多个客户端同时访问服务器 [英] Multiple clients access the server concurrently

问题描述

我正在登录屏幕，现在说我们有两个用户名：amit和ajay以及他们的密码：pass和word。现在我想要假设他们是在同一系统上打开的两个桌面应用程序。我希望多个客户端同时访问服务器。

I am having a login screen and now say we have 2 users with username:amit and ajay and their password: "pass" and "word".Now i want that suppose their are two desktop applications open on same system.I want that multiple clients access the server concurrently.

意思是在一个登录屏幕中输入amit输入用户名，然后他的线程应该睡眠，在第二个登录屏幕中让ajay输入他的用户名然后amit将再次输入他的密码后，ajay输入他的密码。如何在java中做？请帮助。

Meaning say in one login screen amit enters the username and then his thread should sleep and in second login screen let ajay enter his username then amit will again enter his password after that ajay enter his password.How to do it in java?Please help .

推荐答案

这里我正在与您分享一个很好的客户端服务器身份验证应用程序，其中一台服务器根据您的要求使用TCP协议与多个客户端进行通信。

Here I am sharing you a nice Client Server Authentication Application having one server that is communicating with multiple clients using TCP protocol as per your requirement.

答案：

此处每个客户端都在一个与服务器不同的线程中连接，该线程包含有关该服务器的所有信息。客户。它将解决您的并发问题。

Here each client is connected in a separate thread from server and that thread contains all the information about the client. It will solve your concurrency problem.

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请参阅内联注释以获得更多说明。

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See inline comments for more clarification.

注意：在 LiveChatClient.java 文件中替换主机名，然后在端口号运行此程序1234

Note: replace host name in LiveChatClient.java file before running this program at port no 1234

运行程序的步骤：

• 首次运行 LiveChatServer 仅限一次


• 然后为多个客户端运行 LiveChatClient 添加

• First run LiveChatServer only for single time
• Then run LiveChatClient for multiple clients as many as you want to add

以下是同一上下文中的另一个示例。请查看 具有多客户端通信的Java Server。

Here is one more sample in the same context. Please have a look at Java Server with Multiclient communication.

Opcode.java：

用于设置客户端 - 服务器通信协议的操作代码

Operation code that is used to set a client-server communication protocol

/**************** an interface to define different operation code **************/

public interface Opcode {
    int CLIENT_USERNAME = 1;
    int CLIENT_INVALID_USERNAME = 2;
    int CLIENT_PASSWORD = 3;
    int CLIENT_INVALID_PASSWORD = 4;
    int CLIENT_CONNECTED = 5;
}

LiveChatServer.java：

控制多个客户的单台服务器

Single server that is controlling multiple clients

/************************ Live Chat Server *******************/

import java.io.IOException;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.HashMap;
import java.util.LinkedHashMap;

public class LiveChatServer {

    // Connection state info
    private static LinkedHashMap<String, ClientThread> clientInfo = new LinkedHashMap<String, ClientThread>();

    // TCP Components
    private ServerSocket serverSocket;

    // Main Constructor
    public LiveChatServer() {

        startServer();// start the server
    }

    public void startServer() {
        String port = "1234";

        try {
            // in constractor we are passing port no, back log and bind address whick will be local
            // host
            // port no - the specified port, or 0 to use any free port.
            // backlog - the maximum length of the queue. use default if it is equal or less than 0
            // bindAddr - the local InetAddress the server will bind to

            int portNo = Integer.valueOf(port);
            serverSocket = new ServerSocket(portNo, 0, InetAddress.getLocalHost());
            System.out.println(serverSocket);

            System.out.println(serverSocket.getInetAddress().getHostName() + ":"
                    + serverSocket.getLocalPort());

            while (true) {
                Socket socket = serverSocket.accept();
                new ClientThread(socket);
            }
        } catch (IOException e) {
            System.out.println("IO Exception:" + e);
            System.exit(1);
        } catch (NumberFormatException e) {
            System.out.println("Number Format Exception:" + e);
            System.exit(1);
        }
    }

    public static HashMap<String, ClientThread> getClientInfo() {
        return clientInfo;
    }

