需求:应用A(通常有多个)和应用B(1个)进行 socket通讯,应用A必须知道应用B的ip地址(在应用A的配置文件中写死的),这个时候就必须把应用B的ip设成固定ip(但是某些时候如更换路由后要重新设置网络,但是操作人员不知道这个规则),就有可能造成应用A和应用B无法进行正常通讯,所以要改成应用A动态获取应用B的ip地址。
经过讨论决定采用udp协议实现,upd是一种无连接的传输层协议。应用A在不知道应用B的 ip情况下 可以使用广播地址255.255.255.255,将消息发送到在同一广播网络上的B。从而获取B的ip。
实现代码:
B应用为服务端:将udp监听放到一个线程中,当有客户端请求时就会进行响应
- /**
- * udp连接,用于动态ip, pos向255.255.255.255:5060发送请求即可
- * **/
- public class UdpServer extends Thread implements Runnable {
- private final int MAX_LENGTH = 1024;
- private final int PORT = 5060;
- private DatagramSocket datagramSocket;
-
- public void run() {
- try {
- init();
- while(true){
- try {
- byte[] buffer = new byte[MAX_LENGTH];
- DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
- receive(packet);
- String receStr = new String(packet.getData(), 0 , packet.getLength());
- System.out.println("接收数据包" + receStr);
- byte[] bt = new byte[packet.getLength()];
-
- System.arraycopy(packet.getData(), 0, bt, 0, packet.getLength());
- System.out.println(packet.getAddress().getHostAddress() + ":" + packet.getPort() + ":" + Arrays.toString(bt));
- packet.setData(bt);
- response(packet);
-
- } catch (Exception e) {
- e.printStackTrace();
- LoggerUtil.error("udp线程出现异常:" + e.toString());
- }
- }
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
-
- public void receive(DatagramPacket packet) throws Exception {
- datagramSocket.receive(packet);
- }
-
- public void response(DatagramPacket packet) throws Exception {
- datagramSocket.send(packet);
- }
-
- /**
- * 初始化连接
- */
- public void init(){
- try {
- datagramSocket = new DatagramSocket(PORT);
- System.out.println("udp服务端已经启动!");
- } catch (Exception e) {
- datagramSocket = null;
- System.out.println("udp服务端启动失败!");
- e.printStackTrace();
- }
- }
- }
-
客户端:本来客户端是使用pb来实现的,但是这里使用java来模拟
- /***
- * UDP Client端
- ***/
- public class UdpClient {
-
- private String sendStr = "hello";
- private String netAddress = "255.255.255.255";
- private final int PORT = 5060;
-
- private DatagramSocket datagramSocket;
- private DatagramPacket datagramPacket;
-
- public UdpClient(){
- try {
- datagramSocket = new DatagramSocket();
- byte[] buf = sendStr.getBytes();
- InetAddress address = InetAddress.getByName(netAddress);
- datagramPacket = new DatagramPacket(buf, buf.length, address, PORT);
- datagramSocket.send(datagramPacket);
-
- byte[] receBuf = new byte[1024];
- DatagramPacket recePacket = new DatagramPacket(receBuf, receBuf.length);
- datagramSocket.receive(recePacket);
-
- String receStr = new String(recePacket.getData(), 0 , recePacket.getLength());
-
- //获取服务端ip
- String serverIp = recePacket.getAdress();
- } catch (SocketException e) {
- e.printStackTrace();
- } catch (UnknownHostException e) {
- e.printStackTrace();
- } catch (IOException e) {
- e.printStackTrace();
- } finally {
- // 关闭socket
- if(datagramSocket != null){
- datagramSocket.close();
- }
- }
- }
-
- public static void main(String[] args) {
- for (int i = 0; i < 100; i++) {
- new Thread(new Runnable() {
- @Override
- public void run() {
- UdpClient udpClient = new UdpClient();
- }
- }).start();
- }
- }
- }
以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持w3xue。