日期:2014-05-20  浏览次数:20884 次

swing的一段代码,貌似是焦点的问题,求指教
Java code

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

class DrawPic extends JFrame implements MouseListener,MouseMotionListener{
    int x1,x2,y1,y2;
    boolean line,circle,rect;
    static CheckboxGroup cbg ;
    DrawPic(){
        addMouseListener(this);
        x1 = 0;
        x2 = 0;
        y1 = 0;
        y2 = 0;
        line = false;
        circle = false;
        rect = false;
    }
    public void go(){
      setLayout(new GridLayout(3,1));
      cbg = new CheckboxGroup();
      add(new Checkbox("line",cbg,true));
      add(new Checkbox("rect",cbg,false));
      add(new Checkbox("circle",cbg,false));
   }
    public static void main(String args[]){
        DrawPic draw = new DrawPic();
        draw.setSize(400,300);
        //draw.go();
        draw.setVisible(true);
    }
    public void mouseClicked(MouseEvent e){
        System.out.println("Mouse Clicked");
    }
    public void mouseReleased(MouseEvent e){
        x2 = e.getX();
        y2 = e.getY();
        /*if(cbg.getSelectedCheckbox().getLabel().equals("line"))
            line = true;
        else if(cbg.getSelectedCheckbox().getLabel().equals("rect"))
            rect = true;
        else if(cbg.getSelectedCheckbox().getLabel().equals("circle"))
            circle = true;*/
        repaint();
        line = false;
        circle = false;
        rect = false;
    }
    public void mouseEntered(MouseEvent e){}
    public void mouseExited(MouseEvent e){}
    public void mousePressed(MouseEvent e){
        x1 = e.getX();
        y1 = e.getY();
    }
    public void mouseDragged(MouseEvent e){
        
    }
    public void mouseMoved(MouseEvent e){}
    public void paint(Graphics g){
        System.out.println("painting..");
        line = true;
        g = this.getContentPane().getGraphics();
        if(line)
            g.drawLine(x1,y1,x2,y2);
        else if(circle)
            g.drawOval(x1,y1,x2-x1,y2-y1);
        else if(rect)
            g.drawRect(x1,y1,x2-x1,y2-y1);
    }
}




------解决方案--------------------
三个checkbox占据了整个frame而他们是不会响应你的mouseevent的
加一个panel在第一行,然后2 3 行中进行操作
代码稍微改了下可以运行
Java code
/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package test;

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

class DrawPic extends JFrame implements MouseListener,MouseMotionListener{
    int x1,x2,y1,y2;
    boolean line,circle,rect;
    static CheckboxGroup cbg ;
    DrawPic(){
        addMouseListener(this);
        x1 = 0;
        x2 = 0;
        y1 = 0;
        y2 = 0;
        line = false;
        circle = false;
        rect = false;
        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
    }
    public void go(){
      setLayout(new GridLayout(3,1));
      JPanel pnl = new JPanel();
      add(pnl);     
      cbg = new CheckboxGroup();

      pnl.add(new Checkbox("line",cbg,true));
      pnl.add(new Checkbox("rect",cbg,false));
      pnl.add(new Checkbox("circle",cbg,false));

   }
    public static void main(String args[]){
        DrawPic draw = new DrawPic();
        draw.setSize(400,300);
        draw.go();
        draw.setVisible(true);
    }
    public void mouseClicked(MouseEvent e){
        System.out.println("Mouse Clicked");
    }
    public void mouseReleased(MouseEvent e){
        x2 = e.getX();
        y2 = e.getY();
        line = false;
        circle = false;
        rect = false;
        if(cbg.getSelectedCheckbox().getLabel().equals("line"))
            line = true;
        else if(cbg.getSelectedCheckbox().getLabel().equals("rect"))
            rect = true;
        else if(cbg.getSelectedCheckbox().getLabel().equals("circle"))
            circle = true;
        repaint();
        
    }
    public void mouseEntered(MouseEvent e){}
    public void mouseExited(MouseEvent e){}
    public void mousePressed(MouseEvent e){
        x1 = e.getX();
        y1 = e.getY();
    }
    public void mouseDragged(MouseEvent e){
        
    }
    public void mouseMoved(MouseEvent e){}
    public void paint(Graphics g){
        System.out.println("painting..");
        //line = true;
        g = this.getContentPane().getGraphics();
        if(line)
            g.drawLine(x1,y1,x2,y2);
        else if(circle)
            g.drawOval(x1,y1,x2-x1,y2-y1);
        else if(rect)
            g.drawRect(x1,y1,x2-x1,y2-y1);
        else{
            g.drawLine(x1,y1,x2,y2);
        }
    }
}