java网络编程--4 UDP

1.7、UDP

发短信：不用连接，但是需要知道对方的地址

主要包含两个类：DatagramPacket 和 DatagramSocket

发送消息

发送端：

package com.ssl.lesson03;

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

//不需要连接服务器
public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception{
        //1.建立一个Socket
        DatagramSocket socket = new DatagramSocket();

        //2.建个包
        String msg = "你好";
        //发送给谁
        InetAddress localhost = InetAddress.getByName("127.0.0.1");
        int port = 9090;
        //数据，数据的长度起始，长度，ip，端口号
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length,localhost,port);
        //3.发送包
        socket.send(packet);

        //4.关闭流
        socket.close();
    }
}

接收端：

package com.ssl.lesson03;

import java.net.DatagramPacket;
import java.net.DatagramSocket;

//还是要等待客户端的连接
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);

        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(),0,packet.getLength()));

        //关闭连接
        socket.close();
    }
}

咨询

发送方：

package com.ssl.chat;

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{
        //设定UDP的端口号
        DatagramSocket socket = 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 data = reader.readLine();
            byte[] datas = data.getBytes();

            DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress("localhost",6666));
            //发送数据
            socket.send(packet);
            if(data.equals("bye"))
                break;
        }


        socket.close();
    }
}

//接收方

package com.ssl.chat;

import java.net.DatagramPacket;
import java.net.DatagramSocket;

public class UdpReceiveDemo01 {
    public static void main(String[] args) throws Exception{
        //设定UDP端口号,接收端口
        DatagramSocket socket = new DatagramSocket(6666);
        while(true){

            //准备接收包裹
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container,0,container.length);

            //接收包裹
            socket.receive(packet);

            //断开连接 bye
            byte[] data = packet.getData();
            //将接收的信息生成字符串。
            String receiveData = new String(data, 0, packet.getLength());
            System.out.println(receiveData);
            if(receiveData.equals("bye")){
                break;
            }
        }
        socket.close();
    }
}

在线咨询

双方可以相互通信

package com.ssl.chat;

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

//发送线程
public class TalkSend implements  Runnable{
    DatagramSocket socket = null;
    BufferedReader reader = null;

    //对方的端口号
    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 {
            //设定UDP的端口号
            socket = new DatagramSocket(fromPort);
            //准备数据：控制台读取System.in
            reader = new BufferedReader(new InputStreamReader(System.in));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


    @Override
    public void run() {
        //发送消息
        while(true){
            try {
                String data = reader.readLine();
                byte[] datas = data.getBytes();

                DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress(this.toIP,this.toPort));
                //发送数据
                socket.send(packet);
                if(data.equals("bye")){
                    break;
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

package com.ssl.chat;

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.msgFrom= msgFrom;
        this.port = port;
        //接收端口
        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);
                //接收包裹
                socket.receive(packet);
                //断开连接 bye
                byte[] data = packet.getData();
                //将接收的信息生成字符串。
                String receiveData = new String(data, 0, packet.getLength());
                System.out.println(this.msgFrom+":"+receiveData);
                if(receiveData.equals("bye")){
                    break;
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

package com.ssl.chat;

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();

    }
}

package com.ssl.chat;

public class TalkTeacher {
    public static void main(String[] args) {
        //开启两个线程  一个接收，一个发送
        new Thread(new TalkSend(5555,"localhost",8888)).start();
        new Thread(new TalkReceive(9999,"学生")).start();

    }
}