import java.net.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
public class UDPServer {
private static final int PORT = 9876;
private static final int BUFFER_SIZE = 1024;
private static final int THREAD_POOL_SIZE = 10;
public static void main(String[] args) {
ExecutorService threadPool = Executors.newFixedThreadPool(THREAD_POOL_SIZE);
try (DatagramSocket serverSocket = new DatagramSocket(PORT)) {
System.out.println("UDP Server started on port " + PORT);
while (true) {
byte[] receiveData = new byte[BUFFER_SIZE];
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
serverSocket.receive(receivePacket);
threadPool.execute(new ClientHandler(serverSocket, receivePacket));
}
} catch (Exception e) {
e.printStackTrace();
} finally {
threadPool.shutdown();
}
}
static class ClientHandler implements Runnable {
private final DatagramSocket socket;
private final DatagramPacket packet;
public ClientHandler(DatagramSocket socket, DatagramPacket packet) {
this.socket = socket;
this.packet = packet;
}
@Override
public void run() {
try {
String message = new String(packet.getData(), 0, packet.getLength());
System.out.println("Received from " + packet.getAddress() + ":" + packet.getPort() + " - " + message);
String response = "ECHO: " + message;
byte[] sendData = response.getBytes();
DatagramPacket sendPacket = new DatagramPacket(
sendData, sendData.length, packet.getAddress(), packet.getPort());
socket.send(sendPacket);
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
import java.net.*;
import java.util.Scanner;
public class UDPClient {
private static final String SERVER_IP = "127.0.0.1";
private static final int SERVER_PORT = 9876;
private static final int TIMEOUT_MS = 3000;
public static void main(String[] args) {
try (DatagramSocket clientSocket = new DatagramSocket();
Scanner scanner = new Scanner(System.in)) {
clientSocket.setSoTimeout(TIMEOUT_MS);
InetAddress serverAddress = InetAddress.getByName(SERVER_IP);
while (true) {
System.out.print("Enter message (type 'exit' to quit): ");
String message = scanner.nextLine();
if ("exit".equalsIgnoreCase(message)) break;
byte[] sendData = message.getBytes();
DatagramPacket sendPacket = new DatagramPacket(
sendData, sendData.length, serverAddress, SERVER_PORT);
clientSocket.send(sendPacket);
byte[] receiveData = new byte[1024];
DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
try {
clientSocket.receive(receivePacket);
String response = new String(receivePacket.getData(), 0, receivePacket.getLength());
System.out.println("Server response: " + response);
} catch (SocketTimeoutException e) {
System.out.println("Request timed out");
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
服务端采用线程池处理并发请求，每个客户端请求由独立线程处理
客户端实现超时重试机制，3秒内未收到响应显示超时提示
项目配置为Maven工程，支持直接通过exec-maven-plugin运行
服务端实现简单的ECHO功能，将客户端消息原样返回并添加前缀
客户端支持交互式输入，输入exit可安全退出程序