Java-客戶端和服務器通信問題

Question

我正在嘗試創建一個簡單的Java聊天應用程序，但是遇到了一些問題。

這是下面兩個類的代碼：

Serveur.java：

import java.io.*;
import java.net.*;

class Serveur{

    private String msgClient, msgServeur;
    private ServerSocket serverSocket;
    private DataOutputStream out;
    private Socket socket;
    private int port;
    private BufferedReader in;

    public Serveur() throws IOException{
        System.out.println("Serveur OK...");
        this.port = 21;
        this.serverSocket = new ServerSocket(this.port);
        while(true){
            this.socket = serverSocket.accept();
            this.in = new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
            this.out = new DataOutputStream(this.socket.getOutputStream());
            this.msgClient = this.in.readLine();
            System.out.println("Received: " + this.msgClient);
            this.msgServeur = this.msgClient.toUpperCase() + '\n';
            send(this.msgServeur);
        }
    }

    public void send(String msg) throws IOException{
        this.out.writeBytes(msg);
    }

    public static void main(String argv[]) throws Exception {
        Serveur serveur = new Serveur();
    }
}

Client.java：

import java.io.*;
import java.net.*;

class Client{

    private String sentence;
    private String modifiedSentence;
    private int port;
    private BufferedReader inUser;
    private BufferedReader inServeur;
    private Socket socket;
    private DataOutputStream out;

    public Client() throws UnknownHostException, IOException{
        this.sentence = "";
        this.modifiedSentence = "";
        this.port = 21;
        this.inUser = new BufferedReader(new InputStreamReader(System.in));
        this.socket = new Socket("localhost", this.port);
        this.out = new DataOutputStream(this.socket.getOutputStream());
        this.inServeur = new BufferedReader(new InputStreamReader(this.socket.getInputStream()));
        sentence = this.inUser.readLine();
        this.out.writeBytes(sentence + '\n');
        modifiedSentence = this.inServeur.readLine();
        System.out.println("FROM SERVER: " + modifiedSentence);
        this.socket.close();
    }

    public static void main(String argv[]) throws Exception{
        Client client = new Client();
    }
}

我有2個問題：
-客戶端發送一條消息，服務器以大寫形式返回相同的消息。 如何允許客戶端發送消息而無需立即關閉其套接字連接？
-服務器看起來不錯，但是當我有多個客戶端時，有多個連接的客戶端會發生什么變化嗎？ 我如何向特定的客戶廣播消息和消息？

Answer 1

客戶端發送一條消息，服務器以大寫形式返回相同的消息。 我如何允許客戶端發送無限消息，並且在發送第一條消息后不破壞自身？

只是讓客戶使用循環

boolean quit = false;
while (!quit) {
    sentence = this.inUser.readLine();
    quit = sentence.trim().equals("quit");
    this.out.writeBytes(sentence + '\n');
    modifiedSentence = this.inServeur.readLine();
    System.out.println("FROM SERVER: " + modifiedSentence);
}
this.socket.close();

服務器看起來還可以，但是當我有多個客戶端時，多個客戶端之間會有區別嗎？ 我該如何播放？ 向重點客戶發送消息？

是的，該服務器阻止讀取第一個客戶端，因此任何其他客戶端都必須等待。 您可能希望將用於阻塞的代碼放在單獨的線程中，或將其提交給ExecutiveService。 而且，特定於客戶端的所有變量都不能位於單個服務器類中，因為您需要為每個客戶端設置一組變量。

while (true) {
    final Socket socket = serverSocket.accept();
    new Thread(() -> {
        try {
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            DataOutputStream out = new DataOutputStream(socket.getOutputStream());
            boolean quit = false;
            while (!quit) {
                String msgClient = in.readLine();
                quit = msgClient.trim().equals("quit");
                System.out.println("Received: " + msgClient);
                String msgServeur = msgClient.toUpperCase() + '\n';
                out.writeBytes(msgServeur);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }).start();
}