screenprotect.java

一个java编写的屏幕保护程序,有助于学习applet图形编程.

import java.applet.Applet;
import java.awt.*;
import java.util.Random;


public class ScreenProtect extends Applet implements Runnable{


	int circle_x = 0;//左上角
	int circle_y = 0;
	int range = 0;   //范围
	int r = 0;       //半径
	int ranx= 100;//圆心坐标
	int rany = 100;
	Color circle_c = Color.WHITE;
	Color c = Color.BLUE;
	Random rand = new Random();
	
	
    public void init(){
    }
	
	public void start()
	{
		Thread t = new Thread(this);
		t.start();

	}
	
	public void update(Graphics g)
	{
		this.paint(g);
	}
	
	public void paint(Graphics g)
	{
		g.setColor(circle_c);
		g.fillOval(circle_x, circle_y, range, range);
	}
	
	public void run()
	{

		while(true){
			if(r == 200 || r == 0)
			{
			    	circle_c = Color.WHITE;
					circle_x = ranx - r/2;
					circle_y = rany - r/2;
					range = r;
					repaint();
					ranx = 100 + rand.nextInt(400);
					rany = 100 + rand.nextInt(400);
					c = new Color(rand.nextInt(255), rand.nextInt(255), rand.nextInt(255));
				r = 0;
			}
		    	circle_c = c;
				circle_x = ranx - r/2;
				circle_y = rany - r/2;
				range = r;
				repaint();
				r += 2;	
				
			try {
				Thread.sleep(10);
			}
			catch (InterruptedException e)
			{
			}
			
	
		}
	}


}