    // *********************************** Main Method ********************

    public static void main(String args[]) {
        new LiveChatServer();
    }

}

LiveChatClient.java：

连接到单个服务器的多个客户端

Multiple clients connected to single server

/************************ Live Chat Client *******************/

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

public class LiveChatClient {
    private String chatName;
    private String password;
    private String serverAddress;

    // TCP Components
    private Socket socket;
    private BufferedReader in;
    private PrintWriter out;

    public LiveChatClient() {

        initHostName();
        runClient();// have fun
    }

    public void initHostName() {
        try {
            serverAddress = "<your system name>";
            if (serverAddress == null)
                System.exit(1);

            serverAddress = serverAddress.trim();
            if (serverAddress.length() == 0)// empty field
            {
                System.out.println("Server IP Address or Name can't be blank.");
                initHostName();
                return;
            }
            System.out.println("Trying to connect with server...\nServer IP Address:"
                    + serverAddress);

            // create socket
            InetAddress inetAddress = InetAddress.getByName(serverAddress);
            if (!inetAddress.isReachable(60000))// 60 sec
            {
                System.out
                        .println("Error! Unable to connect with server.\nServer IP Address may be wrong.");
                System.exit(1);
            }

            initPortNo();
        } catch (SocketException e) {
            System.out.println("Socket Exception:\n" + e);
            initHostName();
            return;
        } catch (IOException e) {
            initHostName();
            return;
        }
    }

    public void initPortNo() {
        try {

            String portNo = "1234";

            portNo = portNo.trim();
            if (portNo.length() == 0)// empty field
            {
                System.out.println("Server port No can't be blank.");
                initPortNo();
                return;
            }
            System.out.println("Trying to connect with server...\nServer Port No:" + portNo);

            socket = new Socket(serverAddress, 1234);
            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            out = new PrintWriter(socket.getOutputStream(), true);

        } catch (IOException e) {
            System.out.println("IO Exception:\n" + e);
            initPortNo();
            return;
        }
    }

    public void sendChatName() throws IOException {
        System.out.println("Enter user name:");
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String name = br.readLine();
        if (name == null)
            System.exit(1);

        // title case (get only first 9 chars of chat name)
        chatName = name.trim();

        if (name.length() == 0) {
            System.out.println("Please enter user name.");
            sendChatName();
            return;
        }

        // sending opcode first then sending chatName to the server
        out.println(Opcode.CLIENT_USERNAME);
        out.println(chatName);
    }

    public void sendPassword() throws IOException {
        System.out.println("Enter password:");
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String name = br.readLine();
        if (name == null)
            System.exit(1);

        // title case (get only first 9 chars of password)
        password = name.trim();

        if (name.length() == 0) {
            System.out.println("Please enter password.");
            sendPassword();
            return;
        }

        // sending opcode first then sending password to the server
        out.println(Opcode.CLIENT_PASSWORD);
        out.println(password);
    }

    public void runClient() {
        try {
            sendChatName();
            while (true) {
                int opcode = Integer.parseInt(in.readLine());
                switch (opcode) {
                    case Opcode.CLIENT_INVALID_USERNAME:
                        // this client is connecting
                        System.out.println(chatName + " is invalid user name. Try different one.");
                        sendChatName();

                        break;

                    case Opcode.CLIENT_PASSWORD:
                        sendPassword();

                        break;

                    case Opcode.CLIENT_INVALID_PASSWORD:
                        // this client is connecting
                        System.out.println(password + " is invalid password. Try different one.");
                        sendPassword();

                        break;

                    case Opcode.CLIENT_CONNECTED:
                        System.out.println(chatName + " is connected successfully.");

