proxy.java

一个简单的实现代理服务器的例子。教你如何利用java来实现一个代理服务器

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

/**
 * @author yhy
 * @version 1.0.0
 * The Proxy Server Class
 * 
 */
public class Proxy extends Thread {
	static final int PORT = 8000;

	public static void main(String[] args) throws IOException {
		ServerSocket welcom_socket = new ServerSocket(PORT);
		System.out.println("ThreadedServer has started !\r\n" + welcom_socket);
		try {
			while (true) {
				Socket connect_socket = welcom_socket.accept();
				try {
					new Proxy(connect_socket);
				} catch (IOException e) {
					connect_socket.close();
				}
			}
		} finally {
			welcom_socket.close();
		}
	}

	private Socket socket;

	private BufferedReader in;

	private DataOutputStream out;

	public Proxy(Socket connect_socket) throws IOException {
		socket = connect_socket;
		in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
		out = new DataOutputStream(socket.getOutputStream());
		start();
	}

	public void run() {
		try {
			String command = "";
			String str = in.readLine();
			String uri = "";
			int port = 80;
			System.out.println("Echoing: " + str);

			StringTokenizer tokenizer = new StringTokenizer(str);
			if (tokenizer.hasMoreTokens()
					&& tokenizer.nextToken().equals("GET")) {
				command = tokenizer.nextToken();

				StringTokenizer uritokenizer = new StringTokenizer(command
						.substring(7), "/");
				if (uritokenizer.hasMoreTokens()) {
					uri = uritokenizer.nextToken();
					StringTokenizer porttokenizer = new StringTokenizer(uri,
							":");
					if (porttokenizer.hasMoreTokens()
							&& porttokenizer.countTokens() > 1) {
						uri = porttokenizer.nextToken();
						port = Integer.parseInt(porttokenizer.nextToken());
					}

				} else {
					System.out.println("Bad Command!");
					System.exit(0);
				}
			} else {
				System.out.println("Bad Command!");
				System.exit(0);
			}

			Socket Clientsocket;

			DataInputStream Clientin;

			PrintWriter Clientout;

			BufferedReader inClient;
			DataOutputStream outClient;

			try {
				Clientsocket = new Socket(uri, port);
				if (Clientsocket.isConnected())
					System.out.println(uri
							+ " is listening to your request:\r\n");
				Clientout = new PrintWriter(Clientsocket.getOutputStream(),
						true);
				Clientin = new DataInputStream(Clientsocket.getInputStream());

				Clientout.println(str + "\r\n\r\n");

				System.out.println("\r\nHEADER:\r\n");
				StringTokenizer currenttoken;
				do {
					String currentLine = Clientin.readLine();
					if (currentLine == null) {
						System.out
								.println("Maybe the file doesn't exsit!\r\n"
										+ "Please restart and enter the correct command!");
						System.exit(0);
						//break;
					}
					currenttoken = new StringTokenizer(currentLine);
					System.out.println(currentLine);
					out.writeBytes(currentLine + "\r\n");
				} while (currenttoken.hasMoreTokens());

				String fileName = "index";

				File file = new File(fileName);
				if (file.exists())
					file.delete();

				file.createNewFile();

				RandomAccessFile raf = new RandomAccessFile(file, "rw");

				byte[] buf = new byte[1024];
				int num = Clientin.read(buf, 0, 1024);

				while (num != (-1)) {//是否读完所有数据

					raf.write(buf, 0, num);//将数据写往文件

					raf.skipBytes(num);//顺序写文件字节

					num = Clientin.read(buf);//继续从网络中读取文件

				}
				System.out.println("complete!!!");
				Clientin.close();
				//in.close();

				raf.close();
			} catch (Exception e) {
				System.out.println("failure!!!");
			}

			File file = new File("hao");
			int numOfBytes = (int) file.length();
			FileInputStream inFile = new FileInputStream("hao");

			byte[] fileOutBytes = new byte[numOfBytes];
			inFile.read(fileOutBytes);

			out.write(fileOutBytes, 0, numOfBytes);
		} catch (IOException e) {
			System.out.println(e.toString());
			System.out.println(e.getMessage());
		} finally {
			try {
				socket.close();
			} catch (IOException e) {
			}
		}
	}
}