java实现http代理服务详解编程语言

    package httpProxy;   
/*************************************  
* 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   
static public 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;   
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) {   
}   
}   
static public void stopProxy(){   
try {   
if(null!=HttpProxy.socket)   
HttpProxy.socket.close();   
} catch (IOException e) {   
e.printStackTrace();   
}   
}   
// 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);   
}   
}  

来自：http://chenyu-hz.iteye.com/blog/1493227