                        break;

                }
            }
        } catch (IOException e) {
            System.out.println("Client is closed...");
        }
    }

    // *********************************** Main Method ********************

    public static void main(String args[]) {
        new LiveChatClient();
    }

}

ClientThread.java：

多个线程由服务器1为每个客户端启动并包含有关所有连接客户端的信息

Multiple thread started by server one for each client and containing information about all connected clients

/************************ Client Thread *******************/

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.HashMap;
import java.util.Map;

public class ClientThread implements Runnable {
    // TCP Components
    private Socket socket;
    private BufferedReader in;
    private PrintWriter out;
    private String chatName;
    private String password;

    // seperate thread
    private Thread thread;

    // boolean variable to check that client is running or not
    private volatile boolean isRunning = true;

    // opcode
    private int opcode;
    private static Map<String, String> userpass = new HashMap<String, String>();

    static {
        userpass.put("amit", "pass");
        userpass.put("ajay", "word");
    }

    public ClientThread(Socket socket) {
        try {
            this.socket = socket;

            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            out = new PrintWriter(socket.getOutputStream(), true);

            thread = new Thread(this);
            thread.start();

        } catch (IOException e) {
            System.out.println(e);
        }
    }

    public void run() {
        try {
            while (isRunning) {
                if (!in.ready())
                    continue;

                opcode = Integer.parseInt(in.readLine());// getting opcode first from client
                switch (opcode) {
                    case Opcode.CLIENT_USERNAME:
                        chatName = in.readLine();

                        System.out.println(chatName + " is reqesting to connect.");
                        boolean result1 = userpass.containsKey(chatName);
                        if (result1) {
                            System.out.println(chatName + " is a valid username.");
                            out.println(Opcode.CLIENT_PASSWORD);
                        } else {
                            System.out.println(chatName + " is a invalid username.");
                            out.println(Opcode.CLIENT_INVALID_USERNAME);
                        }

                        break;

                    case Opcode.CLIENT_PASSWORD:
                        password = in.readLine();

                        System.out.println(chatName + " is reqesting to connect having password "
                                + password);
                        boolean result2 = userpass.get(chatName).equals(password);
                        if (result2) {
                            System.out.println(password + " is a valid password for username "
                                    + chatName);
                            out.println(Opcode.CLIENT_CONNECTED);
                        } else {
                            System.out.println(password + " is a invalid password for username "
                                    + chatName);
                            out.println(Opcode.CLIENT_INVALID_PASSWORD);
                        }

                        break;
                }
            }

            // close all connections
            out.close();
            in.close();
            socket.close();
        } catch (IOException e) {
            System.out.println(e);
        }
    }
}

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添加两个客户端时，这是输出。

服务器：

ServerSocket[addr=computerName/14.98.241.102,port=0,localport=1234]
computerName:1234
abc is reqesting to connect.
abc is a invalid username.
ajay is reqesting to connect.
ajay is a valid username.
ajay is reqesting to connect having password word
word is a valid password for username ajay
amit is reqesting to connect.
amit is a valid username.
amit is reqesting to connect having password word
word is a invalid password for username amit
amit is reqesting to connect having password pass
pass is a valid password for username amit

Client1 :( ajay）

Trying to connect with server...
Server IP Address:computerName
Trying to connect with server...
Server Port No:1234
Enter user name:
abc
abc is invalid user name. Try different one.
Enter user name:
ajay
Enter password:
word
ajay is connected successfully.

Client2 :( amit）

Trying to connect with server...
Server IP Address:computerName
Trying to connect with server...
Server Port No:1234
Enter user name:
amit
Enter password:
word
word is invalid password. Try different one.
Enter password:
pass
amit is connected successfully.

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使用此程序作为应用程序的初始启动程序。如果您想在程序中添加新功能，请告诉我。

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Use this program as initial starter for your application. Please let me know if you want to add new functionality in the program.

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