一个基础的代理服务器类

/*************************************
 * 一个基础的代理服务器类
 *************************************
 */
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);
      }
    }