UDP(User Datagram Protocol) 用户数据报协议
发短信：不用连接，只需要知道对方的地址即可。
示例：
UDPClient.java
package net;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
// 不需要连接服务器
public class UDPClient {
public static void main(String[] args) throws IOException {
// 1.建立一个Socket
DatagramSocket datagramSocket = new DatagramSocket();
// 2.建个包
String msg = "Hello server.";
// 发送给谁
InetAddress localhost = InetAddress.getByName("localhost");
int port = 9090;
// 数据,数据长度起始,要发送给谁
DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);
// 3.发送包
datagramSocket.send(packet);
// 4.关闭流
datagramSocket.close();
}
}
UDPServer.java
package net;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
// 还是要等待用户端的连接
public class UDPServer {
public static void main(String[] args) throws IOException {
// 开放端口
DatagramSocket datagramSocket = new DatagramSocket(9090);
// 接收数据
byte[] buffer = new byte[1024];
DatagramPacket datagramPacket = new DatagramPacket(buffer, 0, buffer.length);// 接收
datagramSocket.receive(datagramPacket);// 阻塞接收
System.out.println(datagramPacket.getAddress());
System.out.println(new String(datagramPacket.getData(), 0, datagramPacket.getLength()));
// 关闭连接
datagramSocket.close();
}
}
运行结果：
UDP实现聊天
UDPSender.java
package net.chat;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
public class UDPSender {
public static void main(String[] args) throws IOException {
DatagramSocket datagramSocket = new DatagramSocket(8888);
// 准备数据: 控制台读取 System.in
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
while (true) {
String msg = reader.readLine();
byte[] msgBytes = msg.getBytes();
DatagramPacket packet = new DatagramPacket(msgBytes, 0, msgBytes.length, new InetSocketAddress("localhost", 6666));
datagramSocket.send(packet);
if (msg.equals("Bye")) {
break;
}
}
datagramSocket.close();
}
}
UDPReceive.java
package net.chat;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class UDPReceive {
public static void main(String[] args) throws IOException {
DatagramSocket datagramSocket = new DatagramSocket(6666);
while (true) {
// 准备接收包裹
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container, 0, container.length);
datagramSocket.receive(packet);// 阻塞式接收包裹
// 断开连接
byte[] data = packet.getData();
String receiveData = new String(data, 0, data.length);
System.out.println(receiveData);
if (receiveData.trim().equals("Bye")) {
break;
}
}
datagramSocket.close();
return;
}
}
运行结果：
UDP多线程在线咨询
TalkSend.java
package net.chat;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;
public class TalkSend implements Runnable {
DatagramSocket datagramSocket = null;
BufferedReader reader = null;
private int fromPort;
private String toIp;
private int toPort;
public TalkSend(int fromPort, String toIp, int toPort) throws SocketException {
this.fromPort = fromPort;
this.toIp = toIp;
this.toPort = toPort;
datagramSocket = new DatagramSocket(fromPort);
reader = new BufferedReader(new InputStreamReader(System.in));
}
@Override
public void run() {
try {
while (true) {
String msg = reader.readLine();
byte[] msgBytes = msg.getBytes();
DatagramPacket packet = new DatagramPacket(msgBytes, 0, msgBytes.length, new InetSocketAddress(toIp, toPort));
datagramSocket.send(packet);
if (msg.equals("Bye")) {
break;
}
}
} catch (Exception e) {
e.printStackTrace();
}
datagramSocket.close();
}
}
TalkReceive.java
package net.chat;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
public class TalkReceive implements Runnable {
DatagramSocket datagramSocket = null;
private int port;
private String msgFrom;
public TalkReceive(int port, String msgFrom) throws SocketException {
this.port = port;
this.msgFrom = msgFrom;
datagramSocket = new DatagramSocket(port);
}
public static void main(String[] args) {
}
@Override
public void run() {
while (true) {
// 准备接收包裹
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container, 0, container.length);
try {
datagramSocket.receive(packet);// 阻塞式接收包裹
} catch (IOException e) {
e.printStackTrace();
}
// 断开连接
byte[] data = packet.getData();
String receiveData = new String(data, 0, data.length);
System.out.println(msgFrom + ": " + receiveData);
if (receiveData.trim().equals("Bye")) {
break;
}
}
datagramSocket.close();
return;
}
}
TalkStudent.java
package net.chat;
import java.net.SocketException;
public class TalkStudent {
public static void main(String[] args) throws SocketException {
// 开启2个线程
new Thread(new TalkSend(7777, "localhost", 9999)).start();
new Thread(new TalkReceive(8888, "老师")).start();
}
}
TalkTeacher.java
package net.chat;
import java.net.SocketException;
public class TalkTeacher {
public static void main(String[] args) throws SocketException {
// 开启2个线程
new Thread(new TalkSend(5555, "localhost", 8888)).start();
new Thread(new TalkReceive(9999, "学生")).start();
}
}
运行结果：
