远程代理模式-Remote Proxy(Java实现)

远程代理模式-Remote Proxy

服务端通过rmi将对象注册到远程服务, 客户端使用时, 只需要通过rmi协议获取即可, 只要接口统一, 即可不需要知道内部具体实现, 直接调用使用.

CompareHelper接口

这里就是客户端和服务端统一的接口, 只需要服务端根据这个接口实现相应的功能, 然后注册上去, 客户端就可以根据这个接口来使用相应的功能.

import java.rmi.RemoteException;
import java.rmi.*;

/**
 * 定义一个远程接口，必须继承Remote接口，其中需要远程调用的方法须抛出RemoteException异常
 */
public interface CompareHelper<T> extends Remote {

    /**
     * 比较 object1 和 object2 的大小,
     * 如果object1大, 那么返回true
     * 如果object2大, 那么返回false
     */
    boolean compare(T object1, T object2) throws RemoteException;

    /**
     * 将object2的值连接到object1的后面
     */
    T append(T object1, T object2) throws RemoteException;
}

IntegerCompareHelper类

CompareHellper接口的其中一种实现. 用于处理Integer类型.

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

public class IntegerCompareHelper extends UnicastRemoteObject implements CompareHelper<Integer> {
    protected IntegerCompareHelper() throws RemoteException {
    }

    @Override
    public boolean compare(Integer object1, Integer object2) throws RemoteException {
        return object1 - object2 > 0;
    }

    @Override
    public Integer append(Integer object1, Integer object2) throws RemoteException {
        return Integer.valueOf(object1.toString() + object2.toString());
    }
}

StringCompareHelper类

CompareHellper接口的其中一种实现. 用于处理String类型.

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

public class StringCompareHelper extends UnicastRemoteObject implements CompareHelper<String> {

    protected StringCompareHelper() throws RemoteException {
    }

    @Override
    public boolean compare(String object1, String object2) throws RemoteException {
        return object1.compareTo(object2) > 0;
    }

    @Override
    public String append(String object1, String object2) throws RemoteException {
        return object1 + object2;
    }
}

Server类

用于注册服务到远程服务上.

import java.net.MalformedURLException;
import java.rmi.AlreadyBoundException;
import java.rmi.Naming;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;

/**
 * 创建RMI注册表，启动RMI服务，并将远程对象注册到RMI注册表中。
 */
public class Server {
    private static final String HOST = "localhost";
    private static final int PORT = 9090;

    public static void main(String args[]) {

        try {
            //创建2个对象, 准备将这个两个对象作为远程对象注册
            CompareHelper stringCompareHelper = new StringCompareHelper();
            CompareHelper integerCompareHelper = new IntegerCompareHelper();

            LocateRegistry.createRegistry(PORT);

            //绑定的URL标准格式为：rmi://host:port/name(其中协议名可以省略，下面两种写法都是正确的）
            // 本例子中就是 "rmi://localhost:9090/XXXXXXCompareHelper"
            Naming.bind("rmi://" + HOST + ":" + PORT + "/StringCompareHelper", stringCompareHelper);
            Naming.bind("//" + HOST + ":" + PORT + "/IntegerCompareHelper", integerCompareHelper);

            System.out.println("---->远程对象绑定成功！");
        } catch (RemoteException e) {
            System.out.println("创建远程对象发生异常！");
            e.printStackTrace();
        } catch (AlreadyBoundException e) {
            System.out.println("发生重复绑定对象异常！");
            e.printStackTrace();
        } catch (MalformedURLException e) {
            System.out.println("发生URL畸形异常！");
            e.printStackTrace();
        }
    }
}

Client类

用于调用远程服务.

import java.net.MalformedURLException;
import java.rmi.Naming;
import java.rmi.NotBoundException;
import java.rmi.RemoteException;

/**
 * 客户端测试，在客户端调用远程对象上的远程方法，并返回结果。
 */
@SuppressWarnings("unchecked")
public class Client {
    public static void main(String args[]) {
        try {
            CompareHelper compareHelper;

            compareHelper = (CompareHelper) Naming.lookup("rmi://localhost:9090/StringCompareHelper");
            System.out.println(compareHelper.append("你好", "哈哈哈"));
            System.out.println(compareHelper.compare("abc", "ioi"));

            compareHelper = (CompareHelper) Naming.lookup("rmi://localhost:9090/IntegerCompareHelper");
            System.out.println(compareHelper.append(6379, 8080));
            System.out.println(compareHelper.compare(435, 666));
        } catch (NotBoundException | MalformedURLException | RemoteException e) {
            e.printStackTrace();
        }
    }
}

如何运行呢?

先运行Server.java里的main方法来注册服务, 再运行Client.java里的main方法来进行相应服务的获取和调用.