JNDI

JNDI

(Java Naming and Directory Interface,Java命名和目录接口)，为各种现有的命名和目录结构提供通用接口。

它由两部分组成：一是客户API，二是服务提供商接口（Service Provider Intergace）。应用程序通过客户API访问命名和目录服务，服务提供商接口用于供厂商创建命名和目录服务的JNDI实现。

API包结构

javax.naming
javax.naming.directory
javax.naming.event
javax.naming.ldap
javax.naming.spi

结构图

几个命名和目录服务的提供者：

• LDAP(Lightweight Directory Access Protocol)服务提供者
• CORBA COS（Common Object Request Broker Architecture Common Object Services）命名服务提供者 
• RMI(Java Remote Method Invocation)注册服务提供者
• DNS(Domain Name System)服务提供者.
• FSSP(File System Service Provider)文件系统服务提供者
• 其它服务提供者

DNS Service Provider为例进行示例代码演示

package com.joyen.learning.javase;

import java.util.Properties; 

import javax.naming.Context;
import javax.naming.NameClassPair;
import javax.naming.NamingEnumeration;
import javax.naming.directory.Attribute;
import javax.naming.directory.Attributes;
import javax.naming.directory.DirContext;
import javax.naming.directory.InitialDirContext;

public class TestDNSJndi {

    public static void main(String[] args) throws Exception {
        Properties env = new Properties(); 
        env.put(Context.INITIAL_CONTEXT_FACTORY, 
                "com.sun.jndi.dns.DnsContextFactory"); 
        //此IP一定要为要访问的DNS服务器的IP,可通过网络设置查看 
        env.put(Context.PROVIDER_URL, "dns://109.52.64.210"); 
        DirContext ctx = new InitialDirContext(env); 
        System.out.println("a:" + ctx); 
        DirContext ctx1 = (DirContext) ctx.lookup("www.baidu.com"); 
        System.out.println("b:" + ctx1);
        
        //从ctx.getAttributes("www.baidu.com")与ctx1.getAttributes("")结果一样 
        printAttributes("c:", ctx1.getAttributes("")); 
        printAttributes("d:", ctx.getAttributes("www.baidu.com"));
        
        Attributes attrs1 = ctx.getAttributes("www.baidu.com", new String[] { "a" }); 
        Attributes attrs2 = ctx1.getAttributes("", new String[] { "a" });
        printAttributes("e:", attrs1);
        printAttributes("f:", attrs2);
        
        System.out.println("nameParse:"+ctx1.getNameInNamespace());
        //list,此方法会导致程序lock 
        //listEnumation("list:",ctx.list(""));
    }

    public static void printAttributes(String tag, Attributes attres) throws Exception {
        for (NamingEnumeration<?> ae = attres.getAll(); ae.hasMore();) { 
            Attribute attr = (Attribute) ae.next(); 
            System.out.println(tag + "-----------------------------------------------
attribute: " + attr.getID());
            /* Print each value */
            for (NamingEnumeration<?> e = attr.getAll(); e.hasMore();System.out.println("value: " + e.next())); 
        }
    }

    public static void listEnumation(String tag, NamingEnumeration<?> name) throws Exception { 
        for (; name.hasMore();) {
            NameClassPair nameClass = (NameClassPair) name.next(); 
            System.out .println(tag + "-----------------------------------------------
attribute: " 
                                + nameClass.getName() + ":" + nameClass.getClassName()); 
        }
    }

}

运行结果：

a:javax.naming.directory.InitialDirContext@4a13ccea
b:com.sun.jndi.dns.DnsContext@51d77a8e
c:-----------------------------------------------
attribute: CNAME
value: www.a.shifen.com.
d:-----------------------------------------------
attribute: CNAME
value: www.a.shifen.com.
e:-----------------------------------------------
attribute: A
value: 180.97.33.108
value: 180.97.33.107
f:-----------------------------------------------
attribute: A
value: 180.97.33.107
value: 180.97.33.108
nameParse:www.baidu.com.

参考：

http://www.cnblogs.com/chinafine/archive/2010/06/16/1759246.html

http://www.cnblogs.com/chinafine/archive/2010/06/16/1759250.html