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Java基于ServletContextListener實現(xiàn)UDP監(jiān)聽

更新時間：2019年12月05日 09:56:53 作者：遺失的拂曉

這篇文章主要介紹了Java基于ServletContextListener實現(xiàn)UDP監(jiān)聽,文中通過示例代碼介紹的非常詳細，對大家的學習或者工作具有一定的參考學習價值,需要的朋友可以參考下

使用spring boot實現(xiàn)項目啟動時的監(jiān)聽，

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;

@WebListener
public 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 {
　　　　　　　// 啟動一個線程，監(jiān)聽UDP數(shù)據(jù)報
      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，然后解碼
      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掃描，啟動時把servlet、filter、listener自動掃描注入

UDP測試客戶端（也可以用測試工具發(fā)送UDP包測試）：

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";
  // 服務(wù)器端口
  public static final int SERVER_PORT = 26666;
  // 本地發(fā)送端口
  public static final int LOCAL_PORT = 8888;

  public static void main(String[] args) {
    try {
      // 1，創(chuàng)建udp服務(wù)。通過DatagramSocket對象。
      DatagramSocket socket = new DatagramSocket(LOCAL_PORT);
      // 2，確定數(shù)據(jù)，并封裝成數(shù)據(jù)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，通過socket服務(wù)，將已有的數(shù)據(jù)包發(fā)送出去。通過send方法。
      socket.send(dp);
      // 4，關(guān)閉資源。
      socket.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

}

結(jié)果：