21.3. UDP Socket

21.3.1. 案例：文件上传工具

UDP_UPloadServer.java

package com.a51work.cn;

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


public class UDP_UploadServer {
    public static void main(String[] args) {
        System.out.println("服务端运行.............");

        // 创建一个子线程
        Thread t = new Thread(() ->{
        try (// 创建一个ServerSocket监听8080端口的客户端请求
             DatagramSocket socket = new DatagramSocket(8080);
             FileOutputStream fout = new FileOutputStream("./hujianli1.sh");
             BufferedOutputStream out = new BufferedOutputStream(fout)) {

            //准备一个缓冲区
            byte[] buffer = new byte[1024];
            while (true) {
                // 创建数据报包对象，用来接收数据
                DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
                // 接收数据报包
                socket.receive(packet);
                // 接收数据长度
                int len = packet.getLength();
                if (len == 3) {
                // 获得结束标志
                    String flag = new String(buffer, 0, 3);
                    // 判断结束标志，如果是bye结束接收
                    if (flag.equals("bye")) {
                        break;
                    }
            }
                // 写入数据到文件输出流
                out.write(buffer, 0, len);
            }
            System.out.println("接收完成！");
        } catch (IOException e) {
            e.printStackTrace();
        }
        });

        //启动线程
        t.start();
    }
}

UDP_UPloadClient.java

package com.a51work.cn;

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

public class UDP_UploadClient {
    public static void main(String[] args) {
        System.out.println("客户端运行............");
        try (// 创建DatagramSocket对象，由系统分配可以使用的端口
             DatagramSocket socket = new DatagramSocket();
             FileInputStream fin = new FileInputStream("D:\\GitHub\\test.sh");
             BufferedInputStream in = new BufferedInputStream(fin)) {

            // 创建远程主机IP地址对象
            InetAddress address = InetAddress.getByName("localhost");

            // 准备一个缓冲区
            byte[] buffer = new byte[1024];
            // 首次从文件流中读取数据
            int len = in.read(buffer);
            while (len != -1) {
                // 创建数据报包对象
                DatagramPacket packet = new DatagramPacket(buffer, len, address, 8080);
                // 发送数据表
                socket.send(packet);
                //再次从文件流中读取数据
                len = in.read(buffer);
            }
            // 创建数据报对象
            DatagramPacket packet = new DatagramPacket("bye".getBytes(), 3, address, 8080);
            // 发送结束标志
            socket.send(packet);
            System.out.println("上传完成！");
            } catch(IOException e){
                e.printStackTrace();
            }
        }
    }

21.3.2. 案例：聊天工具

UDP_ChatServer.java

package com.a51work.cn;

import java.io.*;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.Socket;

public class UDP_ChatServer {
    public static void main(String[] args) {
        System.out.println("服务器运行...............");
        // 创建一个子线程
        Thread t = new Thread(() -> {
            try (// 创建DatagramSocket对象，指定端口8080
                 DatagramSocket socket = new DatagramSocket(8080);
                 BufferedReader keyboardIn
                         = new BufferedReader(new InputStreamReader(System.in))) {
                while (true) {
                    /* 接收数据 */
                    //准备一个缓冲区
                    byte[] buffer = new byte[128];
                    DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
                    socket.receive(packet);

                    // 接收数据长度
                    int len = packet.getLength();

                    String str = new String(buffer, 0, len);

                    // 打印接收的数据
                    System.out.printf("从客户端接收的数据：【%s】\n", str);

                    /* 发送数据 */
                    // 从客户端传来的数据包中得到客户端地址
                    InetAddress address = packet.getAddress();
                    // 从客户端传来的数据包中得到客户端端口号
                    int port = packet.getPort();

                    // 读取键盘输入的字符串
                    String keyboardInputString = keyboardIn.readLine();
                    // 读取键盘输入的字节数组
                    byte[] b = keyboardInputString.getBytes();
                    // 创建DatagramPacket对象，用于向客户端发送数据
                    packet = new DatagramPacket(b, b.length, address, port);
                    // 向客户端发送数据
                    socket.send(packet);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        });

        //启动线程
        t.start();

    }
}

UDP_ChatClient.java

package com.a51work.cn;

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

public class UDP_ChatClient {
    public static void main(String[] args) {
        System.out.println("客户端运行...............");
        // 创建一个子线程
        Thread t = new Thread(() -> {
            try (// 创建DatagramSocket对象，指定端口8080
                 DatagramSocket socket = new DatagramSocket();
                 BufferedReader keyboardIn
                         = new BufferedReader(new InputStreamReader(System.in))) {
                while (true) {
                    /* 接收数据 */
                    //准备一个缓冲区
                    byte[] buffer = new byte[128];
                    // 服务器IP地址
                    InetAddress address = InetAddress.getByName("localhost");
                    // 服务器端口号
                    int port = 8080;
                    // 读取键盘输入的字符串
                    String keyboardInputString = keyboardIn.readLine();

                    if (keyboardInputString.equals("bye")) {
                        break;
                    }
                    // 读取键盘输入的字节数组
                    byte[] b = keyboardInputString.getBytes();

                    // 创建DatagramPacket对象，用于向客户端发送数据
                    DatagramPacket packet = new DatagramPacket(b, b.length, address, port);
                    // 发送
                    socket.send(packet);

                    // 接收数据包
                    packet = new DatagramPacket(buffer, buffer.length);
                    socket.receive(packet);

                    // 接收数据长度
                    int len = packet.getLength();
                    String str = new String(buffer, 0, len);
                    // 打印接收的数据
                    System.out.printf("从服务器接收的数据：【%s】\n", str);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        });

        //启动线程
        t.start();

    }
}