JAVA-UDP

JAVA-UDP

public static void main(String[] args) throws IOException { System.out.println("UDPSearcher Started."); //作为搜索方，让系统自动分配端口 DatagramSocket ds=new DatagramSocket(); //构建一份请求数据 String requestData="HelloWord"; byte[] requestDataBytes=requestData.getBytes(); //直接构建packet DatagramPacket requestPacket=new DatagramPacket(requestDataBytes, requestDataBytes.length); //本机2000端口 requestPacket.setAddress(InetAddress.getLocalHost()); requestPacket.setPort(2000); //发送 ds.send(requestPacket); //构建接收实体 final byte[] buf=new byte[512]; DatagramPacket receivePack=new DatagramPacket(buf,buf.length); //接收 ds.receive(receivePack); //打印接收到的信息与发送者的信息 //发送者的ip地址 String ip=receivePack.getAddress().getHostAddress(); int port=receivePack.getPort(); int dataLen=receivePack.getLength(); String data=new String(receivePack.getData(),0,dataLen); System.out.println("UDPSearcher receive form ip:"+ip +"\tport:"+port+"\tdata:"+ data); //完成 System.out.println("UDPSearcher Finished."); ds.close(); }

public static void main(String[] args) throws IOException { System.out.println("UDPProvider Started."); //作为接受者，指定一个端口用于数据接收 DatagramSocket ds=new DatagramSocket(20000); //构建接收实体 final byte[] buf=new byte[512]; DatagramPacket receivePack=new DatagramPacket(buf,buf.length); //接收 ds.receive(receivePack); //打印接收到的信息与发送者的信息 //发送者的ip地址 String ip=receivePack.getAddress().getHostAddress(); int port=receivePack.getPort(); int dataLen=receivePack.getLength(); String data=new String(receivePack.getData(),0,dataLen); System.out.println("UDPProvider receive form ip:"+ip +"\tport:"+port+"\tdata:"+ data); //构建一份回送数据 String responseData="Receive data with len:"+dataLen; byte[] responseDataBytes=responseData.getBytes(); //直接根据回送者构建一份回送信息 DatagramPacket responsePacket=new DatagramPacket(responseDataBytes, responseDataBytes.length, receivePack.getAddress(), receivePack.getPort()); ds.send(responsePacket); //完成 System.out.println("UDPProvider Finished."); ds.close();}

广播局域网搜索功能：

public class MessageCreator { private static final String SN_HEADER = "收到暗号，我是（SN）:"; private static final String PORT_HEADER = "这是暗号，请回电端口（Port）:"; public static String buildWithPort(int port) { return PORT_HEADER + port; } public static int parsePort(String data) { if (data.startsWith(PORT_HEADER)) { return Integer.parseInt(data.substring(PORT_HEADER.length())); } return -1; } public static String buildWithSn(String sn) { return SN_HEADER + sn; } public static String parseSn(String data) { if (data.startsWith(SN_HEADER)) { return data.substring(SN_HEADER.length()); } return null; }}

import java.io.IOException;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.util.UUID;public class UDPProvider { public static void main(String[] args) throws IOException { // 生成一份唯一标示 String sn = UUID.randomUUID().toString(); Provider provider = new Provider(sn); provider.start(); // 读取任意键盘信息后可以退出 //noinspection ResultOfMethodCallIgnored System.in.read(); provider.exit(); } private static class Provider extends Thread { private final String sn; private boolean done = false; private DatagramSocket ds = null; public Provider(String sn) { super(); this.sn = sn; } @Override public void run() { super.run(); System.out.println("UDPProvider Started."); try { // 监听20000 端口 ds = new DatagramSocket(20000); while (!done) { // 构建接收实体 final byte[] buf = new byte[512]; DatagramPacket receivePack = new DatagramPacket(buf, buf.length); // 接收 ds.receive(receivePack); // 打印接收到的信息与发送者的信息 // 发送者的IP地址 String ip = receivePack.getAddress().getHostAddress(); int port = receivePack.getPort(); int dataLen = receivePack.getLength(); String data = new String(receivePack.getData(), 0, dataLen); System.out.println("UDPProvider receive form ip:" + ip + "\tport:" + port + "\tdata:" + data); // 解析端口号 int responsePort = MessageCreator.parsePort(data); if (responsePort != -1) { // 构建一份回送数据 String responseData = MessageCreator.buildWithSn(sn); byte[] responseDataBytes = responseData.getBytes(); // 直接根据发送者构建一份回送信息 DatagramPacket responsePacket = new DatagramPacket(responseDataBytes, responseDataBytes.length, receivePack.getAddress(), responsePort); ds.send(responsePacket); } } } catch (Exception ignored) { } finally { close(); } // 完成 System.out.println("UDPProvider Finished."); } private void close() { if (ds != null) { ds.close(); ds = null; } } /** * 提供结束 */ void exit() { done = true; close(); } }}

