【Socket网络编程进阶与实战】------- Socket UDP快速入门
前言
Socket UDP快速入门，demo实战
UDP
为什么不可靠
能做什么
UDP包最大长度
核心API
API-DatagramSocket
API-DatagramPacket
UDP 单播、广播、多播
- IP地址类别
- 广播地址
- 广播地址运算
- 广播通信问题
案例实操-局域网搜索案例
- UDP接收消息并回送功能实现
- UDP局域网广播发送实现
- UDP局域网回送消息实现
package com.zcw.demo;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
/**
* @ClassName : UDPProvider
* @Description :UDP提供者，用于提供服务
* @Author : Zhaocunwei
* @Date: 2020-07-07 14:09
*/
public class UDPProvider {
public static void main(String[] args) throws IOException {
System.out.println("UDPProvider Started.");
//作为接收者，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 winth len:"+dataLen;
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(),
receivePack.getPort());
ds.send(responsePacket);
//完成
System.out.println("UDPProvider Finished.");
ds.close();
}
}
package com.zcw.demo;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
/**
* @ClassName : UDPSearcher
* @Description : UDP 搜索，用于搜索服务支持方
* @Author : Zhaocunwei
* @Date: 2020-07-07 14:09
*/
public class UDPSearcher {
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();
//构建一份回送数据
String requestData = "HelloWord:";
byte[] requestDataBytes = requestData.getBytes();
//直接根据发送者构建一份回送信息
DatagramPacket requestPacket = new DatagramPacket(requestDataBytes,
requestDataBytes.length);
//本机端口20000
requestPacket.setAddress(InetAddress.getLocalHost());
requestPacket.setPort(20000);
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();
}
}
- 测试：
优化上面Demo
- 创建消息创建者
package com.zcw.demo;
/**
* @ClassName : MessageCreator
* @Description :发送消息
* @Author : Zhaocunwei
* @Date: 2020-07-07 14:44
*/
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;
}
}
- 修改内容提供者
package com.zcw.demo;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
import java.util.UUID;
/**
* @ClassName : UDPProvider
* @Description :UDP提供者，用于提供服务
* @Author : Zhaocunwei
* @Date: 2020-07-07 14:09
*/
public class UDPProvider {
public static void main(String[] args) throws IOException {
//生成一份唯一标识
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
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 {
//构造一个监听
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;
}
}
/**
* 提供结束方法
*/
void exit() {
done = true;
close();
}
}
}
- 修改我们的数据搜索者
package com.zcw.demo;
import java.io.IOException;
import java.net.*;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.CountDownLatch;
/**
* @ClassName : UDPSearcher
* @Description : UDP 搜索，用于搜索服务支持方
* @Author : Zhaocunwei
* @Date: 2020-07-07 14:09
*/
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 listen = listen();
sendBroadcast();
//读取任意键盘信息后可以退出
System.in.read();
List<Device> devices = listen.getDevicesAndClose();
for (Device device :devices){
System.out.println("Device:"+device.toString());
}
//完成
System.out.println("UDPSearcher Finished.");
}
private static Listener listen() throws InterruptedException {
System.out.println("UDPSearcher start listen.");
CountDownLatch countDownLatch = new CountDownLatch(1);
Listener listener = new Listener(LISTEN_PORT,countDownLatch);
listener.start();
countDownLatch.await();
return listener;
}
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();
//构建一份回送数据
String requestData = MessageCreator.buildWithPort(LISTEN_PORT);
byte[] requestDataBytes = requestData.getBytes();
//直接根据发送者构建一份回送信息
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);
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 + '\'' +
'}';
}
}
/**
* 实现监听类
*/
private static class Listener extends Thread{
private final int listenPort;
private final CountDownLatch countDownLatch;
private final List<Device> devices = new ArrayList<Device>();
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;
}
}
}
- 测试：
