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<Device> 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<Device> 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<Device> getDevicesAndClose() {
done = true;
close();
return devices;
}
}
}
