[网络协议]JavaSE进阶--网络编程(3)--UDP与URL

UDP

UDP消息发送

发送端

package com.Sucker.lesson03;

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

//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.建包
        String msg = "你好啊，服务器";

        //发送给谁
        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;
        //数据，数据的长度起始，要发送给谁
        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，没有也可以发送

package com.Sucker.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
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);

        socket.receive(packet);//阻塞接收

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

        socket.close();

    }

}

循环发送消息

发送端

package com.Sucker.chat;

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

public class UdpSenderDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(8888);

        //准备数据，控制台读取System.in
        //InputStreamReader为桥转换流，将字节流转换为字符流，BufferedReader字符缓冲流
        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));

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

        socket.close();

    }

}

接收端

package com.Sucker.chat;

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

public class UdpReceiveDemo01 {
    public static void main(String[] args) throws Exception {
        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);
            socket.receive(packet);//阻塞式接收包裹

            //断开连接 bye
            byte[] data = packet.getData();
            String datas = new String(data,0, data.length);

            System.out.println(datas.trim());

            if(datas.trim().equals("bye")) break;//trim方法删除头尾空白字符串

        }

        socket.close();
    }

}

在线咨询，双方都可以是发送方和接收方

发送端工具类

package com.Sucker.chat;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
import java.util.concurrent.ExecutionException;

public class TalkSend implements Runnable{
    DatagramSocket socket = null;
    BufferedReader reader = null;

    private int fromPort;
    private String toIP;
    private int toProt;

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

        try {
            socket = new DatagramSocket(fromPort);
            reader = new BufferedReader(new InputStreamReader(System.in));
        }catch (Exception e){
            e.printStackTrace();
        }


    }

    @Override
    public void run() {
        while(true){
            try{
                String data = reader.readLine();
                byte[] datas = data.getBytes();
                DatagramPacket packet = new DatagramPacket(datas,0,datas.length,new InetSocketAddress(this.toIP,this.toProt));

                socket.send(packet);
                if(data.equals("bye")) break;
            }catch (Exception e){
                e.printStackTrace();
            }

        }
        socket.close();
    }
}

接收端工具类

package com.Sucker.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.port = port;
        this.msgFrom=msgFrom;
        try {
            socket = new DatagramSocket(port);//开启连接
        } 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);
                socket.receive(packet);//阻塞式接收包裹

                //断开连接 bye
                byte[] data = packet.getData();
                String datas = new String(data,0, data.length);

                System.out.println(msgFrom+":"+datas.trim());

                if(datas.trim().equals("bye")) break;//trim方法删除头尾空白字符串
            } catch (IOException e) {
                e.printStackTrace();
            }

        }

        socket.close();
    }
}

学生

package com.Sucker.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();
    }

}

老师

package com.Sucker.chat;

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();
    }

}

URL

URL：统一资源定位符：定位资源的，定位互联网上的某一个资源

DNS域名解析：www.baidu.com xxx.x…x

协议：//ip地址：端口/项目名/资源

package com.Sucker.lesson04;

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

public class URLDown {
    public static void main(String[] args) throws Exception {
        //1.下载地址
        URL url = new URL("https://tse3-mm.cn.bing.net/th/id/OIP-C.UJn6UIedh0fIZk5V4f_5zgHaE8?w=256&h=180&c=7&o=5&pid=1.7");

        //2.连接到这个资源 HTTP
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

        InputStream inputStream = urlConnection.getInputStream();

        FileOutputStream fos = new FileOutputStream("111.jpg");

        byte[] buffer = new byte[1024];
        int len;
        while ((len=inputStream.read(buffer))!=-1){
            fos.write(buffer,0,len);//写出数据
        }

        fos.close();
        inputStream.close();
        urlConnection.disconnect();//断开连接

    }

}