Java rmi小例子

1.创建接口，继续Remote接口

package com.rmi.server;

import java.rmi.Remote;
import java.rmi.RemoteException;
import java.util.Date;

public interface HelloService extends Remote {

	public String echo(String msg) throws RemoteException;

	public Date getDate() throws RemoteException;

}

2.创建服务类，继续Remote接口

package com.rmi.server;

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

public class HelloServiceImpl extends UnicastRemoteObject implements HelloService {

	private static final long serialVersionUID = 1L;

	String name;

	protected HelloServiceImpl(String name) throws RemoteException {
		this.name = name;
	}

	@Override
	public String echo(String msg) throws RemoteException {
		System.out.println(name + ":调用echo()方法");
		return "echo:" + msg + " from " + name;
	}

	@Override
	public Date getDate() throws RemoteException {
		System.out.println(name + ":调用getDate()方法");
		return new Date();
	}

}

3.绑定服务

package com.rmi.server;

import java.rmi.registry.LocateRegistry;

import javax.naming.Context;
import javax.naming.InitialContext;

public class SimpleServer {

	public static void main(String[] args) {
		try {
			HelloService service1 = new HelloServiceImpl("service1");
			HelloService service2 = new HelloServiceImpl("service2");

			Context namingContext = new InitialContext();
			// 之前一直报javax.naming.ServiceUnavailableException，加上此方法后才正常
			LocateRegistry.createRegistry(1099);
			namingContext.rebind("rmi://127.0.0.1:1099/HelloService1", service1);
			namingContext.rebind("rmi://127.0.0.1:1099/HelloService2", service2);
			System.out.println("服务器启动...");
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

4.客户端调用

package com.rmi.client;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NameClassPair;
import javax.naming.NamingEnumeration;

import com.rmi.server.HelloService;

public class SimpleClient {

	public static void showRemoteObjects(Context namingContext) throws Exception {
		NamingEnumeration<NameClassPair> e = namingContext.list("rmi:");
		while (e.hasMore()) {
			System.out.println(e.next().getName());
		}
	}

	public static void main(String[] args) {
		String url = "rmi://127.0.0.1:1099/";
		try {
			Context namingContext = new InitialContext();
			HelloService service1 = (HelloService) namingContext.lookup(url + "HelloService1");
			HelloService service2 = (HelloService) namingContext.lookup(url + "HelloService2");

			Class stubClass = service1.getClass();
			System.out.println("service1 是" + stubClass.getName() + "的实例");
			Class[] interfaces = stubClass.getInterfaces();
			for (int i = 0; i < interfaces.length; i++) {
				System.out.println("存根类实现了" + interfaces[i].getName() + "接口");
			}
			System.out.println(service1.echo("测试"));
			System.out.println(service1.getDate());
			System.out.println(service2.echo("测试2"));
			System.out.println(service2.getDate());

			showRemoteObjects(namingContext);
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
}

5.输出

服务端：

服务器启动...
service1:调用echo()方法
service1:调用getDate()方法
service2:调用echo()方法
service2:调用getDate()方法

客户端：

service1 是$Proxy0的实例
存根类实现了java.rmi.Remote接口
存根类实现了com.rmi.server.HelloService接口
echo:测试 from service1
Tue Jul 29 16:14:34 CST 2014
echo:测试2 from service2
Tue Jul 29 16:14:34 CST 2014
HelloService1
HelloService2

6.LocateRegistry.createRegistry(int port)

      java.rmi包中提供了类java.rmi.registry.LocateRegistry,用于获取名字服务或创建名字服务.调用LocateRegistry.createRegistry(int  port)方法可以在某一特定端口创建名字服务,从而用户无需再手工启动rmiregistry.此外,LocateRegistry.getRegistry(String  host,int  port)方法可用于获取名字服务.

 如果不写LocateRegistry.createRegistry(int port)，也可以运行命令start rmiregistry [port]启动注册表，默认1099端口