example14_15.java

不错的教程 适合中高级人员的使用

import java.awt.*;import java.awt.image.*;
import java.awt.event.*;import com.sun.image.codec.jpeg.*;
import java.util.*;import java.io.*;
class PaintCanvas extends Canvas 
{  int x=-1,y=-1;
   Vector v=new Vector();
   BufferedImage image;
   Graphics2D g2D;
   PaintCanvas()
   { 
	 
	 image=new BufferedImage(300,300,BufferedImage.TYPE_INT_RGB);
     g2D=image.createGraphics();
	 //g2D.setColor(Color.white);g2D.fillRect(0,0,300,300);//把背景变成白色
	 //g2D.setColor(Color.black);
	 addMouseMotionListener(new MouseMotionAdapter()
	   {
		 public void mouseDragged(MouseEvent e)
		   {x=(int)e.getX();y=(int)e.getY();
		    Point p=new Point(x,y);
			v.addElement(p);
			if(x!=-1&&y!=-1)
			   {
				for(int i=0;i<v.size()-1;i++)
				   {Point p1=(Point)v.elementAt(i);
				    Point p2=(Point)v.elementAt(i+1);
					g2D.drawLine(p1.x,p1.y,p2.x,p2.y);				    
				}
				repaint();
			}
		 }
	 }
	);
	addMouseListener(new MouseAdapter()
	   {public void mouseReleased(MouseEvent e)
		   {v.removeAllElements();}
	}
		);
   }
   public void paint(Graphics g)
   {
     g.drawImage(image,0,0,this);
   }
   public void update(Graphics g)
	{paint(g);}
}

class WindowCanvas extends Frame implements ActionListener
{
	PaintCanvas canvas=new PaintCanvas();
	Button button=new Button("save");
	WindowCanvas()
	{
		button.addActionListener(this);
		add(button,BorderLayout.NORTH);
		add(canvas,BorderLayout.CENTER);
		setBounds(100,100,400,400);
		setVisible(true);
		addWindowListener(new WindowAdapter()
		{
			public void windowClosing(WindowEvent e)
			{
				System.exit(0);
			}
		}
		);
	}
	public void actionPerformed(ActionEvent e)
	{
		try{JPEGImageEncoder encoder=JPEGCodec.createJPEGEncoder(new FileOutputStream("A.jpg"));
		     encoder.encode(canvas.image);
			}
		catch(Exception ee)	{}
	}
}
public class Example14_15
{ public static void main(String args[])
  {new WindowCanvas();
   }
}