import java.io.IOException;import java.net.*;import java.util.ArrayList;import java.util.List;import java.util.concurrent.CountDownLatch;//搜索者，用于搜搜服务支持方public class UDPSearcher { private static final int LISTEN_PORT = 30000; public static void main(String[] args) throws IOException ,InterruptedException{ System.out.println("UDPSearcher Started."); Listener listener = listen(); sendBroadcast(); // 读取任意键盘信息后可以退出 //noinspection ResultOfMethodCallIgnored System.in.read(); List devices = listener.getDevicesAndClose(); for (Device device : devices) { System.out.println("Device:" + device.toString()); } // 完成 System.out.println("UDPSearcher Finished."); } //监听方法 private static Listener listen() throws InterruptedException{ System.out.println("UDPSeacher start listen."); CountDownLatch countDownLatch=new CountDownLatch(1); Listener listener=new Listener(LISTEN_PORT,countDownLatch); listener.start(); countDownLatch.wait(); return listener; } //发送广播 private static void sendBroadcast() throws IOException { System.out.println("UDPSearcher sendBroadcast started."); // 作为搜索方，让系统自动分配端口 DatagramSocket ds = new DatagramSocket(); // 构建一份请求数据 String requestData = MessageCreator.buildWithPort(LISTEN_PORT); byte[] requestDataBytes = requestData.getBytes(); // 直接构建packet DatagramPacket requestPacket = new DatagramPacket(requestDataBytes, requestDataBytes.length); // 20000端口, 广播地址 requestPacket.setAddress(InetAddress.getByName("255.255.255.255")); requestPacket.setPort(20000); // 发送 ds.send(requestPacket); ds.close(); // 完成 System.out.println("UDPSearcher sendBroadcast finished."); } private static class Device{ final int port; final String ip; final String sn; private Device(int port, String ip, String sn) { this.port = port; this.ip = ip; this.sn = sn; } @Override public String toString() { return "Device{" + "port=" + port + ", ip='" + ip + '\'' + ", sn='" + sn + '\'' + '}'; } } private static class Listener extends Thread{ private final int listenPort; private final CountDownLatch countDownLatch; private final List devices = new ArrayList<>(); private boolean done = false; private DatagramSocket ds = null; public Listener(int listenPort,CountDownLatch countDownLatch){ super(); this.listenPort = listenPort; this.countDownLatch = countDownLatch; } @Override public void run(){ super.run(); // 通知已启动 countDownLatch.countDown(); try { // 监听回送端口 ds = new DatagramSocket(listenPort); while (!done) { // 构建接收实体 final byte[] buf = new byte[512]; DatagramPacket receivePack = new DatagramPacket(buf, buf.length); // 接收 ds.receive(receivePack); // 打印接收到的信息与发送者的信息 // 发送者的IP地址 String ip = receivePack.getAddress().getHostAddress(); int port = receivePack.getPort(); int dataLen = receivePack.getLength(); String data = new String(receivePack.getData(), 0, dataLen); System.out.println("UDPSearcher receive form ip:" + ip + "\tport:" + port + "\tdata:" + data); String sn = MessageCreator.parseSn(data); if (sn != null) { Device device = new Device(port, ip, sn); devices.add(device); } } } catch (Exception ignored) { } finally { close(); } System.out.println("UDPSearcher listener finished."); } private void close() { if (ds != null) { ds.close(); ds = null; } } List getDevicesAndClose() { done = true; close(); return devices; } }}

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