Java学习笔记--网络编程--练习在线咨询

接收方

import java.net.DatagramPacket;
import java.net.DatagramSocket;
//在线咨询的雏形
public class UdpReceiveDemo01 {
public static void main(String[] args) throws Exception {
DatagramSocket datagramSocket = new DatagramSocket(6666);
while (true) {
//准备接收包裹
byte[] buffer = new byte[1024];
DatagramPacket datagramPacket = new DatagramPacket(buffer,0,buffer.length);

datagramSocket.receive(datagramPacket);//阻塞式接受包裹

//断开链接
byte[] data=datagramPacket.getData();
String sdata=new String(data,0,datagramPacket.getLength());//注意 这里不能用data的长度，因为字节数组长度以及固定，即便输入了bye下面的equals也不会停止

System.out.println(sdata);

if (sdata.equals("bye")){
break;
}
}
datagramSocket.close();
}
}

发送方

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

public class UdpSenderDemo01 {
public static void main(String[] args) throws Exception {

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 s = reader.readLine();
byte[] data=s.getBytes();
DatagramPacket datagramPacket = new DatagramPacket(data,0,data.length,new InetSocketAddress("localhost",6666));

datagramSocket.send(datagramPacket);
if (s.equals("bye")){
break;
}
}

datagramSocket.close();
}
}

多线程改进：
发送线程：

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;

public class TalkSend implements Runnable{
/*
多线程改进   发送线程
*/
BufferedReader reader =null;
DatagramSocket socket =null;
private int fromPort;
private String toIP;
private int toPort;

public TalkSend(int fromPort, String toIP, int toPort) {
this.fromPort = fromPort;
this.toIP = toIP;
this.toPort = toPort;

try{
socket=new DatagramSocket(fromPort);
reader = new BufferedReader(new InputStreamReader(System.in));

}catch (Exception e){
e.printStackTrace();
}
}

@Override
public void run() {
//准备数据：控制台读取System.in

while (true){
try{
String s = reader.readLine();
byte[] data=s.getBytes();
DatagramPacket datagramPacket = new DatagramPacket(data,0,data.length,new InetSocketAddress(this.toIP,this.toPort));
socket.send(datagramPacket);
if (s.equals("bye")){
break;
}
}catch (Exception e){
e.printStackTrace();
}
}
socket.close();
}
}

接收线程：

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class TalkReceive implements Runnable{
/*
多线程改进   接收线程
*/
DatagramSocket datagramSocket =null;
private int port;
private String msgFrom;

public TalkReceive(int port,String msgFrom) {
this.port = port;
this.msgFrom=msgFrom;
try {
datagramSocket =new DatagramSocket(port);
} catch (SocketException e) {
e.printStackTrace();
}
}

@Override
public void run() {
while (true) {
//准备接收包裹
try {
byte[] buffer = new byte[1024];
DatagramPacket datagramPacket = new DatagramPacket(buffer,0,buffer.length);

datagramSocket.receive(datagramPacket);//阻塞式接受包裹

//断开链接
byte[] data=datagramPacket.getData();
String sdata=new String(data,0,datagramPacket.getLength());//注意 这里不能用data的长度，因为字节数组长度以及固定，即便输入了bye下面的equals也不会停止

System.out.println(msgFrom+"："+sdata);

if (sdata.equals("bye")){
break;
}
} catch (IOException e) {
e.printStackTrace();
}
}
datagramSocket.close();
}
}

实际应用：
老师方：

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

学生方：

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();
}
}