目录

UDP网络编程

说明

练习一

发送方

接收方

练习二：在线咨询

客户端

服务端

发送端多线程

接收端多线程

学生端

老师端

UDP网络编程

说明

• DatagramSocket 和 DatagramPacket 两个类实现了基于UDP协议的网络程序。
• UDP 数据报通过数据报套接字 DatagramSocket 发送和接收，系统不保证UDP数据报一定能够安全送到目的地，也不确定什么时候可以抵达。
• DatagramPacket 对象封装了UDP数据报，在数据报中包含了发送端的IP地址和端口号以及接收端的IP地址和端口号。
• UDP协议中每个数据报都给出了完整的地址信息，因此无需建立发送方和接收方的连接。如同发快递包裹一样

练习一

发送方

package com.kou.lesson5;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
public class UDPSenderDemo01 {
public static void main(String[] args) throws Exception {
//1. 建立DatagramSocket
DatagramSocket socket = new DatagramSocket();
//2. 封装数据包
String msg = "UDPSender==>";
byte[] data = msg.getBytes();
InetAddress inet = InetAddress.getByName("127.0.0.1");
int port = 9090;
DatagramPacket packet = new
DatagramPacket(data,0,data.length,inet,port);
//3. 通过 Socket 发送 packet
socket.send(packet);
//4. 关闭socket
socket.close();
}
}
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接收方

package com.kou.lesson5;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class UDPReceiverDemo01 {
public static void main(String[] args) throws Exception {
//1. 建立DatagramSocket,开放端口
DatagramSocket socket = new DatagramSocket(9090);
//2. 接收数据
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);
socket.receive(packet);
//3. 输出数据
// packet.getData() : 获取packet中的数据
System.out.println(new String(packet.getData(), 0,
packet.getLength()));
//4. 关闭socket
socket.close();
}
}

启动接收方，启动发送方，能够接收到！

练习二：在线咨询

客户端

package com.kou.udpchat;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
public class UdpTalkClient {
public static void main(String[] args) throws Exception {
System.out.println("发送方启动中....");
//1. 使用DatagramSocket 指定端口，创建发送端
DatagramSocket socket = new DatagramSocket(8888);
//2. 准备数据，转成字节数组
BufferedReader reader = new BufferedReader(newInputStreamReader(System.in));
while (true){
String data = reader.readLine();
byte[] datas = data.getBytes();
//3. 封装成DatagramPacket包裹，需要指定目的地
DatagramPacket packet = new DatagramPacket(datas,0,datas.length,
new InetSocketAddress("localhost",6666));
//4. 发送包裹send
socket.send(packet);
//退出判断
if (data.equals("bye")){
break;
}
}
//5. 释放资源
socket.close();
}
}
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服务端

package com.kou.udpchat;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class UdpTalkServer {
public static void main(String[] args) throws Exception {
DatagramSocket socket = new DatagramSocket(6666);
while (true) {
try {
//准备接收包裹；
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container, 0,container.length);
socket.receive(packet); //阻塞式接收包裹
byte[] datas = packet.getData();
int len = packet.getLength();
String data = new String(datas,0,len);
System.out.println(data);
//退出判断
if (data.equals("bye")){
break;
}
}catch (Exception e){
e.printStackTrace();
}
}
socket.close();
}
}
点击并拖拽以移动

现在需要两遍需要接受和发送，我们可以使用多线程来解决！

发送端多线程

package com.kou.udpchat;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.net.SocketException;
//发送端
public class TalkSend implements Runnable {
private DatagramSocket socket;
private BufferedReader reader;
private String toIP;
private int toPort;
public TalkSend(int port,String toIP,int toPort) {
this.toIP = toIP;
this.toPort = toPort;
try {
socket = new DatagramSocket(port);
reader = new BufferedReader(new InputStreamReader(System.in));
} catch (SocketException e) {
e.printStackTrace();
}
}
@Override
public void run() {
while (true){
try {
String data = reader.readLine();
byte[] datas = data.getBytes();
//3. 封装成DatagramPacket包裹，需要指定目的地
DatagramPacket packet = new
DatagramPacket(datas,0,datas.length,
new InetSocketAddress(this.toIP,this.toPort));
//4. 发送包裹send
socket.send(packet);
//退出判断
if (data.equals("bye")){
break;
}
}catch (Exception e){
e.printStackTrace();
}
}
//5. 释放资源
socket.close();
}
}
点击并拖拽以移动

接收端多线程

package com.kou.udpchat;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
//接收端
public class TalkReceive implements Runnable {
private DatagramSocket socket;
private String msgFrom;
public TalkReceive(int port,String msgFrom) {
this.msgFrom = msgFrom;
try {
socket = new DatagramSocket(port);
} catch (SocketException e) {
e.printStackTrace();
}
}
@Override
public void run() {
while (true) {
try {
//准备接收包裹；
byte[] container = new byte[1024];
DatagramPacket packet = new DatagramPacket(container, 0,
container.length);
socket.receive(packet); //阻塞式接收包裹
byte[] datas = packet.getData();
int len = packet.getLength();
String data = new String(datas,0,len);
System.out.println(msgFrom+":"+data);
//退出判断
if (data.equals("bye")){
break;
}
}catch (Exception e){
e.printStackTrace();
}
}
socket.close();
}
}

学生端

package com.kou.udpchat;
public class TalkStudent {
public static void main(String[] args) {
new Thread(new TalkSend(7777,"localhost",9999)).start();
new Thread(new TalkReceive(8888,"老师")).start();
}
}

老师端

package com.kou.udpchat;
public class TalkTeacher {
public static void main(String[] args) {
new Thread(new TalkReceive(9999,"学生")).start();
new Thread(new TalkSend(5555,"localhost",8888)).start();
}
}