JAVA异步的UDP 通讯-服务端

1. 使用NIO实现非阻塞UDP通信

通过DatagramChannel和Selector，可以实现非阻塞的UDP通信，从而高效地处理多个客户端的请求。

示例代码：

java">import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;public class AsyncUDPServer {public static void main(String[] args) throws IOException {DatagramChannel channel = DatagramChannel.open();channel.configureBlocking(false);channel.bind(new InetSocketAddress(9898));Selector selector = Selector.open();channel.register(selector, SelectionKey.OP_READ);while (selector.select() > 0) {for (SelectionKey key : selector.selectedKeys()) {if (key.isReadable()) {ByteBuffer buffer = ByteBuffer.allocate(1024);channel.receive(buffer);buffer.flip();String message = new String(buffer.array(), 0, buffer.limit());System.out.println("Received: " + message);// 可以在此处处理消息并发送响应String response = "Echo: " + message;buffer.clear();buffer.put(response.getBytes());buffer.flip();channel.send(buffer, key.channel().socket().getRemoteSocketAddress());}selector.selectedKeys().remove(key);}}}
}

2. 设置超时和缓冲区大小

为了优化性能，可以设置接收超时时间以及调整接收和发送缓冲区的大小。

示例代码：

java">import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;public class OptimizedUDPServer {public static void main(String[] args) throws Exception {DatagramSocket socket = new DatagramSocket(9898);socket.setSoTimeout(5000); // 设置接收超时时间为5000毫秒socket.setReceiveBufferSize(8192); // 设置接收缓冲区大小socket.setSendBufferSize(8192); // 设置发送缓冲区大小byte[] receiveBuffer = new byte[1024];DatagramPacket receivePacket = new DatagramPacket(receiveBuffer, receiveBuffer.length);while (true) {try {socket.receive(receivePacket);String message = new String(receivePacket.getData(), 0, receivePacket.getLength());System.out.println("Received: " + message);// 发送响应String response = "Echo: " + message;DatagramPacket sendPacket = new DatagramPacket(response.getBytes(), response.getBytes().length,receivePacket.getAddress(), receivePacket.getPort());socket.send(sendPacket);} catch (Exception e) {System.out.println("Error: " + e.getMessage());}}}
}

3. 使用线程池处理请求

通过线程池可以高效地处理多个客户端的请求，避免阻塞主线程。

示例代码：

java">import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;public class ThreadedUDPServer {private static final ExecutorService executor = Executors.newFixedThreadPool(10);public static void main(String[] args) throws Exception {DatagramSocket socket = new DatagramSocket(9898);while (true) {byte[] receiveBuffer = new byte[1024];DatagramPacket receivePacket = new DatagramPacket(receiveBuffer, receiveBuffer.length);socket.receive(receivePacket);executor.submit(() -> {try {String message = new String(receivePacket.getData(), 0, receivePacket.getLength());System.out.println("Received: " + message);// 发送响应String response = "Echo: " + message;DatagramPacket sendPacket = new DatagramPacket(response.getBytes(), response.getBytes().length,receivePacket.getAddress(), receivePacket.getPort());socket.send(sendPacket);} catch (Exception e) {System.out.println("Error: " + e.getMessage());}});}}
}

4. 异步处理和超时机制

在异步处理中，可以设置超时机制，以便在长时间未收到响应时进行处理。

示例代码：

java">import java.net.DatagramSocket;
import java.net.DatagramPacket;
import java.util.concurrent.*;public class AsyncUDPServerWithTimeout {public static void main(String[] args) throws Exception {DatagramSocket socket = new DatagramSocket(9898);ExecutorService executor = Executors.newSingleThreadExecutor();while (true) {byte[] receiveBuffer = new byte[1024];DatagramPacket receivePacket = new DatagramPacket(receiveBuffer, receiveBuffer.length);Future<String> future = executor.submit(() -> {socket.receive(receivePacket);return new String(receivePacket.getData(), 0, receivePacket.getLength());});try {String message = future.get(5, TimeUnit.SECONDS); // 设置超时时间为5秒System.out.println("Received: " + message);// 发送响应String response = "Echo: " + message;DatagramPacket sendPacket = new DatagramPacket(response.getBytes(), response.getBytes().length,receivePacket.getAddress(), receivePacket.getPort());socket.send(sendPacket);} catch (TimeoutException e) {System.out.println("Timeout occurred. No data received within 5 seconds.");}}}
}