Java Socket编程实例（一）- TCP基本使用

一.服务端代码：

import java.net.*; // for Socket, ServerSocket, and InetAddress
import java.io.*; // for IOException and Input/OutputStream

public class TCPEchoServer {

  private static final int BUFSIZE = 32; // Size of receive buffer

  public static void main(String[] args) throws IOException {

    int servPort = 5500;

    // Create a server socket to accept client connection requests
    ServerSocket servSock = new ServerSocket(servPort);

    int recvMsgSize; // Size of received message
    byte[] receiveBuf = new byte[BUFSIZE]; // Receive buffer

    while (true) { // Run forever, accepting and servicing connections
      Socket clntSock = servSock.accept(); // Get client connection

      SocketAddress clientAddress = clntSock.getRemoteSocketAddress();
      System.out.println("Handling client at " + clientAddress);

      InputStream in = clntSock.getInputStream();
      OutputStream out = clntSock.getOutputStream();

      // Receive until client closes connection, indicated by -1 return
      while ((recvMsgSize = in.read(receiveBuf)) != -1) {
        out.write(receiveBuf, 0, recvMsgSize);
      }

      clntSock.close(); // Close the socket. We are done with this client!
    }
    /* NOT REACHED */
  }
}

二.客户端代码：

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

public class TCPEchoClient {

  public static void main(String[] args) throws IOException {

    String server = "127.0.0.1"; // Server name or IP address
    int servPort = 5500; //// Server port
    byte[] data = "Hi, World".getBytes();

    // Create socket that is connected to server on specified port
    Socket socket = new Socket(server, servPort);
    System.out.println("Connected to server...sending echo string");

    InputStream in = socket.getInputStream();
    OutputStream out = socket.getOutputStream();

    out.write(data); // Send the encoded string to the server

    // Receive the same string back from the server
    int totalBytesRcvd = 0; // Total bytes received so far
    int bytesRcvd; // Bytes received in last read
    while (totalBytesRcvd < data.length) {
      if ((bytesRcvd = in.read(data, totalBytesRcvd, data.length - totalBytesRcvd)) == -1)
        throw new SocketException("Connection closed prematurely");
      totalBytesRcvd += bytesRcvd;
    } // data array is full

    System.out.println("Received: " + new String(data));
    socket.close(); // Close the socket and its streams
  }
}

上述代码的TCP服务端是单线程，一次只能服务一个客户端。

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