java 实现局域网 上网代理

1.设置java环境

2.编译下面的类

3.运行.class 文件  在dos 中运行

4.在其它局域网想上网的电脑IE设置

Internet Explorer--->属性-->连接--->局域网设置-->运行代理（能上网的电脑）IP 加端口号;

实现类

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

public class HttpProxy extends Thread {
    static public int CONNECT_RETRIES=5;
    static public int CONNECT_PAUSE=5;
    static public int TIMEOUT=50;
    static public int BUFSIZ=1024;
    static public boolean logging = false;
    static public OutputStream log=null;
    // 传入数据用的Socket
    protected Socket socket;
    // 上级代理服务器，可选
    static private String parent=null;
    static private int parentPort=-1;
    static public void setParentProxy(String name, int pport) {
 parent=name;
 parentPort=pport;
    }

    // 在给定Socket上创建一个代理线程。
    public HttpProxy(Socket s) { socket=s; start(); }

    public void writeLog(int c, boolean browser) throws IOException {
// log.write(c);
    }

    public void writeLog(byte[] bytes,int offset, int len, boolean browser) throws IOException {
// for (int i=0;i<len;i++) writeLog((int)bytes[offset+i],browser);
    }

    // 默认情况下，日志信息输出到
    // 标准输出设备
    // 派生类可以覆盖它
    public String processHostName(String url, String host, int port, Socket sock) {
 java.text.DateFormat cal=java.text.DateFormat.getDateTimeInstance();
// System.out.println(cal.format(new java.util.Date()) + " - " + url + " "
//              + sock.getInetAddress()+"/n");
 return host;
    }

    // 执行操作的线程
    public void run() {
 String line;
 String host;
 int port=80;
        Socket outbound=null;
 try {
     socket.setSoTimeout(TIMEOUT);
     InputStream is=socket.getInputStream();
     OutputStream os=null;
     try {
                // 获取请求行的内容
  line="";
  host="";
  int state=0;
  boolean space;
  while (true) {
      int c=is.read();
      if (c==-1) break;
      if (logging) writeLog(c,true);
      space=Character.isWhitespace((char)c);
      switch (state) {
      case 0:
   if (space) continue;
          state=1;
      case 1:
   if (space) {
       state=2;
       continue;
   }
   line=line+(char)c;
   break;
      case 2:
   if (space) continue; // 跳过多个空白字符
            state=3;
      case 3:
   if (space) {
       state=4;
                            // 只取出主机名称部分
       String host0=host;
       int n;
       n=host.indexOf("//");
       if (n!=-1) host=host.substring(n+2);
       n=host.indexOf('/');
       if (n!=-1) host=host.substring(0,n);
                            // 分析可能存在的端口号
       n=host.indexOf(":");
       if (n!=-1) {
    port=Integer.parseInt(host.substring(n+1));
    host=host.substring(0,n);
       }
       host=processHostName(host0,host,port,socket);
       if (parent!=null) {
    host=parent;
    port=parentPort;
       }
       int retry=CONNECT_RETRIES;
       while (retry--!=0) {
    try {
        outbound=new Socket(host,port);
        break;
    } catch (Exception e) { }
                                // 等待
    Thread.sleep(CONNECT_PAUSE);
       }
       if (outbound==null) break;
       outbound.setSoTimeout(TIMEOUT);
       os=outbound.getOutputStream();
       os.write(line.getBytes());
       os.write(' ');
       os.write(host0.getBytes());
       os.write(' ');
       pipe(is,outbound.getInputStream(),os,socket.getOutputStream());
       break;
   }
   host=host+(char)c;
   break;
      }
  }
     }
     catch (IOException e) { }

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

    void pipe(InputStream is0, InputStream is1,
         OutputStream os0,  OutputStream os1) throws IOException {
 try {
     int ir;
     byte bytes[]=new byte[BUFSIZ];
     while (true) {
  try {
      if ((ir=is0.read(bytes))>0) {
   os0.write(bytes,0,ir);
   if (logging) writeLog(bytes,0,ir,true);
      }
      else if (ir<0)
   break;
  } catch (InterruptedIOException e) { }
  try {
      if ((ir=is1.read(bytes))>0) {
   os1.write(bytes,0,ir);
   if (logging) writeLog(bytes,0,ir,false);
      }
      else if (ir<0)
   break;
  } catch (InterruptedIOException e) { }
     }
 } catch (Exception e0) {
//     System.out.println("Pipe异常: " + e0);
 }
    }

    static public void startProxy(int port,Class clobj) {
 ServerSocket ssock;
 Socket sock;
        try {
     ssock=new ServerSocket(port);
     while (true) {
  Class [] sarg = new Class[1];
  Object [] arg= new Object[1];
  sarg[0]=Socket.class;
  try {
      java.lang.reflect.Constructor cons = clobj.getDeclaredConstructor(sarg);
      arg[0]=ssock.accept();
      cons.newInstance(arg); // 创建HttpProxy或其派生类的实例
  } catch (Exception e) {
      Socket esock = (Socket)arg[0];
      try { esock.close(); } catch (Exception ec) {}
  }
     }
 } catch (IOException e) {
 }
    }

    // 测试用的简单main方法
    static public void main(String args[]) {
 System.out.println("在端口808启动代理服务器/n");
 HttpProxy.log=System.out;
 HttpProxy.logging=false;
 HttpProxy.startProxy(808,HttpProxy.class);
      }
    }