【学习笔记】网络编程之UDP
UDP 发送消息
发送端：
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建立一个DatagramSocket,用来传输
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创建一个数据包 DatagramPacket
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参数：发送的数据、数据的起始长度，要发给谁（ip地址，端口号）
-
-
用send() 方法 发送数据包
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关闭
package com.network.udp;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
public class UdpClientDemo01 {
public static void main(String[] args) throws Exception{
//建立一个Socket
DatagramSocket socket = new DatagramSocket();
//创建一个包
String msg = "你好啊,服务器！";
InetAddress inetAddress = InetAddress.getByName("localhost");
int port = 9090;
DatagramPacket packet = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,inetAddress,port);
//发送包
socket.send(packet);
//关闭
socket.close();
}
}
接收端：
-
开放端口 //DatagramSocket
-
接收数据包
-
需要一个载体，也就是byte数组
-
-
打印发过来的数据
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关闭
package com.network.udp;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
public class UdpServerDemo01 {
public static void main(String[] args) throws Exception{
//开放端口
DatagramSocket socket = new DatagramSocket(9090);
//接收数据包
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);
socket.receive(packet);
//打印
System.out.println(packet.getAddress().getHostAddress());
System.out.println(new String(packet.getData(),0,packet.getLength()));
//关闭
socket.close();
}
}
循环发送和接收
发送方：
-
创建Socket
-
从控制台获取数据
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));-
通过循环发送 包
-
首先读取从控制台获取的数据
String data = reader.readLine(); -
转成 byte 数组类型
-
发送包
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判断是否结束
if(data.equals("bye")){ break; //跳出循环 }
-
-
关闭
完整代码：
package com.network.udp.chat01;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.*;
public class UdpSender01 {
public static void main(String[] args) throws Exception {
//创建Socket
DatagramSocket socket = new DatagramSocket(9999);
//从控制台读取数据
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
while (true){
String data = reader.readLine(); //读取这一行的数据
byte[] datas = data.getBytes();
//发送包
DatagramPacket packet = new DatagramPacket(datas,0,datas.length, new InetSocketAddress("localhost",8888));
socket.send(packet);
if (data.equals("bye")){
break;
}
}
//关闭
reader.close();
socket.close();
}
}
接收端：
-
创建Socket
-
循环接收包
-
准备包的容器 即byte数组
byte[] buffer = new byte[1024]; DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length); -
接收包
-
输出并判断是否要断开
byte[] data = packet.getData(); String receiveData = new String(data,0,packet.getLength()); System.out.println(receiveData); if(receiveData.equals("bye")){ break; }
-
-
关闭
完整代码：
package com.network.udp.chat01;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
public class UdpReceiver01 {
public static void main(String[] args) throws Exception {
DatagramSocket socket = new DatagramSocket(8888);
while (true){
//准备接收包裹
byte[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);
socket.receive(packet);
//断开连接
byte[] data = packet.getData();
String receiveData = new String(data,0, packet.getLength());
System.out.println(receiveData);
if (receiveData.equals("bye")){
break;
}
}
socket.close();
}
}
注意：
在把byte 数组 转化成 字符串时，长度要使用 packet.getLength() ,一定不要使用data.length
因为data.length 的长度为1024
之前是可以使用data.length ，但后来spring版本升级后，集成到packet后就不行了
UDP 多线程实现聊天
线程TalkSend:
package com.network.udp.chap02;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.*;
public class TalkSend implements Runnable{
DatagramSocket socket = null;
BufferedReader reader = null;
private String toIp;
private int toPort;
private int formPort;
public TalkSend(int formPort,String toIp, int toPort) {
this.toIp = toIp;
this.toPort = toPort;
this.formPort = formPort;
try {
socket = new DatagramSocket(formPort);
reader = new BufferedReader(new InputStreamReader(System.in));
} catch (SocketException e) {
e.printStackTrace();
}
}
@Override
public void run() {
while (true){
try {
String data = reader.readLine(); //读取这一行的数据
byte[] datas = data.getBytes();
//发送包
DatagramPacket packet = new DatagramPacket(datas,0,datas.length, new InetSocketAddress(this.toIp,this.toPort));
socket.send(packet);
if (data.equals("bye")){
break;
}
} catch (IOException e) {
e.printStackTrace();
}
}
//关闭
try {
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
socket.close();
}
}
线程TalkReceive:
package com.network.udp.chap02;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;
public class TalkReceive implements Runnable{
DatagramSocket socket = null;
private int port;
private String msgFrom;
public TalkReceive(int port,String msgFrom) {
this.port = port;
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[] buffer = new byte[1024];
DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);
socket.receive(packet);
//断开连接
byte[] data = packet.getData();
String receiveData = new String(data,0, packet.getLength());
System.out.println(msgFrom+"："+receiveData);
if (receiveData.equals("bye")){
break;
}
} catch (IOException e) {
e.printStackTrace();
}
}
socket.close();
}
}
TalkStudent类:
package com.network.udp.chap02;
public class TalkStudent {
public static void main(String[] args) {
//开启两个线程
new Thread(new TalkSend(7777,"localhost",9999)).start();
new Thread(new TalkReceive(8888,"老师")).start();
}
}
TalkTeacher类：
package com.network.udp.chap02;
public class TalkTeacher {
public static void main(String[] args) {
new Thread(new TalkSend(9988,"localhost",8888)).start();
new Thread(new TalkReceive(9999,"学生")).start();
}
}
