java RMI - 服务器自动调用远程方法

Question

我正在尝试启动一个 RMI 程序，该程序将允许服务器向客户端发送 3 个问题，客户端将接受答案并将其发送回服务器。到目前为止，我在服务器上发送问题并获得答案，但服务器自动调用 getAnswer() 方法，并且该方法不存储用户输入的内容。

这是我运行服务器和客户端时得到的控制台结果:

    Server Started
0
0
Client connected, sending acknowledgement
received answer from client: 3

正如您所看到的，它在客户端连接之前调用了 getAnswer() 方法，因此尽管没有给出答案，但还是显示了 2 个值。 如何使服务器仅在我需要时调用这些方法？我尝试过循环和 if 语句，但我能想到的都不起作用!

服务器代码:

    import java.rmi.*;

public class Server
{

public static void main(String a[]) throws Exception
{
    int answer1, answer2, answer3;

    System.out.println("Server Started");
    try
    {
        Implement obj = new Implement(); 
        Naming.rebind("remote", obj);//register name with registry


        obj.sendQuestion(question1);
        answer1 = obj.getAnswer();

        obj.sendQuestion(question2);
        answer2 = obj.getAnswer();


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

}

static String question1 = "Q1: (A+B)*(A+B)\n1. A*A+B*B\n2. A*A+A*B+B*B\n3. A*A+2*A*B+B*B";
static String question2 = "Q2: (A+B)*(A-B)\n1. A*A+2*B*B\n2. A*A-B*B\n3. A*A-2*A*B+B*B";
static String question3 = "";
}

客户端代码:

    import java.rmi.*;
    import java.util.Scanner;

    public class Client
    {
      public static void main(String a[]) throws Exception
    {

    try {
        Interface obj = (Interface)Naming.lookup("remote"); //looks for object with add in name
        Interface m = (Interface) obj;
        System.out.println(obj.sendMessage()); //retrieve message from server

        System.out.println(obj.receiveQuestion());
        System.out.println("Please enter your answer");

        Scanner scan = new Scanner(System.in);

        int input = scan.nextInt();
        obj.test(input);
        System.out.println(obj.receiveQuestion());

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

}

}

接口(interface)代码:

    import java.rmi.Remote;

    public interface Interface extends Remote //becomes a remote interface
    {
    public String sendMessage() throws Exception;
    public void test(int message) throws Exception;
    public void sendQuestion(String message) throws Exception;
    public String receiveQuestion() throws Exception;
    public int getAnswer() throws Exception;

    }

实现代码:

    import java.rmi.server.*;

public class Implement extends UnicastRemoteObject implements Interface

{
String msg;
int answer;

public Implement() throws Exception //constructor to handle exceptions
{
    super();
}

public String sendMessage()
{
    String msg = "You have connected to the server";
    System.out.println("Client connected, sending acknowledgement");
    return msg;     
}

public void sendQuestion(String message)
{
    msg = message;
}

public String receiveQuestion()
{
    return msg;
}

public void test(int message)
{
    answer = message;
    System.out.println("received answer from client: " +answer);
}

public int getAnswer()
{

    System.out.println(answer);

    return answer;
}
}

Answer 1

你把这个从后到前。您正在服务器中调用自己的远程方法。 客户端应该调用远程方法。根据您的描述，您希望您的服务器是客户端，而您的客户端是服务器。