JAVA实现网络请求代理之HTTP篇
JAVA实现网络请求代理之HTTP篇 (一)
JAVA实现网络请求代理之Socket篇(二)
Java代理服务器之截取，篡改HTTP请求（应用篇）
首先，需要弄明白代理服务的原理，和http协议几种请求类型的构成。
代理服务器原理
http协议详解
1、请求行以一个方法符号开头，以空格分开，后面跟着请求的URI和协议的版本，格式如下：
Method RequestURI HTTP-Version CRLF
其中 Method表示请求方法；Request-URI是一个统一资源标识符；HTTP-Version表示请求的HTTP协议版本；CRLF表示回车和换行（除了作为结尾的CRLF外，不允许出现单独的CR或LF字符）。
例如：
GET请求
GET http://www.baidu.com/ HTTP/1.1 注:请求行 【方法 统一资源标识符 HTTP协议版本】
Host: www.baidu.com 注:主机
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:40.0) Gecko/20100101 Firefox/40.0 注:浏览器信息
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 注:返回数据类型
Accept-Language: zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3 注:语言权重值
Accept-Encoding: gzip, deflate 注:压缩格式
Cookie: BAIDUID=528AC525A03A636F088835EED7DFA00F:FG=1; BIDUPSID=F7A856B7B734889B5BB1227150199A90; PSTM=1441605421; BD_UPN=13314752 注:cookie
Connection: keep-alive 注:连接类型
POST请求
POST /foo.php HTTP/1.1
Host: localhost
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US; rv:1.9.1.5) Gecko/20091102 Firefox/3.5.5 (.NET CLR 3.5.30729)
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-us,en;q=0.5
Accept-Encoding: gzip,deflate
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7
Keep-Alive: 300
Connection: keep-alive
Referer: http://localhost/test.php
Content-Type: application/x-www-form-urlencoded
Content-Length: 43 注:内容长度
first_name=John&last_name=Doe&action=Submit 注:提交数据
接下来就介绍如何具体实现HTTP代理服务器。
新建一个处理Http请求的服务线程，监听808端口
package com.mato.proxy.http;
import java.net.ServerSocket;
import java.net.Socket;
/**
* Created by cjl on 2015/9/8.
*/
public class HttpProxy extends Thread{
private ServerSocket server;
public HttpProxy(ServerSocket _server){
server=_server;
start();
}
public void run(){
// 线程运行函数
Socket connection;
while(true){
try{
connection=server.accept();
//接受到请求，就新建一个处理请求的服务线程，将当前请求传递到线程里面
HTTPServerThread handler =new HTTPServerThread(connection);
}
catch(Exception e){}
}
}
}
接下来就是每一个请求处理线程的处理逻辑
package com.mato.proxy.http;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
/**
* Created by cjl on 2015/9/8.
*/
public class HTTPServerThread extends Thread {
private Socket client;
public HTTPServerThread(Socket _connection) {
client = _connection;
start();
}
public void run() { // 线程运行函数
byte buf[] = new byte[10000], buf1[] = new byte[10000], buf2[] = new byte[10000];
int creadlen = 0, sreadlen = 0;
int i;
String s = null, s1 = null, s2 = null;
Socket server = null;
int port = 80;
DataInputStream cin = null, //客户端输入流
sin = null; //服务端输入流
DataOutputStream cout = null, //客户端输出流
sout = null; //服务端输出流
int method = 0;
try {
cin = new DataInputStream(client.getInputStream());
cout = new DataOutputStream(client.getOutputStream());
if (cin != null && cout != null) {
creadlen = cin.read(buf, 0, 10000); // 从客户端读数据
if (creadlen > 0) { // 读到数据
s = new String(buf);
if (s.indexOf("\r\n") != -1)
s = s.substring(0, s.indexOf("\r\n"));
if (s.indexOf("GET ") != -1)
method = 0;// 如读到 GET 请求
if (s.indexOf("CONNECT ") != -1) {
// 读到 CONNECT 请求 , 返回 HTTP 应答
s1 = s.substring(s.indexOf("CONNECT ") + 8, s.indexOf
("HTTP/"));
s2 = s1;
s1 = s1.substring(0, s1.indexOf(":"));
s2 = s2.substring(s2.indexOf(":") + 1);
s2 = s2.substring(0, s2.indexOf(" "));
port = Integer.parseInt(s2);
method = 1;
sendAck(cout);
}
if (s.indexOf("POST ") != -1)// 如读到 POST 请求
method = 2;
if (s.indexOf("http://") != -1 && s.indexOf("HTTP/") != -1) {
// 从所读数据中取域名和端口号
s1 = s.substring(s.indexOf("http://") + 7, s.indexOf("HTTP/"));
s1 = s1.substring(0, s1.indexOf("/"));
if (s1.indexOf(":") != -1) {
s2 = s1;
s1 = s1.substring(0, s1.indexOf(":"));
s2 = s2.substring(s2.indexOf(":") + 1);
port = Integer.parseInt(s2);
method = 0;
}
}
if (s1 != null) {
server = new Socket(s1, port);
// 根据读到的域名和端口号建立套接字
sin = new DataInputStream(server.getInputStream());
sout = new DataOutputStream(server.getOutputStream());
if (sin != null && sout != null && server != null) {
if (method == 0) {
sreadlen = doGet(buf, creadlen, sin, cout, sout);
}
