mirror of
https://github.com/kaka111222333/kaka111222333.github.io.git
synced 2025-12-22 09:45:05 +08:00
81 lines
2.4 KiB
Markdown
81 lines
2.4 KiB
Markdown
---
|
||
layout: post
|
||
title: RMI
|
||
tags: rmi Java
|
||
categories: java
|
||
---
|
||
|
||
Java RMI 指的是远程方法调用 (Remote Method Invocation)。RMI能够让在某个 Java 虚拟机上的对象调用另一个 Java 虚拟机中的对象上的方法, 其威力体现在它强大的开发分布式网络应用的能力上，它可以被看作是RPC的Java版本。
|
||
|
||
与WebService相比，RMI编写代码更加简单，在小型应用开发上更加合适，相对地，RMI只能在java中使用，而WebSerce可以跨平台。
|
||
|
||
RMI示意图：
|
||
|
||
![rmi][rmi]
|
||
|
||
# Demo
|
||
|
||
定义接口，必须继承Remote
|
||
|
||
~~~java
|
||
import java.rmi.Remote;
|
||
import java.rmi.RemoteException;
|
||
|
||
public interface HelloService extends Remote{
|
||
String sayHello() throws RemoteException;
|
||
}
|
||
~~~
|
||
|
||
实现接口，必须继承UnicastRemoteObject并在空构造中抛出RemoteException, 方法的返回值必须为原语类型或者序列化类型.
|
||
|
||
~~~java
|
||
import java.rmi.RemoteException;
|
||
import java.rmi.server.UnicastRemoteObject;
|
||
|
||
public class HelloServiceImpl extends UnicastRemoteObject implements HelloService {
|
||
|
||
protected HelloServiceImpl() throws RemoteException {}
|
||
|
||
@Override
|
||
public String sayHello() throws RemoteException {
|
||
return "server says. 'Hey'";
|
||
}
|
||
}
|
||
~~~
|
||
|
||
注册服务
|
||
|
||
~~~java
|
||
import java.net.MalformedURLException;
|
||
import java.rmi.RemoteException;
|
||
import java.rmi.registry.LocateRegistry;
|
||
import java.rmi.registry.Registry;
|
||
|
||
public class RegistryBook {
|
||
public static void main(String[] args) throws RemoteException, MalformedURLException {
|
||
Registry r = LocateRegistry.createRegistry(Registry.REGISTRY_PORT);
|
||
r.rebind("HelloService", new HelloServiceImpl());
|
||
}
|
||
}
|
||
~~~
|
||
|
||
在另一台虚拟机上运行客户端代码，需要获得服务接口文件
|
||
|
||
~~~java
|
||
import java.net.MalformedURLException;
|
||
import java.rmi.Naming;
|
||
import java.rmi.NotBoundException;
|
||
import java.rmi.RemoteException;
|
||
|
||
public class Client {
|
||
public static void main(String args[]) throws RemoteException, MalformedURLException, NotBoundException {
|
||
HelloService helloService = (HelloService) Naming.lookup("rmi://localhost:1099/HelloService");
|
||
System.out.println(helloService.sayHello());
|
||
}
|
||
}
|
||
~~~
|
||
|
||
注意，如果你使用的较为古老的jdk，你可能需要通过jdk内置的`rmic`命令生成`stub`以及`skeleton`文件，并将`stub`文件提供给客户端使用。
|
||
|
||
[rmi]: {{"/rmi.jpg" | prepend: site.imgrepo }}
|