1、回显服务器

服务器端

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

public class UDP_Server {
    private DatagramSocket socket=null;
    public UDP_Server(int port) throws SocketException {
        //手动指定端口
        socket=new DatagramSocket(port);
        //系统自动分配端口
        /*socket=new DatagramSocket();*/
    }
    public void start() throws IOException {
        //start方法启动服务器
        System.out.println("服务器启动");
        while (true){
            //1.读取请求
            DatagramPacket requestPacket=new DatagramPacket(new byte[2000],2000);
            socket.receive(requestPacket);
            //receive 后接收到的是二进制，需要转成字符串
            String request=new String(requestPacket.getData(),0,requestPacket.getLength());
            //2.根据请求计算响应,由于这里是回显服务器所以原样子返回
            String response=process(request);
            //3.把响应返回客户端，在DatagramPacket构造在send返回
            DatagramPacket reponsePacket=new DatagramPacket(response.getBytes(), response.getBytes().length,
                    requestPacket.getSocketAddress());
            socket.send(reponsePacket);
            //4.打印日志，交互详情
            System.out.printf("[%s:%d]req:%s,resp=%s\n",requestPacket.getAddress().toString(),requestPacket.getPort(),request,response);
        }
    }

    private String process(String request) {
        return  request;
    }

    public static void main(String[] args) throws IOException {
        UDP_Server udpServer=new UDP_Server(900);
        udpServer.start();
    }
}

客户端

import java.io.IOException;
import java.net.*;
import java.util.Scanner;

public class UDP_Client {
    private DatagramSocket socket=null;
    private String serverIp;
    private int serverPort;
    public UDP_Client(String ip,int port) throws SocketException {
        //创建对象，不能手动指定窗口
        socket=new DatagramSocket();
        //把对端的情况记录下来
        serverIp=ip;
        serverPort=port;
    }
    public void start() throws IOException {
        System.out.println("客户端启动");
        Scanner scanner=new Scanner(System.in);
        while (true){
            //1。从控制台读取数据，作为请求
            System.out.print("->");
            String request=scanner.next();
            //2.把请求内容构造成DatagramPacket对象，发给服务器
            DatagramPacket requestPacket=new DatagramPacket(request.getBytes(),request.getBytes().length,
                    InetAddress.getByName(serverIp),serverPort);
            socket.send(requestPacket);
            //3.读取服务器返回信息
            DatagramPacket responsePacket=new DatagramPacket(new byte[2000],2000);
            socket.receive(responsePacket);
            //4.转换成字符串输出
            String reponse=new String(responsePacket.getData(),0, responsePacket.getLength());
            System.out.println(reponse);
        }
    }

    public static void main(String[] args) throws IOException {
        UDP_Client udpClient=new UDP_Client("127.0.0.1",900);
        udpClient.start();
    }
}

 

 

2、翻译服务器

服务器端

import java.util.Map;

public class UDP_translate_Server extends UDP_Server{
    private Map<String,String> map=new HashMap<>();
    public UDP_translate_Server(int port) throws SocketException {
        super(port);
        map.put("小狗","dog");
        map.put("小猫","cat");
        map.put("小猪","pig");
        map.put("小老鼠","mouse");
    }

    @Override
    public String process(String request) {
        return map.get(request);
    }

    public static void main(String[] args) throws IOException {
        UDP_translate_Server test=new UDP_translate_Server(900);
        test.start();
    }
}

客户端 

import java.io.IOException;
import java.net.*;
import java.util.Scanner;

public class UDP_Client {
    private DatagramSocket socket=null;
    private String serverIp;
    private int serverPort;
    public UDP_Client(String ip,int port) throws SocketException {
        //创建对象，不能手动指定窗口
        socket=new DatagramSocket();
        //把对端的情况记录下来
        serverIp=ip;
        serverPort=port;
    }
    public void start() throws IOException {
        System.out.println("客户端启动");
        Scanner scanner=new Scanner(System.in);
        while (true){
            //1。从控制台读取数据，作为请求
            System.out.print("->");
            String request=scanner.next();
            //2.把请求内容构造成DatagramPacket对象，发给服务器
            DatagramPacket requestPacket=new DatagramPacket(request.getBytes(),request.getBytes().length,
                    InetAddress.getByName(serverIp),serverPort);
            socket.send(requestPacket);
            //3.读取服务器返回信息
            DatagramPacket responsePacket=new DatagramPacket(new byte[2000],2000);
            socket.receive(responsePacket);
            //4.转换成字符串输出
            String reponse=new String(responsePacket.getData(),0, responsePacket.getLength());
            System.out.println(reponse);
        }
    }

    public static void main(String[] args) throws IOException {
        UDP_Client udpClient=new UDP_Client("127.0.0.1",900);
        udpClient.start();
    }
}