if (method == 1) { // 如读到 CONNECT 请求
sreadlen = doConnect(buf, sreadlen, cin, sin, cout, sout);
}
if (method == 2) { // 如读到 POST 请求
// 向外网发送 POST 请求
doPost(buf, creadlen, sreadlen, cin, sin, cout, sout);
}
}
}
}
}
// 执行关闭操作
if (sin != null) sin.close();
if (sout != null) sout.close();
if (server != null) server.close();
if (cin != null) cin.close();
if (cout != null) cout.close();
if (client != null) client.close();
} catch (IOException e) {
}
}
/**
* 发生确认
*
* @param cout 输出流
* @throws IOException
*/
private void sendAck(DataOutputStream cout) throws IOException {
String s2;
byte[] buf2;
s2 = "HTTP/1.0 200 Connection established\r\n";
s2 = s2 + "Proxy-agent: proxy\r\n\r\n";
buf2 = s2.getBytes();
cout.write(buf2);
cout.flush();
}
/**
* 处理POST 请求
* @param buf 数据缓存区
* @param creadlen 客户端读取的buf的长度
* @param sreadlen 服务端读取的buf的长度
* @param cin 客户端输入流
* @param sin 服务端输入流
* @param cout 客户端输出流
* @param sout 服务端输出流
* @throws IOException
*/
private void doPost(byte[] buf, int creadlen, int sreadlen, DataInputStream cin, DataInputStream sin, DataOutputStream cout, DataOutputStream sout) throws IOException {
write(buf, creadlen, sout);
// 建立线程 , 用于从外网读数据 , 并返回给内网客户端
HTTPChannel thread1 = new HTTPChannel(sin, cout);
while ((sreadlen = cin.read(buf, 0, 10000))!=-1) { // 循环
try {
System.out.println("post>>"+new String(buf));
if (sreadlen > 0) { // 读到数据 , 则发送给外网
write(buf, sreadlen, sout);
}
} catch (Exception e1) {
break;
}
}
}
/**
* 写数据
* @param buf 缓冲区
* @param creadlen 读取的偏移量
* @param sout 输出流
* @throws IOException
*/
private void write(byte[] buf, int creadlen, DataOutputStream sout) throws IOException {
sout.write(buf, 0, creadlen);
sout.flush();
}
/**
* 处理HTTPconnect 待定
* @param buf 缓冲区
* @param sreadlen 服务端读取的buf的长度
* @param cin 客户端输入流
* @param sin 服务端输入流
* @param cout 客户端输出流
* @param sout 服务端输出流
* @return
*/
private int doConnect(byte[] buf, int sreadlen, DataInputStream cin, DataInputStream sin, DataOutputStream cout, DataOutputStream sout) {
// 建立线程 , 用于从外网读数据 , 并返回给内网客户端
HTTPChannel thread1 = new HTTPChannel(sin, cout);
try {
while ((sreadlen = cin.read(buf, 0, 10000))!=-1) { // 循环
// 从内网读数据
if (sreadlen > 0) {
// 读到数据 , 则发送给外网
System.out.println("CONN>>" + new String(buf));
write(buf, sreadlen, sout);
}
}
} catch (Exception e1) {
}
return sreadlen;
}
/**
* 处理GET请求
* @param buf 缓冲区
* @param creadlen 客户端读取buf的长度
* @param sin 服务端输入流
* @param cout 客户端输出流
* @param sout 服务端输出流
* @return
* @throws IOException
*/
private int doGet(byte[] buf, int creadlen, DataInputStream sin, DataOutputStream cout, DataOutputStream sout) throws IOException {
int sreadlen;// 如读到 GET 请求，向外网发出 GET 请求
System.out.println("[get] >> " + new String(buf));
write(buf, creadlen, sout);
while ((sreadlen = sin.read(buf, 0, 10000))!=-1) { // 循环
try {
if (sreadlen > 0) {
System.out.println("[get] << " + new String(buf));
write(buf, sreadlen, cout);
}
} catch (Exception e) {
break;
} // 异常则退出
}
return sreadlen;
}
}
再接下来就是上面线程用到的通道类
package com.mato.proxy.http;
import java.io.DataInputStream;
import java.io.DataOutputStream;
/**
* Created by cjl on 2015/9/8.
*/
public class HTTPChannel extends Thread{
private DataInputStream in;
private DataOutputStream out;
public HTTPChannel(DataInputStream sin, DataOutputStream cout) {
in = sin;
out = cout;
start();
}
@Override
public void run() {
int len = 0;
byte buf[] = new byte[10240];
while (true) {
try {
if (len == -1) {
break;
}
if (len > 0) {
System.out.println("post<<"+new String(buf));
out.write(buf, 0, len);
out.flush();
}
} catch (Exception e) {
break;
}
}
}
}
最后就是启动代理服务器的代码
public static void main(String[] args) {
try{
ServerSocket httpserver=new ServerSocket(808);
// 建立 HTTP 侦听套接字
System.out.println ("HTTP Proxy started on "+httpserver.getLocalPort());
HttpProxy httpproxy=new HttpProxy(httpserver); // 建立HTTP 侦听线程
}catch(IOException e){}
}
这样整个HTTP代理服务就构建好了，不过暂时只能代理HTTP请求，不能代理HTTPS
要使用代理服务的话还要在浏览器里面配置代理地址和上面的端口808，过程就不赘述了。可以自行百度。
这是我的火狐浏览器的配置：
最后效果图：
到这里就告一段落了，后面介绍Socket代理服务的实现