httpproxy.java

一个很好的学生成绩管理系统

import java.net.*;
import java.io.*;

//代理服务的线程服务类
public class HttpProxy extends Thread 
{
    //尝试对远程连接的次数
    static public int CONNECT_RETRIES=5;
    //间隔多少时间尝试一次对远程连接
    static public int CONNECT_PAUSE=5;
    //等待用户从浏览器发布数据的时间
    static public int TIMEOUT=500;
    //socket的输入缓冲
    static public int BUFSIZ=1024;
    //log标识
    static public boolean logging = true;
    //log信息的输出流
    static public OutputStream log=null;
   
   public String head="";
   
    protected Socket socket;
    

    //初始化并启动代理服务
    public HttpProxy(Socket s) 
    { 
    	socket=s; 
    }


    //写日志信息
    public void writeLog(byte[] bytes,int offset, int len) throws IOException 
    {
	for (int i=offset;i<len;i++) 
	{	

		log.write((int)bytes[i]);	
	}
    }



    public void run() 
    {
	String line;
	String host;
	int port=80;
        Socket outbound=null;
	try 
	{
	    //超时时间为TIMEOUT毫秒
	    socket.setSoTimeout(TIMEOUT);
	    //得到socket输入流
	    InputStream is=socket.getInputStream();
	    host=getHost(is);
	    //OutputStream os=socket.getOutputStream();
	    try 
	    {
		while (true) 
		{
			
			int n=-1;
			n=host.indexOf(":");
			if (n!=-1) 
			{ 
				port=Integer.parseInt(host.substring(n+1));
				host=host.substring(0,n);
	
			}
			int retry=CONNECT_RETRIES;   
			System.out.println("host is "+host);
			//连接重试
			while (retry--!=0) 
			{
			 	try
			 	{
				 	//和远程主机建立连接
				 	outbound=new Socket(host,port);
				 	break;
				}
				catch (Exception e)
				{
					e.printStackTrace(); 
				}
				
				//没间隔一段时间，尝试一次连接
				Thread.sleep(CONNECT_PAUSE);
			 }
			    
			 if (outbound==null) break;
			     
			 outbound.setSoTimeout(TIMEOUT);
			 OutputStream  os1=outbound.getOutputStream();
			 
			 byte[] bytes=head.getBytes();
			 os1.write(bytes,0,bytes.length);
			    
			 pipe(socket.getInputStream(),outbound.getInputStream(),socket.getOutputStream(),os1);
			 break;
		}
	    }
	    catch (IOException e) { }

	} 
	catch (Exception e) { }
    	finally 
    	{
		    try { socket.close();} 
		    catch (Exception e1) {e1.printStackTrace();}
		    try { outbound.close();} 
		    catch (Exception e2) {e2.printStackTrace();}
       	}
    }

    public String getHost(InputStream is) throws IOException 
    {
    	String host=null;
    	DataInputStream dis=new DataInputStream(is);
    	//jdk1.3API中readLine方法已经被BufferedReader替换
    	host =dis.readLine();
    	head =host;
	int n=host.indexOf("//");
	if (n!=-1) host=host.substring(n+2);
	n=host.indexOf('/');
	if (n!=-1) host=host.substring(0,n);

	return host;
    }

    void pipe(InputStream is0, InputStream is1,OutputStream os0,  OutputStream os1) throws IOException 
    {
	try 
	{
	    int i;
	    byte bytes[]=new byte[BUFSIZ];
	    while (true) 
	    {
		try 
		{
		    //将客户端输入流写入服务端输出流
		    //如果inputstream没有数据read方法阻塞
		    if ((i=is0.read(bytes))>0) 
		    {
			os1.write(bytes,0,i);
			
			if (logging) writeLog(bytes,0,i);
		    }
		    else if (i<0)
			break;
		} 
		catch (InterruptedIOException e) { }
		
		try 
		{
		    //将服务端输入流写入客户端输出流
		    //如果inputstream没有数据,read方法阻塞
		    if ((i=is1.read(bytes))>0) 
		    {
			os0.write(bytes,0,i);
			if (logging) writeLog(bytes,0,i);
		    }
		    else if (i<0) 
			break;
		} 
		catch (InterruptedIOException e) 
		{ 
			e.printStackTrace();
		}
	    }
	} 
	catch (Exception e) 
	{
	    System.out.println("Pipe Exception: " + e);
	    e.printStackTrace();
	}
    }


    static public void main(String args[]) 
    {
	System.out.println("Starting proxy on port 808");
	int port = 808;
	HttpProxy.log=System.out;
	HttpProxy.logging=true;
	ServerSocket ssock;
	Socket sock;
        try 
        {
	    ssock=new ServerSocket(port);
	    while (true) 
	    {
		    sock =ssock.accept();
		    (new HttpProxy(sock)).start();
	    }
	} 
	catch (Exception e) 
	{
		e.printStackTrace();
	}
    }
}