实现一个简单的日历

利用Java写一个简易的日历

 

//构造窗体中的内容
package practice;

import java.awt.Color;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import java.util.Calendar;
import javax.swing.JPanel;

public class myPanel extends JPanel{

    public myPanel()
    {

    }

    @Override
    protected void paintComponent(Graphics g)
    {

        int width = this.getWidth();
        int height = this.getHeight();
        Graphics2D g2d = (Graphics2D) g;

        //平滑绘制反锯齿
        g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);//设置一个单独的渲染算法
        g2d.setPaint(Color.white);
        g2d.fillRect(0, 0, width, height);

        int x = 0;
        int y = 0;
        int x_size = 100;//单元格宽度
        int y_size = 80;//单元格高度

        //第一行，显示一二三四五六日
        g2d.setPaint(Color.GRAY);
        g2d.drawLine(x, y,x + x_size * 7, y);
        g2d.drawLine(x, y+y_size, x_size*7, y+y_size);
        String [] cc = {"一","二","三","四","五","六","日"};

        g2d.setPaint(Color.GRAY);
        g2d.setFont(new Font("宋体",0,20));
        for(int i = 0; i < 7;i++)
        {
            Rectangle rect =new Rectangle(x+i*x_size, y, x_size, y_size);
            drawText(g2d,cc[i],rect);
        }

        //计算本月第一天是星期几
        Calendar cal = Calendar.getInstance();
        int theYear = cal.get(Calendar.YEAR);
        int theMonth = cal.get(Calendar.MONTH);//当前月份
        int theDay = cal.get(Calendar.DAY_OF_MONTH);//当前几号
        cal.set(Calendar.DAY_OF_MONTH, 1);//向前推到本月第一号
        int weekday = cal.get(Calendar.DAY_OF_WEEK);//计算本月第一天是星期几
        System.out.println("week:"+weekday);

//			//第几周转换为英文
			String weekDay = null ;
			switch(weekday)
			{
				case 1: weekDay = "monday"  ; break;
				case 2: weekDay = "tuesday" ; break;
				case 3: weekDay = "wednesday"  ; break;
				case 4: weekDay = "thursday" ; break;
				case 5: weekDay = "friday"  ; break;
				case 6: weekDay = "saturdy"  ; break;
				case 7: weekDay = "sunday"  ; break;
				default: break;
			}
			System.out.println("today is " + theYear +"/" + theMonth + "/" + theDay );
			System.out.println("and today is " + weekDay);

        //往前推N天
        //Calendar里规定Sunday是第一天，
        //他是周一，前推0天，周二推一天，周五推4天，周日推6天
        int start = weekday - Calendar.MONDAY;
        if(start < 0) start = 6;
        cal.add(Calendar.DAY_OF_MONTH, 0 - start);

        //绘制五行
        //每月最多31天，分五行显示
        x = 0;
        y += y_size;
        for(int i = 0;i < 6 ;i++)//6行
        {
            for(int j = 0;j < 7;j++)//7列
            {
                //判断月份是否相同
                if(cal.get(Calendar.MONTH) == theMonth)
                {
                    g2d.setPaint(Color.BLACK);
                }
                else
                {
                    g2d.setPaint(Color.GRAY);
                }
                int day = cal.get(Calendar.DAY_OF_MONTH);
                Rectangle rect = new Rectangle(x+x_size*j,y+y_size*i,x_size,y_size);
                drawText(g2d,String.valueOf(day),rect);

                //日期加一
                cal.add(Calendar.DAY_OF_MONTH, 1);

            }
        }



    }


    //将str绘制在矩形rent中，居中显示
    private void drawText(Graphics2D g2d, String str, Rectangle rect)
    {
        FontMetrics fm = g2d.getFontMetrics();
        int fontSize = fm.getHeight();//字高
        int textWidth = fm.stringWidth(str);//获取字宽
        int leading = fm.getLeading();
        int ascent = fm.getAscent();
        int descent = fm.getDescent();
        System.out.println(fontSize + "," + leading + "," + ascent + "," + descent );

        int x = 0;
        int y = 0;
        x = rect.x + (rect.width - textWidth)/2;//水平居中
        y = rect.y + rect.height / 2  + (fontSize -leading)/2 -descent;
        g2d.drawString(str, x, y);

    }


}

//创建按钮
package practice;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import javax.swing.*;
import javax.swing.border.Border;

public class myFrame extends JFrame{

    myPanel p = new myPanel();


    public myFrame(String title)
    {
        super(title);

        Container root = this.getContentPane();//创建一个容器
        root.setLayout(new BorderLayout());//定义布局方式

        root.add(p,BorderLayout.CENTER);//将对象p放置在中间
		//设置边框
		Border border = BorderFactory.createLineBorder(Color.BLUE,2,true);//用蓝色绘制一个行边界。
		p.setBorder(border);//将设置好的边界显示出来


		JButton button1 = new JButton();//创建按钮对象
		button1.setText("我的日历");//设置按钮文本
        //button1.addActionListener(new ActionListener(){
          //                      public void acctionPerformed(ActionEvent e){
//弹出对话框
            //                        JOptionPane.showMessageDialog(null,"hello world");
              //                  }
                //            });
		root.add(button1,BorderLayout.PAGE_START);//将按钮添加到容器中

		//将窗体设置为居中显示
      this.setSize(600,600);
      this.setLocationRelativeTo(null);

    }

}

package practice;

import javax.swing.JFrame;

public class SwingDemo {

    public static void main(String[] args)
    {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {//事件分发线程，来保证GUI在事件分发线程中创建

            //@Override
            public void run()
            {
                createGUI();
            }

        });
    }

    private static void createGUI()
    {
        myFrame frame = new myFrame("日历");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//设置窗体关闭方式

        frame.setSize(800,600);//设置窗体大小
        frame.setVisible(true);//使窗体可见
    }

}