【JavaNET】Java网路编程(4)

前言：

本文内容：UDP聊天实现、UDP多线程在线咨询、UDP下载网络资源

推荐免费Java网络编程实战讲解视频：【狂神说Java】网络编程实战讲解_哔哩哔哩_bilibili

Java网络编程(NET)笔记代码下载地址：

蓝奏云：下载地址 密码：joker

百度云：下载地址 提取码：jpvx

UDP聊天实现

循环发送消息：

package com.jokerdig.chat;

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

/**
 * @author Joker大雄
 * @data 2021/9/4 - 10:37
 **/
public class UdpSenderDemo01 {
    public static void main(String[] args) throws IOException {
        DatagramSocket socket = new DatagramSocket(8888);

        //准备数据，控制台读取 System.in
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        //循环发送
        while(true){
            String data=reader.readLine();

            byte[] bytes = data.getBytes();
            DatagramPacket packet = new DatagramPacket(bytes,0,bytes.length,new InetSocketAddress("localhost",6666));

            socket.send(packet);
            if(data.equals("bye")){
                break;
            }
        }
    }
}

循环接收消息：

package com.jokerdig.chat;

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

/**
 * @author Joker大雄
 * @data 2021/9/4 - 10:37
 **/
public class UdpServerDemo01 {
    public static void main(String[] args) throws IOException{
        DatagramSocket socket = new DatagramSocket(6666);

        while (true){
            //准备接收包裹
            byte[] bytes = new byte[1024];
            DatagramPacket packet = new DatagramPacket(bytes,0,bytes.length);
            socket.receive(packet);
            //断开
            byte[] data = packet.getData();
            String s = new String(data,0, packet.getLength());//packet.length()会无法停止
            System.out.println(s);
            if(s.equals("bye")){
                break;
            }
        }
        socket.close();//释放资源
    }
}

UDP多线程在线咨询

在线咨询：

两个人都可以是发送方，也都可以是接收方。

发送端：

package com.jokerdig.chat;

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

/**
 * @author Joker大雄
 * @data 2021/9/4 - 12:49
 **/
public class TalkSeed implements Runnable{

    DatagramSocket socket=null;
    BufferedReader reader=null;
    private int fromPort;
    private String toIp;
    private int toPort;
    //构造器
    public TalkSeed(int fromPort, String toIp, int toPort) {
        this.fromPort = fromPort;
        this.toIp = toIp;
        this.toPort = toPort;
        try {
            socket = new DatagramSocket(fromPort);
            //准备数据，控制台读取 System.in
            reader = new BufferedReader(new InputStreamReader(System.in));
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {
        //循环发送
        while(true){
            String data= null;
            try {
                data = reader.readLine();
                byte[] bytes = data.getBytes();
                DatagramPacket packet = new DatagramPacket(bytes,0,bytes.length,new InetSocketAddress(this.toIp,this.toPort));
                socket.send(packet);

                if(data.equals("bye")){
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

接收端：

package com.jokerdig.chat;

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

/**
 * @author Joker大雄
 * @data 2021/9/4 - 13:23
 **/
public class TalkReceive implements Runnable{
    DatagramSocket socket=null;
    DatagramPacket packet=null;
    private int port;
    private String fromMsg;

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

    @Override
    public void run() {

        while (true){
            //准备接收包裹
            try {
                byte[] bytes = new byte[1024];
                packet = new DatagramPacket(bytes,0,bytes.length);
                socket.receive(packet);
                //断开
                byte[] data = packet.getData();
                String s = new String(data,0, packet.getLength());//packet.length()会无法停止
                System.out.println(fromMsg+"发送："+s);
                if(s.equals("bye")){
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        socket.close();//释放资源
    }
}

用户：

package com.jokerdig.chat;

/**
 * @author Joker大雄
 * @data 2021/9/4 - 13:35
 **/
//用户
public class TalkUser {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSeed(7777,"localhost",9999)).start();
        new Thread(new TalkReceive(8888,"客户")).start();
    }
}

客户：

package com.jokerdig.chat;

/**
 * @author Joker大雄
 * @data 2021/9/4 - 13:36
 **/
//客户
public class TalkClient {
    public static void main(String[] args) {
        new Thread(new TalkSeed(6666,"localhost",8888)).start();
        new Thread(new TalkReceive(9999,"用户")).start();
    }
}

UDP下载网络资源

URL：统一资源定位符，定位互联网某一资源。

DNS域名解析：www.jokerdig.com

---

协议：//ip地址：端口/项目名/资源

URL方法：

package com.jokerdig.url;

import java.net.MalformedURLException;
import java.net.URL;

/**
 * @author Joker大雄
 * @data 2021/9/4 - 13:56
 **/
public class UrlDemo {
    public static void main(String[] args) throws MalformedURLException {
      URL url=  new URL("https://localhost:8080/helloword/index.jsp?username=name&password=123");
        System.out.println(url.getProtocol());//协议
        System.out.println(url.getHost());//主机ip
        System.out.println(url.getPort());//端口
        System.out.println(url.getPath());//文件
        System.out.println(url.getFile());//全路径
        System.out.println(url.getQuery());//参数
    }
}

URL文件下载：

package com.jokerdig.url;

import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

/**
 * @author Joker大雄
 * @data 2021/9/4 - 14:05
 **/
public class UrlFileDownload {
    public static void main(String[] args) throws Exception{
      //下载地址
      URL url = new URL("https://jokerdig.com/images/avatar.png");
      //连接资源
      HttpURLConnection http=(HttpURLConnection) url.openConnection();
        InputStream inputStream = http.getInputStream();
        FileOutputStream file = new FileOutputStream("avatar.png");

        byte[] buffer = new byte[1024];
        int len;
        while((len=inputStream.read(buffer))!=-1){
            file.write(buffer,0,len);//写出数据
        }
        //释放资源
        file.close();
        inputStream.close();
        http.disconnect();//断开
    }
}