Java 使用RMI

Posted 2020-11-01 潇雨危栏

Java 使用RMI

Java使用序列化的方式，可以实现远端的方法调用，在分工合作时非常方便。本文记录使用java标准库实现rmi

一、服务端

结构

.
├── pom.xml
├── src
│   ├── main
│   │   └── java
│   │       └── hello
│   │           ├── HelloImpl.java
│   │           ├── HelloServer.java
│   │           └── IHello.java
│   └── test
│       └── java
│           └── mycom
│               └── AppTest.java
└── target

IHello.java

package hello;

import java.rmi.Remote;
import java.rmi.RemoteException;

public interface IHello extends Remote {
    public String sayHelloToSomeBody(String someBodyName) throws RemoteException;

HelloImpl.java

package hello;

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

public class HelloImpl extends UnicastRemoteObject implements IHello {
    public HelloImpl() throws RemoteException {
        super();
    }
    public String sayHelloToSomeBody(String someBodyName) throws RemoteException {
        System.out.println("Connected sucessfully!");
        return "你好，" + someBodyName + "!";
    }
}

HelloServer.java

package hello;

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

public class HelloServer {
    public static void main(String args[]) {
        try {
            IHello rhello = new HelloImpl();
            LocateRegistry.createRegistry(8888);
            // 如果配置在远程服务器，把地址换成你的ip
            System.setProperty("java.rmi.server.hostname","127.0.0.1");
            Naming.bind("rmi://localhost:8888/RHello", rhello);
            System.out.println(">>>>>INFO:远程IHello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();
        }
    }
}

在服务端启动HelloServer.java就会在8888端口监听请求了

二、客户端

客户端只要分享接口文件就好了

启动代码

package hello;

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[]) {
        try {
            // 填写服务器ip
            IHello rhello = (IHello) Naming.lookup("rmi://127.0.0.1:8888/RHello");
            System.out.println(rhello.sayHelloToSomeBody("Erich"));
        } catch (NotBoundException e) {
        } catch (MalformedURLException e) {
            e.printStackTrace();
            e.printStackTrace();
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }
}

三、小结

可以看到，客户端只要得到接口文件就能执行操作，而具体的实现交给服务端完成，这种架构可以解耦调用和实现