JAVA SOCKET 编程——TCP/UDP

import java.io.*;import java.net.Socket;import java.util.Scanner;public class Client {    public static void main(String[] args) throws IOException {        Socket socket = new Socket("127.0.0.1", 9898);        Scanner console = new Scanner(System.in);        System.out.print("请输入请求>");        String request = console.nextLine();        OutputStream os = socket.getOutputStream();        PrintWriter writer = new PrintWriter(new OutputStreamWriter(os, "UTF-8"));        writer.println(request);        writer.flush();        InputStream is = socket.getInputStream();        Scanner scanner = new Scanner(is, "UTF-8");        String response = scanner.nextLine();   //对象没有响应，就一直等        System.out.println(response);        socket.close();    }}

import java.io.*;import java.net.ServerSocket;import java.net.Socket;import java.util.Scanner;import java.util.concurrent.ExecutorService;import java.util.concurrent.Executors;
public class Server {    private static class ServiceMan extends Thread {        private final Socket socket;
        ServiceMan(Socket socket) {            this.socket = socket;        }
        @Override        public void run() {            try {                //获取输入流                InputStream is = socket.getInputStream();                //封装成Scanner                Scanner scanner = new Scanner(is, "UTF-8");                //使用\r\n进行分割的方式，读取请求
                //等着第一个Client发送请求                String request = scanner.nextLine();//nextLine把\r\n已经去掉了                System.out.println("收到请求:" + request);
                //业务处理                String response = request;
                //发送响应，也需要使用\r\n跟在后面，进行分割                OutputStream os = socket.getOutputStream();//得到输出流                //封装成PrintWriter                PrintWriter writer = new PrintWriter(                        new OutputStreamWriter(os, "UTF-8")                );                //发送响应                writer.println(response);//println会帮我们在后面加\r\n                writer.flush();                writer.close();            } catch (IOException e) {                e.printStackTrace();            }        }    }
    public static void main(String[] args) throws IOException {        //开店        ServerSocket serverSocket = new ServerSocket(9898);        ExecutorService threadPool = Executors.newFixedThreadPool(20);        //循环处理任务        //主线程只负责接待客人——建立连接的过程        while (true) {                        /*            Socket socket = serverSocket.accept();            //所有业务处理的过程，交给工作线程去处理            new ServiceMan(socket).start();            */                        //更好的做法，引进线程池            //各个线程之间，没有数据共享（主线程和工作线程共享socket）            //所以天生是线程安全的            Socket socket = serverSocket.accept();            threadPool.execute(new ServiceMan(socket));        }    }}

1、创建server的socket2、循环读取请求(request)，解析并处理请求，生成响应(response)3、发送响应
提供给Server一些简单的功能。version1：回显服务。发送给服务端什么，就把这个消息发送回去。version2：翻译服务。输入英文，返回对应的意思和例句。version3：轮盘聊天。多个客户端，其中一个客户端发送消息到服务端，服务端随机将这个消息返回给某一个客户端。1234567891011

