = new MyActionListener2();
        //按下enter就会触发这个输入框事件
        textField.addActionListener(myActionListener2);

        //设置替换密码
        textField.setEchoChar('*');

        setVisible(true);
        pack();

        //关闭事件窗口
        addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosing(WindowEvent e) {
                super.windowClosing(e);
                System.exit(0);
            }
        });
    }

    class MyActionListener2 implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
            TextField Field = (TextField) e.getSource();//获得一些资源，返回的一个对象
            System.out.println(Field.getText());//获得输入框文本
            Field.setText("");//null
        }
    }
}