RPC框架之RMI(一)

- 日理万妓 2023-08-17 15:30 73阅读 0赞

## 一.rmi ##

远程方法调用，是java特有的一种RPC实现。

## 二.特性 ##

1.支持面向对象的多态性，优势之一

2.java独有，不支持其他语言

3.使用java原生序列化

4.BIO（异步阻塞IO）通信

由于使用原生序列化和异步阻塞io通信，导致该类型性能较差，不适合高并发场景。

## 三、实现 ##

### １．服务端。 ###

HelloService接口，继承Remote

package com.rmiServer;
    
    import java.rmi.Remote;
    import java.rmi.RemoteException;
    
    public interface HelloService extends Remote{
    	
    	String sayHello(String someOne) throws RemoteException;
    }

HelloServiceImpl为HelloService的实现类，需要继承UnicastRemoteObject。

package com.rmiServer.impl;
    
    import java.rmi.RemoteException;
    import java.rmi.server.UnicastRemoteObject;
    
    import com.rmiServer.HelloService;
    
    public class HelloServiceImpl extends UnicastRemoteObject implements HelloService{
    	
    	private static final long serialVersionUID = 6203776714625426526L;
    
    	public HelloServiceImpl() throws RemoteException {
    		super();
    	}
    
    	@Override
    	public String sayHello(String someOne) throws RemoteException {
    		return "Hello,"+someOne;
    	}
    
    }

CustomSocketFactory，自定义端口通信，因为通信端口是随机产生的，　有可能被防火墙拦截。

package com.rmiServer;
    
    import java.io.IOException;
    import java.net.ServerSocket;
    import java.net.Socket;
    import java.rmi.server.RMISocketFactory;
    
    public class CustomSocketFactory extends RMISocketFactory{
    
    	@Override
    	public Socket createSocket(String host, int port) throws IOException {
    		return new Socket(host,port);
    	}
    
    	@Override
    	public ServerSocket createServerSocket(int port) throws IOException {
    		
    		if(port==0){
    			port=8020;
    		}
    		System.out.println("rmi notify port  " + port);
    		return new ServerSocket(port);
    	}
    
    }

服务端启动类ServerMain

package com.rmiServer;
    
    import java.io.IOException;
    import java.rmi.AlreadyBoundException;
    import java.rmi.Naming;
    import java.rmi.registry.LocateRegistry;
    import java.rmi.server.RMISocketFactory;
    
    import com.rmiServer.impl.HelloServiceImpl;
    
    public class ServerMain {
    
    	public static void main(String[] args) {
    		try {
    			//创建服务
    			HelloService helloService=new HelloServiceImpl();
    			//注册服务
    			LocateRegistry.createRegistry(8010);
    			
    			//指定通信端口，防止被防火墙拦截
    			RMISocketFactory.setSocketFactory(new CustomSocketFactory());
    			Naming.bind("rmi://localhost:8010/helloService", helloService);
    			System.out.println("ServerMain Provide　RPC service now");
    		} catch ( AlreadyBoundException | IOException e) {
    			e.printStackTrace();
    		} 
    			
    	}
    }

### ２．客户端 ###

HelloService接口，与服务器端对应

客户端启动类

package com.rmiClient;
    
    import java.net.MalformedURLException;
    import java.rmi.Naming;
    import java.rmi.NotBoundException;
    import java.rmi.RemoteException;
    
    public class ClienMain {
    	
    	public static void main(String[] args) {
    		try {
    			//服务引入
    			com.rmiServer.HelloService helloService=(com.rmiServer.HelloService) Naming.lookup("rmi://localhost:8010/helloService");
    			System.out.println(helloService.sayHello("is Client"));
    		} catch (MalformedURLException | RemoteException | NotBoundException e) {
    			e.printStackTrace();
    		} 
    	}
    }

### ３。先启动服务器端，再启动客户端。 ###

结果

Hello,is Client