这篇文章主要介绍了Java基于ServletContextListener实现UDP监听,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下
使用spring boot实现项目启动时的监听，
UDPListener
import java.io.IOException;import java.io.UnsupportedEncodingException;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.SocketException;import javax.servlet.ServletContextEvent;import javax.servlet.ServletContextListener;import javax.servlet.annotation.WebListener;
@WebListenerpublic class UDPListener implements ServletContextListener { public static final int MAX_UDP_DATA_SIZE = 4096; public static final int UDP_PORT = 26666; @Override public void contextInitialized(ServletContextEvent sce) { System.out.println("========UDPListener Initialized========="); try { // 启动一个线程，监听UDP数据报 new Thread(new UDPProcess(UDP_PORT)).start(); } catch (Exception e) { e.printStackTrace(); } } class UDPProcess implements Runnable { DatagramSocket socket = null; public UDPProcess(final int port) throws SocketException { socket = new DatagramSocket(port); } @Override public void run() { // TODO Auto-generated method stub System.out.println("=======UDPProcess======"); while (true) { byte[] buffer = new byte[MAX_UDP_DATA_SIZE]; DatagramPacket packet = new DatagramPacket(buffer, buffer.length); try { socket.receive(packet); new Thread(new Process(packet)).start(); } catch (IOException e) { e.printStackTrace(); } } } } class Process implements Runnable { public Process(DatagramPacket packet) throws UnsupportedEncodingException { // TODO Auto-generated constructor stub byte[] buffer = packet.getData();// 接收到的UDP信息，然后解码 String srt1 = new String(buffer,"GBK").trim(); String srt2 = new String(buffer, "UTF-8").trim(); String srt3 = new String(buffer,"ISO-8859-1").trim(); System.out.println("=======Process srt1 GBK======" + srt1); System.out.println("=======Process srt2 UTF-8======" + srt2); System.out.println("=======Process srt3 ISO-8859-1======" + srt3); } @Override public void run() { // TODO Auto-generated method stub System.out.println("====Process run====="); } } @Override public void contextDestroyed(ServletContextEvent sce) { System.out.println("========UDPListener Destroyed========="); }}
DemoApplication
@SpringBootApplication@ServletComponentScan public class DemoApplication { public static void main(String[] args) { SpringApplication.run(DemoApplication.class, args); }}
@ServletComponentScan Servlet扫描，启动时把servlet、filter、listener自动扫描注入
UDP测试客户端（也可以用测试工具发送UDP包测试）：
import java.io.IOException;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.net.InetAddress;
public class UDPClientTest { public static final String SERVER_HOSTNAME = "localhost"; // 服务器端口 public static final int SERVER_PORT = 26666; // 本地发送端口 public static final int LOCAL_PORT = 8888; public static void main(String[] args) { try { // 1，创建udp服务。通过DatagramSocket对象。 DatagramSocket socket = new DatagramSocket(LOCAL_PORT); // 2，确定数据，并封装成数据包。DatagramPacket(byte[] buf, int length, InetAddress // address, int port) byte[] buf = "你好，世界".getBytes(); DatagramPacket dp = new DatagramPacket(buf, buf.length, InetAddress.getByName(SERVER_HOSTNAME), SERVER_PORT); // 3，通过socket服务，将已有的数据包发送出去。通过send方法。 socket.send(dp); // 4，关闭资源。 socket.close(); } catch (IOException e) { e.printStackTrace(); } }}
结果：
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本文标题: Java基于ServletContextListener实现UDP监听
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