javaapplet例子

例子1：运行，编译，网页中嵌入的例子

import java.applet.*;

import java.awt.*;

public class Example12_1 extends Applet

{ Button button1,button2;

int sum;

public void init()

{ setBackground(Color.gray);

button1=new Button("yes");

button2=new Button("No");

add(button1);

add(button2);

}

public void start()

{ sum=0;

for(int i=1;i<=100;i++)

{ sum=sum+i;

}

}

public void stop() { }

public void paint(Graphics g)

{ g.setColor(Color.blue);

g.drawString("程序设计方法",20,60);

g.setColor(Color.red);

g.drawString("sum="+sum,20,100);

}

}

例子2：网页向JavaApplet传值

import java.awt.*;

import java.applet.*;

public class Example12_2 extends Applet

{ int x=0,y=0;

public void init()

{ String s1=getParameter("girl");//从html得到"girl"的值。

String s2=getParameter("boy");//从html得到"boy"的值。

x=Integer.parseInt(s1);

y=Integer.parseInt(s2);

}

public void paint(Graphics g)

{ g.drawString("x="+x+","+"y="+y,90,120);

}

}

Boy.html

例子3：JavaApplet中使用URL

import java.applet.*;

import java.awt.*;

import java.awt.event.*;

import .*;

public class Boy extends Applet implements ActionListener { Button button;

URL url;

TextField text;

public void init()

{ text=new TextField(18);

button=new Button(“确定”);

add(new Label(“输入网址:”));

add(text); add(button);

button.addActionListener(this);

}

public void actionPerformed(ActionEvent e)

{ if(e.getSource()==button)

{ try { url=new URL(text.getText().trim());

getAppletContext().showDocument(url);

}

catch(MalformedURLException g)

{ text.setText(“不正确的URL:"+url);

}

}

}

}

例子4：建立新线程

import java.applet.*;

import java.awt.*;

import .*;

import java.io.*;

public class ReadFile extends Applet

{ TextArea text;

URL url;

public void init()

{ text=new TextArea(12,40);

add(text);

}

public void start()

{ try { url=new URL(getCodeBase(),"hello.txt");

InputStream in=url.openStream(); //url返回输入流 int n=-1;

byte b[]=new byte[100];

while((n=in.read(b))!=-1)

{ String str=new String(b,0,n);

text.append(str);

}

}

catch(Exception ee) {}

}

}

例子5：使用套接字

import java.applet.*;

import java.awt.*;

import java.awt.event.*;

public class CircleAndRect extends

Applet implements Runnable

{ Thread left ,right;

Graphics mypen;

int x,y;

public void init()

{ left=new Thread(this);

right=new Thread(this);

x=10;y=10;

mypen=getGraphics();

}

public void start()

{ try { left.start();

right.start();

}

catch(Exception e){}

}

public void run()

{ while(true)

{ if(Thread.currentThread()==left)

{ x=x+1;

if(x>240) x=10;

mypen.setColor(Color.blue);

mypen.clearRect(10,10,300,40);

mypen.drawRect(10+x,10,40,40);

try{ left.sleep(60);

}

catch(InterruptedException e){}

}

else if(Thread.currentThread()==right)

{ y=y+1;

if(y>240) y=10; mypen.setColor(Color.red);

mypen.clearRect(10,90,300,40);

mypen.drawOval(10+y,90,40,40);

try{ right.sleep(60);