服務器端

package httpProxyServer;

import java.io.InputStream;
import java.io.OutputStream;
import java.net.ServerSocket;
import java.net.Socket;

public class HttpServer {

    public static void main(String[] args) {
        // test，我們先用helloWorld測試一下
        int port;// 定義服務器需要綁定的本地端口號
        ServerSocket serverSocket;// 定義服務器套接口對象

        // 不得不吐槽這異常拋的真不正規
        try {
            port = Integer.getInteger(args[1]);// 將第二個命令行參數轉化為整數
        } catch (Exception e) {
            System.out.println("port = 8888 (默認)");
            port = 8888;
        }

        try {
            serverSocket = new ServerSocket(port);
            System.out.println("服務器正在監聽端口：" + serverSocket.getLocalPort());

            while (true) {
                try {
                    final Socket socket = serverSocket.accept();
                    System.out.println("建立了與客戶的新的TCP連接，該客戶的地址為：" + socket.getInetAddress() + ":" + socket.getPort());
                    service(socket);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static void service(Socket socket) throws Exception {
        // 讀取http請求信息
        InputStream socketIn = socket.getInputStream();// 創建輸入流通道
        Thread.sleep(500);
        int size = socketIn.available();// 獲取輸入流中緩存的大小
        byte[] buffer = new byte[size];// 根據緩存大小在緩存外面建立緩存buffer
        socketIn.read(buffer);// 讀取緩存信息到buffer中
        String request = new String(buffer);// 將緩存buffer中的字節放到字符串中
        System.out.println(request);// 輸出字符串

        // 解析http請求信息
        String firstLineOfRequest = request.substring(0, request.indexOf("\n\r"));
        String[] parts = firstLineOfRequest.split(" ");
        String uri = parts[1];

        // 決定http響應的正文類型
        String contentType;
        if (uri.indexOf("html") != -1 || uri.indexOf("htm") != -1)
            contentType="text/html";
        else if(uri.indexOf("jpg") != -1 || uri.indexOf("jpeg") != -1)
            contentType="image/jpeg";
        else if(uri.indexOf("gif") != -1)
            contentType="image/gif";
        else
            contentType="application/octet-stream";
        
        //創建http響應結果
        String responseFirstLine = "HTTP/1.1 200 OK\r\n";
        String responseHeader = "Content-type:" + contentType + "\r\n\r\n";
        InputStream in = HttpServer.class.getResourceAsStream("root/" + uri);//讀取指定位置的文件到輸入流,這邊需要注意的是路徑，/代表是項目目錄，沒有代表當前類所在的目錄
        OutputStream socketout = socket.getOutputStream();//獲得套接字的輸出流
        socketout.write(responseFirstLine.getBytes());//向套接字輸出流中寫入響應頭
        socketout.write(responseHeader.getBytes());//向套接字輸出流中寫入首部項
        int len = 0;
        buffer = new byte[128];
        while((len = in.read(buffer))!=-1){
            socketout.write(buffer,0,len);//從文件輸入流中循環讀取字符到套接字輸出流中
        }
        
        //關閉套接字
        Thread.sleep(1000);
        socket.close();
    }
}

客戶端：

package httpProxyServer;

import java.io.InputStream;
import java.io.OutputStream;
import java.net.Socket;

public class HttpClient {

    public static void main(String[] args) {
        String uri = "index.html";
        if(args.length != 0) uri=args[0];//這邊需要區別c語言下的參數，這邊的第一個參數是不包括命令行自身的。
        doGet("localhost",8888,uri);
    }

    private static void doGet(String host, int port, String uri) {
        Socket socket = null;
        try {
            socket = new Socket(host,port);
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        try {
            //創建http請求
            StringBuffer sb = new StringBuffer("GET " + uri + " HTTP/1.1\r\n");
            sb.append("Accept: */*\r\n");
            sb.append("Accept-Encoding: gzip,deflate\r\n");
            sb.append("Accept-Language: zh-cn\r\n");
            sb.append("User-Agent: HTTPClient\r\n");
            sb.append("Connection: Keep-Alive\r\n\r\n");
            
            //發送http請求
            OutputStream socketOut = socket.getOutputStream();
            socketOut.write(sb.toString().getBytes());
            Thread.sleep(2000);
            
            //接收響應結果
            InputStream socketIn = socket.getInputStream();
            int size = socketIn.available();
            byte[] buffer = new byte[size];
            socketIn.read(buffer);
            System.out.println(new String(buffer));
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                socket.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}