httpproxy.java

《Java TCP/IP应用开发详解》的部分源程序,开发环境为ECLIPSE3.1

package section18;

import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InterruptedIOException;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class HttpProxy extends Thread {
  static public int CONNECT_RETRIES=5;
  static public int CONNECT_PAUSE=5;
  static public int TIMEOUT=500;
  static public int BUFSIZE=1024;
  static public boolean logging=true;
  static public OutputStream log=null;
  public String head="";
  protected Socket socket;
  
  public HttpProxy(Socket s)
  {
	  socket=s;
	  
  }
	
  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
	  {
		  socket.setSoTimeout(TIMEOUT);
		  InputStream is=socket.getInputStream();
		  host=getHost(is);
		  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);
			      while(retry--!=0)
			      {
			    	  try{
			    		  outbound=new Socket(host,port);
			    		  break;
			    	  }catch(Exception e)
			    	  {
			    		  e.printStackTrace();
			    	  }
			      try{
			    	  Thread.sleep(CONNECT_PAUSE);
			      }catch(InterruptedException e){e.printStackTrace();} 
					
				
			      
			      }
			  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(IOException 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);
		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[BUFSIZE];
			while(true)
			{
				try{
					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
			{
				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 ssocket;
		Socket socket;
		try{
			ssocket=new ServerSocket(port);
			while(true)
			{
				socket=ssocket.accept();
				new HttpProxy(socket).start();
			}
		}catch(Exception e)
		{
			e.printStackTrace();
		}
	}
	
}