import java.io.IOException;import java.net.DatagramPacket;import java.net.DatagramSocket;import java.util.*;
public class Server {//服务端
    public static void main(String[] args) throws IOException {              //1.创建server的socket  类似于开饭店              // 内部会进行本地ip+port的绑定              // 例子：饭店开张，提供一个大家都认识的地段 ip + port              // ip虽然没传，但内部会帮我们处理，把所有的ip都会绑定        try (DatagramSocket socket = new DatagramSocket(9939)) {            //2.开门迎客，通过循环，处理业务            while (true) {            //3.处理一个要求并返回响应                action(socket);            }        }    }    /**     * 处理要求     */    private static void action(DatagramSocket socket) throws IOException {        //1.读取客户端发来的请求            //1.1准备一个字节数组，用来存放一会儿要读到的数据        byte[] receiveBuffer = new byte[8192];            //1.2把buffer封装成datagram        DatagramPacket receivePacket = new DatagramPacket(receiveBuffer, 0, 8192);           //1.3读取请求        socket.receive(receivePacket);            //1.4从receive中返回，就意味着，有人给我发送请求了            //需要将byte[]中的数据进行 字符集编码->String        String request = new String(receiveBuffer, 0, receivePacket.getLength(), "UTF-8");        System.out.printf("收到的请求是|%s|%n", request);//收到请求
        //2.进行服务---根据请求,处理业务，并生成响应            //Version1:回显服务——echo服务            //客户端发送什么过来，就发送回去什么            //String response=request;                        //Version2：字典查询服务——请求是英文，响应是中文+例句 有道查询            String response = translate(request);
            //Version3：轮盘聊天——给我发送过请求的ip+port，我会记录下来，            // 然后再有人给我发送来新的请求时，随机选择一个ip+port发送回去            //不保证对方还在线，所以不保证对方能收到            //randomTalk(socket,request, receivePacket.getAddress(), receivePacket.getPort());
        //3.发送响应回去            //Version1、2对应的发送响应代码块        byte[] sendBuffer = response.getBytes("UTF-8");        DatagramPacket sendPacket = new DatagramPacket(sendBuffer, 0,                sendBuffer.length,                receivePacket.getAddress(),                receivePacket.getPort());        socket.send(sendPacket);
    }        /*Version3对应的发送响应代码块    private static class Remote {//Remote用来保存客户端的ip+port        private InetAddress address;        private int port;
        private Remote(InetAddress address, int port) {            this.address = address;            this.port = port;        }    }
    //所有曾经给我发消息的客户端的信息——远端    private static List<Remote> remoteList = new ArrayList<>();    private static Random random = new Random();
    private static void randomTalk(DatagramSocket socket,String request, InetAddress address, int port) throws IOException {
        System.out.printf("之前已经有%s个客户端发送了消息%n",remoteList.size());        if(remoteList.size()>0) {        //随机一个下标，决定吧这个消息发给他        int rIndex = random.nextInt(remoteList.size());        Remote remote = remoteList.get(rIndex);            System.out.printf("决定发送给%s客户端%n",rIndex);
        //发送消息        byte[] sendBuffer = request.getBytes("UTF-8");        DatagramPacket sendPacket = new DatagramPacket(sendBuffer, 0,                sendBuffer.length,                remote.address,                remote.port        );        socket.send(sendPacket);    }        //发送完毕将自己加入remoteList中        remoteList.add(new Remote(address,port));    }    */        //Version2用到的内部类和一些静态代码块、方法    private static class Result {//字典        String chinese;//中文字段        String sentence;//英文字段        private Result(String chinese, String sentence) {            this.chinese = chinese;            this.sentence = sentence;        }    }
    private static Map<String, Result> dictionary = new TreeMap<>();//用来存放字典中的元素    //静态代码块，用于初始化静态属性    static {        dictionary.put("dictionary", new Result("字典", "He threw my dictionary back."));        dictionary.put("mask", new Result("口罩", "They contrived a mask again"));    }
    private static String translate(String english) {        //按最简单的翻译功能实现——提前保存一份字典        Result result = dictionary.get(english);        if (result == null) {            return "不支持的单词.";        }        return String.format("%s%n%s%n", result.chinese, result.sentence);    }}

循环{1、读取用户输入2、封装成请求并发送3、读取并解析响应4、把结果返回给用户}

import java.io.IOException;import java.net.*;import java.util.Scanner;public class Client {//客户端    public static void main(String[] args) throws IOException {        Scanner scanner = new Scanner(System.in);        try (DatagramSocket socket = new DatagramSocket()) {            while (true) {                //读取用户输入                System.out.print("随便输入什么然后回车>");                String str = scanner.nextLine();                //发送请求                byte[] sendBuffer = str.getBytes("UTF-8");                DatagramPacket sendPacket = new DatagramPacket(                        sendBuffer, 0, sendBuffer.length,                        InetAddress.getByName("127.0.0.1"), 9939                );                socket.send(sendPacket);//完成发送                //接收响应的过程                byte[] receiveBuffer = new byte[8192];                DatagramPacket receivePacket = new DatagramPacket(receiveBuffer, 0, receiveBuffer.length);                socket.receive(receivePacket);                //真正接收到响应，进行字符集解码处理                String response = new String(receiveBuffer, 0, receivePacket.getLength(),"UTF-8");                System.out.printf("From 服务端$|%s|%n", response);            }        }    }}