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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