【Java GUI】简单铅笔画图程序

文件组织

代码

package drawboard;

import javax.swing.JFrame;

public class DrawBoard {
public static void main(String[] args) {
DrawBoardFrame db=new DrawBoardFrame();
db.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

}

package drawboard;
import javax.swing.*;
public class DrawBoardFrame extends JFrame{
public static final int DEFAULT_W=600;
public static final int DEFAULT_H=500;

public  DrawBoardFrame(){
setTitle("画　板");
setSize(DEFAULT_W,DEFAULT_H);
DrawBoardPanel panel=new DrawBoardPanel();
getContentPane().add(panel);
setVisible(true);

}
}

package drawboard;
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.geom.Line2D;
import javax.swing.*;

public class DrawBoardPanel extends JPanel{
int x1,y1,
x2,y2;

public DrawBoardPanel(){
addMouseMotionListener(new MouseMotionListener() {
public void mouseDragged(MouseEvent e) {
Graphics2D g=(Graphics2D)getGraphics();
//获取鼠标位置
x2=e.getX();y2=e.getY();
g.draw(new Line2D.Double(x1,y1,x2,y2));
x1=x2;y1=y2;
g.dispose();
}
public void mouseMoved(MouseEvent e) {
double tx=e.getX();
double ty=e.getY();
System.out.println("鼠标当前坐标：（"+tx+","+ty+')');
};

});

addMouseListener(new MouseAdapter(){
public void mousePressed(MouseEvent e){
x1=e.getX();y1=e.getY();
}
});

}
}

效果

PS:较早时候写的，可能不符合现在的规范，仅作参考。