Java学习笔记52(网络编程:UDP协议案例)

InetAddress类:表示互联网中的IP地址,示例:
package demo;

import java.net.InetAddress;
import java.net.UnknownHostException;

public class InetAddressDemo {
    public static void main(String[] args) throws UnknownHostException {
        function1();
        function2();
    }

    public static void function1() throws UnknownHostException {
        InetAddress inet = InetAddress.getLocalHost();
        System.out.println(inet.getHostName());// 获取主机名
        // 输出:DESKTOP-Q3O8AEO
        System.out.println(inet.getHostAddress());// 获取主机IP
        // 输出:192.168.87.1
    }

    public static void function2() throws UnknownHostException {
        // 获得其他IP
        InetAddress inet = InetAddress.getByName("www.baidu.com");
        System.out.println(inet);
        // 输出:www.baidu.com/111.13.100.92
    }
}
View Code UDP协议:无连接通信协议,最大64KB,不安全TCP协议:面向连接通信协议,可靠安全,三次握手以确认连接,相对速度慢,适合大数据传输 UDP示例:发送端:
package demo;

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

public class UDPSend {
    public static void main(String[] args) {
        try {
            byte[] data = "你好".getBytes();
            InetAddress inet = InetAddress.getByName("127.0.0.1");
            DatagramPacket dp = new DatagramPacket(data, data.length, inet, 6000);
            DatagramSocket ds = new DatagramSocket();
            ds.send(dp);
            ds.close();
        } catch (IOException ex) {
            System.out.println(ex);
        }
    }
}
View Code 接收端:
package demo;

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

public class UDPReceive {
    public static void main(String[] args) {
        try {
            DatagramSocket ds = new DatagramSocket(6000);
            byte[] data = new byte[1024];
            DatagramPacket dp = new DatagramPacket(data, data.length);
            ds.receive(dp);
            int length = dp.getLength();
            String ip = dp.getAddress().getHostAddress();
            System.out.println(ip + ":" + new String(data, 0, length));
            ds.close();
        } catch (IOException ex) {
            System.out.println(ex);
        }
    }
}
View Code先运行接收端,再运行发送端,结果:输出:127.0.0.1:你好 功能可以提升,实现键盘输入的聊天:发送端:
package demo;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.util.Scanner;

public class UDPSend {
    public static void main(String[] args) {
        try {
            Scanner sc = new Scanner(System.in);
            DatagramSocket ds = new DatagramSocket();
            InetAddress inet = InetAddress.getByName("127.0.0.1");
            while (true) {
                String message = sc.nextLine();
                byte[] data = message.getBytes();
                DatagramPacket dp = new DatagramPacket(data, data.length, inet, 7000);
                ds.send(dp);
            }
        } catch (IOException ex) {
            System.out.println(ex);
        }
    }
}
View Code接收端:
package demo;

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

public class UDPReceive {
    public static void main(String[] args) {
        try {
            DatagramSocket ds = new DatagramSocket(7000);
            byte[] data = new byte[1024];
            while (true) {
                DatagramPacket dp = new DatagramPacket(data, data.length);
                ds.receive(dp);
                int length = dp.getLength();
                String ip = dp.getAddress().getHostAddress();
                System.out.println(ip + ":" + new String(data, 0, length));
            }
        } catch (IOException ex) {
            System.out.println(ex);
        }
    }
}
View Code 先后运行,在发送端发送的消息可以随时在接收端收到,这里就实现了一个简单的聊天功能同个局域网下的多台电脑之间也可以聊天,只要修改成相应的IP地址即可 

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