通过JMS初步理解JNDI

JNDI服务模型
jndi-model

1、服务端

package com.neohope.jndi.test;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import java.io.IOException;
import java.rmi.RemoteException;
import java.rmi.registry.LocateRegistry;
import java.util.Hashtable;

/**
 * Created by Hansen on 2016/5/4.
 */
public class Server {
    private static InitialContext ctx;

    public static void initJNDI() {
        try {
            LocateRegistry.createRegistry(1234);
            final Hashtable jndiProperties = new Hashtable();
            jndiProperties.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.rmi.registry.RegistryContextFactory");
            jndiProperties.put(Context.PROVIDER_URL, "rmi://localhost:1234");
            ctx = new InitialContext(jndiProperties);
        } catch (NamingException e) {
            e.printStackTrace();
        } catch (RemoteException e) {
            e.printStackTrace();
        }
    }

    public static void bindJNDI(String name, Object obj) throws NamingException {
        ctx.bind(name, obj);
    }

    public static void unInitJNDI() throws NamingException {
        ctx.close();
    }

    public static void main(String[] args) throws NamingException, IOException {
        initJNDI();
        NeoMessage msg = new NeoMessage("Just A Message");
        bindJNDI("java:com/neohope/jndi/test01", msg);
        System.in.read();
        unInitJNDI();
    }
}

2、客户端

package com.neohope.jndi.test;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import java.util.Hashtable;

/**
 * Created by Hansen
 */
public class Client {
    public static void main(String[] args) throws NamingException {
        final Hashtable jndiProperties = new Hashtable();
        jndiProperties.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.rmi.registry.RegistryContextFactory");
        jndiProperties.put(Context.PROVIDER_URL, "rmi://localhost:1234");

        InitialContext ctx = new InitialContext(jndiProperties);
        NeoMessage msg = (NeoMessage) ctx.lookup("java:com/neohope/jndi/test01");
        System.out.println(msg.message);
        ctx.close();
    }
}

3、NeoMessage

package com.neohope.jndi.test;

import java.io.Serializable;
import java.rmi.Remote;

/**
 * Created by Hansen
 */
public class NeoMessage implements Remote, Serializable {
    public String message = "";

    public NeoMessage(String message)
    {
        this.message = message;
    }
}

大家可以看出,在这个简单的例子中:
1、服务端仅仅是把数据生成好,放到了LocateRegistry中。
2、而客户端,通过JNDI查到消息,获取到了对应的数据。
3、LocateRegistry完成了跨JVM/主机通讯的任务

反过来思考一下,对于JNDIL是不是更清楚一些了呢?
那再思考一下,那J2EE容器中的数据源是如何统一管理的呢?

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