java 利用 Socket 实现客户端与客户端通信

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原文链接: www.jianshu.com

网络通信,现在随处可见,任何东西不涉及网络的话,就感觉少了条手臂,断了个腿一样,今天就来聊聊网络通信;


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下面来看看socket的原理:


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  • 基于TCP的Socket编程

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下面来看看例子:

Server

import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;
import java.util.List;

//服务器类
public class Server {

    public static void main(String[] args) throws Exception {

        // 实例化一个list,用于保存所有的User
        List list = new ArrayList();
        // 创建绑定到特定端口的服务器套接字
        @SuppressWarnings("resource")
        ServerSocket serverSocket = new ServerSocket(9999);
        System.out.println("服务端正在开始~");
        // 循环监听客户端连接
        while (true) {
            Socket socket = serverSocket.accept();
            // 每接受一个线程,就随机生成一个一个新用户
            User user = new User("user" + Math.round(Math.random() * 100),socket);

            System.out.println(user.getName() + "正在登录。。。");
            list.add(user);
            // 创建一个新的线程,接收信息并转发
            ServerThread thread = new ServerThread(user, list);
            thread.start();
        }
    }
}

ServerThread

import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;

/*
 *   服务器线程的作用主要是:
 *   1.接收来自客户端的信息
 *   2.将接收到的信息解析,并转发给目标客户端
 * */
public class ServerThread extends Thread {

    private User user;
    private List list;

    public ServerThread(User user, List list) {
        this.user = user;
        this.list = list;
    }

    public void run() {
        try {
            while (true) {
                // 信息的格式:(login||logout||say),发送人,收发人,信息体
                //不断地读取客户端发过来的信息
                String msg= user.getBr().readLine();
                System.out.println(msg);
                String[] str = msg.split(",");
                switch (str[0]) {
                    case "logout":
                        remove(user);// 移除用户
                        break;
                    case "say":
                        sendToClient(str[1], msg); // 转发信息给特定的用户
                        break;
                    default:
                        break;
                }
            }
        } catch (Exception e) {
            System.out.println("异常");
        } finally {
            try {
                user.getBr().close();
                user.getSocket().close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private void sendToClient(String username, String msg) {

        for (User user : list) {
            if (user.getName().equals(username)) {
                try {
                    PrintWriter pw =user.getPw();
                    pw.println(msg);
                    pw.flush();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }

    private void remove(User user2) {
        list.remove(user2);
    }
}

Client

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

/*
 *   client线程主要是负责:
 *   1.发送信息
 *   2.一直接收信息,并解析
 * */
public class Client {

    public static void main(String[] args) {
        try {
            Socket socket = new Socket("localhost", 9999);
            //开启一个线程接收信息,并解析
            ClientThread thread=new ClientThread(socket);
            thread.setName("Client1");
            thread.start();
            //主线程用来发送信息
            BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
            PrintWriter out=new PrintWriter(socket.getOutputStream());
            while(true)
            {
                String s=br.readLine();
                out.println(s);
                //out.write(s+"\n");
                out.flush();
            }
        }catch(Exception e){
            System.out.println("服务器异常");
        }
    }
}

ClientThread

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.Socket;
/**
 *   作用:一直接收服务端转发过来的信息
 * */
public class ClientThread extends Thread {

    private Socket socket;
    public ClientThread(Socket socket) {
        this.socket = socket;
    }

    public void run() {
        try {
            InputStream inputStream = socket.getInputStream();
            InputStreamReader inputStreamReader = new InputStreamReader(
                    inputStream);
            BufferedReader br = new BufferedReader(inputStreamReader);
            try {
                // 信息的格式:(login||logout||say),发送人,收发人,信息体
                while (true) {
                    String msg=br.readLine();
                    System.out.println(msg);
                    String[] str = msg.split(",");
                    switch (str[0]) {
                        case "say":
                            System.out.println(str[2] + " 对   " + str[1] + " say:  "
                                    + str[3]);
                            break;
                        default:
                            break;
                    }
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        } catch (IOException e1) {
            e1.printStackTrace();
        }
    }
}

User

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

public class User {

    private String name;
    private String account;
    private Socket socket;
    private BufferedReader br;
    private PrintWriter pw;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAccount() {
        return account;
    }

    public void setAccount(String account) {
        this.account = account;
    }

    public Socket getSocket() {
        return socket;
    }

    public void setSocket(final Socket socket) {
        this.socket = socket;
    }

    public BufferedReader getBr() {
        return br;
    }

    public void setBr(BufferedReader br) {
        this.br = br;
    }

    public PrintWriter getPw() {
        return pw;
    }

    public void setPw(PrintWriter pw) {
        this.pw = pw;
    }

    public User(String name, final Socket socket) throws IOException {
        this.name = name;
        this.socket = socket;
        this.br = new BufferedReader(new InputStreamReader(
                socket.getInputStream()));
        this.pw = new PrintWriter(socket.getOutputStream());
    }

    @Override
    public String toString() {
        return "User [name=" + name + ", account=" + account + ", socket="
                + socket + "]";
    }
}

结果


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