通过 RMI 发送存储在 ArrayList 中的数据 [关闭]

Question

如果我希望客户端请求存储在服务器中的 ArrayList 中的文本数据，那么使用 Java RMI 的实现过程将如何？

请提供类图或示例代码。

Answer 1

为服务器和客户端定义一个接口（相同的包名）

package arrayListRMI;

import java.rmi.Remote;
import java.rmi.RemoteException;
import java.util.ArrayList;

public interface IArrayList extends Remote {
    public ArrayList<String> getText()  throws RemoteException;
    public void setText(ArrayList<String> text) throws RemoteException;
}

定义一个实用程序类Constants.java

package arrayListRMI;

public class Constants {    
    public static final String RMI_ID = "StackOverflowAnswer";
    public static final int RMI_PORT = 222 ;   
}

为IArrayList 添加一个实现（在服务器端）

package arrayListRMI;

import java.rmi.RemoteException;
import java.rmi.server.UnicastRemoteObject;
import java.util.ArrayList;


public class ArrayListImpl  extends UnicastRemoteObject implements IArrayList{

    private static final long serialVersionUID = 1L;
    private ArrayList<String> text;

    protected ArrayListImpl() throws RemoteException {
        super();
    }

    public ArrayList<String> getText() {
        return text;
    }

    public void setText(ArrayList<String> text) {
        this.text = text;
    }

}

因此，您可以通过实例化ArrayListImpl 在服务器端实例化ArrayList 或String（文本）并将其绑定到rmiregistry，以便客户端可以随时请求它。

ArrayList<String> textRequested = new ArrayList<String>();
textRequested.add("example1");
textRequested.add("example2");
ArrayListImpl arrayListToSend = new ArrayListImpl();
arrayListToSend.setText(textRequested);

服务器

package arrayListRMI;

import java.rmi.AlreadyBoundException;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.sql.SQLException;


public class Server {
    public static void main(String args[]) throws AlreadyBoundException, SQLException, ClassNotFoundException {

        try {
            ArrayList<String> textRequested = new ArrayList<String>();
            textRequested.add("example1");
            textRequested.add("example2");
            ArrayListImpl arrayListToSend = new ArrayListImpl();
            arrayListToSend.setText(textRequested);
            Registry registry = LocateRegistry.createRegistry(Constants.RMI_PORT);
            registry.bind(Constants.RMI_ID, arrayListToSend);
            System.out.println("Server starts....");
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }
}

客户

package arrayListRMI;

import java.rmi.registry.LocateRegistry;
import java.rmi.registry.Registry;
import java.util.ArrayList;

public class Client {
    public static void main(String[] args) {
        try {
            Registry registry = LocateRegistry.getRegistry("localhost", Constants.RMI_PORT);
            IArrayList cmp = (IArrayList) registry.lookup(Constants.RMI_ID);
            ArrayList<String> received = cmp.getText();
            System.out.println(received);
        } catch (Exception e) {
            System.err.println("Client exception: " + e.toString());
            e.printStackTrace();
        }
    }
}

现在运行服务器。你得到这个输出

Server starts....

然后运行客户端。你得到这个输出

[example1, example2]