java的rmi

写在前面

本文看下如何通过Java原生提供的rmi功能来调用远端JVM对象的方法，并获取其结果。

1：定义远端service

pojo:

使用了lombok 。

@Getter
@Setter
@ToString
public class User implements Serializable {

    private static final long serialVersionUID = 6490921832856589236L;

    private String name;
    private Integer age;
    private String skill;

}

service:

public interface UserService extends Remote {

    /**
     * 查找用户
     * 
     * @param userId
     * @return
     * @throws RemoteException
     */
    User findUser(String userId) throws RemoteException;
}

public class UserServiceImpl extends UnicastRemoteObject implements UserService {

    protected UserServiceImpl() throws RemoteException {
    }

    @Override
    public User findUser(String userId) throws RemoteException {
        // 加载在查询
         if ("00001".equals(userId)) {
            User user = new User();
            user.setName("金庸");
            user.setAge(100);
            user.setSkill("写作");
            return user;
        }
        throw new RemoteException("查无此人");
    }
}

服务类:

public class RmiServer {

    public static void main(String[] args) {
        try {
            UserService userService = new UserServiceImpl();
            LocateRegistry.createRegistry(1900);
            Naming.rebind("rmi://localhost:1900/user", userService);
            System.out.println("start server,port is 1900");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

启动：

start server,port is 1900

2：定义client

public class RmiClient {
    public static void main(String args[]) {
        User answer;
        String userId = "00001";
        try {
            // lookup method to find reference of remote object
            UserService access = (UserService) Naming.lookup("rmi://localhost:1900/user");
            answer = access.findUser(userId);
            System.out.println("query:" + userId);
            System.out.println("result:" + answer);
        } catch (Exception ae) {
            System.out.println(ae);
        }
    }
}

存在用户输出：

query:00001
result:User(name=金庸, age=100, skill=写作)

Process finished with exit code 0

不存在用户输出：

java.rmi.ServerException: RemoteException occurred in server thread; nested exception is: 
	java.rmi.RemoteException: 查无此人

Process finished with exit code 0

写在后面

巨人的肩膀

Java的RMI介绍及使用方法详解 。