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让服务器继续使用DataInputStream监听输入流[重复]

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这个问题在这里已有答案：

我创建了一个java类TCPClient，它将Message对象发送到TCPServer . 我使用DataOutputStream和DataInputstream（这是我们被告知要执行的任务，我们必须同时使用它们才能将Object从客户端发送到服务器） . 这是我的TCPClient类

public class TCPClient {
public static final int PORT = 4000;
public static void main(String[] args){
    String hostname = "localhost";
    try(Socket client = new Socket(hostname,PORT);
        //BufferedReader in = new BufferedReader(new InputStreamReader(client.getInputStream()));
        BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in))) {

        Message message;
        String input;
        String the_message;
        double random;
        int id;
        while(!(input = stdIn.readLine()).equalsIgnoreCase("end")){
            random =  Math.random()*100;
            message = new Message();
            the_message = input;
            id = (int)random;
            message.setId(id);
            message.setMessage(the_message);
            encode(message,client);
            //System.out.println(in.readLine());
        }

    } catch (IOException e) {
        e.printStackTrace();
    }
}
private static void encode(Message message, Socket client) {
    try(DataOutputStream out = new DataOutputStream(client.getOutputStream())){
        out.writeUTF(message.getMessage());
        out.writeInt(message.getId());
    } catch (IOException e) {
        e.printStackTrace();
    }
}}

TCPServer类

public class TCPServer {
public static final int PORT = 4000;

public static void main(String[] args) {
    try (ServerSocket ss = new ServerSocket(PORT);
         Socket cs = ss.accept();
         //PrintWriter out = new PrintWriter(cs.getOutputStream(), true);
    ) {
        Message message = decode(cs);
        System.out.print("Message received: " + message.getMessage() + " id: " + message.getId());



    } catch (IOException e) {
        e.printStackTrace();
    }

}
private static Message decode(Socket client){
    Message message = new Message();
    try(DataInputStream in = new DataInputStream(client.getInputStream())){
       message.setMessage(in.readUTF());
        message.setId(in.readInt());
        return message;
    } catch (IOException e) {
        System.err.print("Error happened while decoding object");
        return null;
    }
}}

我不想做的是，当我从客户端发送新消息时，服务器关闭 . 我希望服务器继续监听消息 . 我该如何做到这一点？

试过这样的事情

while(cs.getInputStream().available()==0){
            Message message = decode(cs);
            System.out.println("Message received = " + message.getMessage() + " id " + message.getId());
        }

但没有工作

编辑：我不想构建一个多线程服务器来托管几个客户端 . 我希望单个服务器从唯一客户端接收多个消息，并在客户端发送“结束”时关闭套接字，我不知道是否可能 .

java sockets

1 回答

  • 0

    您的客户端最多只发送一条消息，因为 encode() 通过关闭套接字输出流来关闭套接字 . 如果您希望客户端发送多个消息，请尝试以下操作：

    public class TCPClient {
    // ...
    public static void main(String[] args) {
        try (Socket client = new Socket(hostname, PORT);
             BufferedReader stdIn = new BufferedReader(new InputStreamReader(System.in));
             DataOutputStream out = new DataOutputStream(client.getOutputStream())) {
            // ...
            while (!(input = stdIn.readLine()).equalsIgnoreCase("end")) {
                // ...
                encode(message, out);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static void encode(Message message, DataOutputStream out) throws IOException {
        out.writeUTF(message.getMessage());
        out.writeInt(message.getId());
    }
}

    服务器还会收到最多一条消息，因为 decode() 通过关闭其输入流来关闭套接字 . 这应该这样做：

    public class TCPServer {
    // ...
    public static void main(String[] args) {
        try (ServerSocket ss = new ServerSocket(PORT)) {
            // Accepts infinite clients.
            while (true) {
                try (Socket cs = ss.accept();
                     DataInputStream in = new DataInputStream(client.getInputStream())) {
                    boolean isClientOpen = true;
                    while (isClientOpen) {
                        try {
                            Message message = decode(in);
                            System.out.print("Message received: " + message.getMessage() + " id: " + message.getId());
                        } catch (IOException e) {
                            // The client may have closed the socket.
                            isClientOpen = false;
                        }
                    }
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private static Message decode(DataInputStream in) throws IOException {
        Message message = new Message();
        message.setMessage(in.readUTF());
        message.setId(in.readInt());
        return message;
    }
}
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