RMI——hello world程序

迈不过友情╰ 2022-06-13 04:52 186阅读 0赞

# RMI——hello world程序 #

RMI作为分布式的基础之一，主要用来解决的问题是两个jvm进程间通讯的问题。RMI可以用作提供统一的服务接口和实现，方面各个系统间统一。

好，下面上货。

RMI分为服务端和客户端。下面我们先看一下服务端。

一、服务端。

1、服务端的目录结构截图：

![Center][]

2、MyRemote接口

package com.xueyou.demo.rmiserver.service;
    
    import com.xueyou.demo.rmiserver.dao.Student;
    
    import java.rmi.Remote;
    import java.rmi.RemoteException;
    
    public interface MyRemote extends Remote {
        public String sayHello() throws RemoteException;
    
        public Student sayStudent() throws RemoteException;
    }

3、MyRemoteImpl类

package com.xueyou.demo.rmiserver.serviceImpl;
    
    import com.xueyou.demo.rmiserver.dao.Student;
    import com.xueyou.demo.rmiserver.service.MyRemote;
    
    import java.rmi.RemoteException;
    import java.rmi.server.UnicastRemoteObject;
    
    public class MyRemoteImpl extends UnicastRemoteObject implements MyRemote {
    
        public String sayHello() throws RemoteException {
            return "hello world RMI";
        }
    
        public MyRemoteImpl() throws RemoteException {
        }
    
        public Student sayStudent() throws RemoteException {
            return new Student("xiaoming", 10);
        }
    }

4、Student实体类。这里需要注意的是实体类需要实现serializeble接口。

package com.xueyou.demo.rmiserver.dao;
    
    import java.io.Serializable;
    
    public class Student implements Serializable {
        private String name;
        private int age;
    
        public Student() {
        }
    
        public Student(String name, int age) {
            this.name = name;
            this.age = age;
        }
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public int getAge() {
            return age;
        }
    
        public void setAge(int age) {
            this.age = age;
        }
    }

5、启动服务类

package com.xueyou.demo.rmiserver;
    
    import com.xueyou.demo.rmiserver.service.MyRemote;
    import com.xueyou.demo.rmiserver.serviceImpl.MyRemoteImpl;
    
    import java.net.MalformedURLException;
    import java.rmi.AlreadyBoundException;
    import java.rmi.Naming;
    import java.rmi.RemoteException;
    import java.rmi.registry.LocateRegistry;
    
    public class App {
        public static void main(String[] args) {
            try {
                MyRemote service = new MyRemoteImpl();
                LocateRegistry.createRegistry(9191);
                try {
                    Naming.bind("rmi://192.168.0.113:9191/RemoteHello", service);
                } catch (AlreadyBoundException e) {
                    e.printStackTrace();
                }
            } catch (RemoteException e) {
                e.printStackTrace();
            } catch (MalformedURLException e) {
                e.printStackTrace();
            }
            System.out.println("success publish");
        }
    }

二、客户端  
首先看一下客户端的目录结构。需要注意的是，客户端的目录结构中，要调用的接口的包名和结构需要和服务端一致。这里一定要注意了，因为如果借口的包路径不一致的话，会出现ClassNotFoundException。

如图：

![Center 1][]

1、其他文件和服务端一致，这里只介绍如何调用RMI

package com.xueyou.demo.rmiclient;
    
    import com.xueyou.demo.rmiserver.dao.Student;
    import com.xueyou.demo.rmiserver.service.MyRemote;
    
    import java.net.MalformedURLException;
    import java.rmi.Naming;
    import java.rmi.NotBoundException;
    import java.rmi.RemoteException;
    
    public class App {
        public static void main(String[] args) {
            System.out.println("begin use RMI");
            try {
                MyRemote service = (MyRemote) Naming.lookup("rmi://192.168.0.113:9191/RemoteHello");
                String s = service.sayHello();
                Student student = service.sayStudent();
                System.out.println(s);
                System.out.println(student.getName());
                System.out.println(student.getAge());
            } catch (NotBoundException e) {
                e.printStackTrace();
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (RemoteException e) {
                e.printStackTrace();
            }
    
        }
    }

运行截图：

![Center 2][]

[Center]: /images/20220613/66d1d4d7ae7948f7b20712b21abe011a.png
[Center 1]: /images/20220613/f160ca80ad6542489b2fffa3d9e0c2de.png
[Center 2]: /images/20220613/9a86a3e06d4547fa96ac66faa029042b.png