摘要:

    
JNDI的架構(gòu)與JDBC的架構(gòu)非常類似.JNDI架構(gòu)提供了一組標(biāo)準(zhǔn)命名系統(tǒng)的API,這些API在JDK1.3之前是作為一個(gè)單獨(dú)的擴(kuò)展包jndi.jar(通過這個(gè)地址下載),這個(gè)基礎(chǔ)API構(gòu)建在與SPI之上。這個(gè)API提供如下五個(gè)包

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

它包括了幾個(gè)增強(qiáng)和下面的命名/目錄服務(wù)提供者：

• LDAP(Lightweight Directory Access Protocol)服務(wù)提供者
• CORBA COS（Common Object Request Broker Architecture Common Object Services）命名服務(wù)提供者 
• RMI(Java Remote Method Invocation)注冊(cè)服務(wù)提供者
• DNS(Domain Name System)服務(wù)提供者.
• FSSP(File System Service Provider)文件系統(tǒng)服務(wù)提供者
• 其它服務(wù)提供者

下面通過一個(gè)示例程序來說明JNDI工作原理(代碼為自解釋).

/*
    * Created on 2005-3-4
    *
    * To change the template for this generated file go to
    * Window>Preferences>Java>Code Generation>Code and Comments
    */
    package com.sily.jndi;
    import java.io.FileInputStream;
    import java.util.Properties;
    import javax.naming.Context;
    import javax.naming.InitialContext;
    /**
    * @author shizy
    *
    * To change the template for this generated type comment go to
    * Window>Preferences>Java>Code Generation>Code and Comments
    */
    public class TestJbossJNDI {
    /**
    *
    */
    public TestJbossJNDI() {
    super();
    // TODO Auto-generated constructor stub
    }
    public static void main(String[] args) { try {
    Properties env = new Properties();
    //載入jboss的SPI相關(guān)參數(shù),包括初始上下文工廠，服務(wù)URL，等等
    env.load(new FileInputStream("jbossJndi.properties"));
    env.list(System.out);
    //通過JNDI api 初始化上下文
    InitialContext ctx = new javax.naming.InitialContext(env);
    System.out.println("Got context");
    //create a subContext
    ctx.createSubcontext("/sylilzy");
    ctx.createSubcontext("sylilzy/sily");
    //rebind a object
    ctx.rebind("sylilzy/sily/a", "I am sily a!");
    ctx.rebind("sylilzy/sily/b", "I am sily b!");
    //lookup context
    Context ctx1=(Context)ctx.lookup("sylilzy");
    Context ctx2=(Context)ctx1.lookup("/sylilzy/sily");
    ctx2.bind("/sylilzy/g", "this is g");
    //lookup binded object
    Object o;
    o=ctx1.lookup("sily/a");
    System.out.println("get object from jndi:"+o);
    //rename the object
    ctx2.rename("/sylilzy/g", "g1");
    o=ctx2.lookup("g1");
    System.out.println("get object from jndi:"+o);
    } catch (Exception e) {
    e.printStackTrace();
    }
    }
    }
結(jié)果輸出如下:

/*
    * Created on 2005-3-4
    *
    * To change the template for this generated file go to
    * Window>Preferences>Java>Code Generation>Code and Comments
    */
    package com.sily.jndi;
    import java.io.FileInputStream;
    import java.util.Properties;
    import javax.naming.*;
    import javax.naming.Context;
    import javax.naming.InitialContext;
    /**
    * @author shizy
    *
    * To change the template for this generated type comment go to
    * Window>Preferences>Java>Code Generation>Code and Comments
    */
    public class ListJbossJndi {
    /**
    *
    */
    public ListJbossJndi() {
      super();
      // TODO Auto-generated constructor stub
     }
     public static void main(String[] args) {
      try {
       Properties env = new Properties();
       env.load(new FileInputStream("jbossJndi.properties"));
       //env.list(System.out);
       Context ctx = new InitialContext(env);
       listCtx(ctx.lookup("sylilzy"));
      }
      catch (Exception e) {
       e.printStackTrace();
      }
     }
     static void listCtx(Object o){
      if(!(o instanceof Context))log(":"+o);
      else {
       log("\n-----------------------------");
      try {
       Context ctx=(Context)o;
       //log(ctx.getNameInNamespace()+"/:");
       NamingEnumeration list=ctx.listBindings("");
       while(list.hasMore()){
        Binding bind=(Binding)list.next();
        log("\n/"+ctx.getNameInNamespace()+"/"+bind.getName());
        listCtx(bind.getObject());
       }
       log("\n-----------------------------");
      }
      catch (NamingException e) {
       // TODO Auto-generated catch block
       e.printStackTrace();
      }
     }
     }
     static void log(Object o){
      System.out.print(o);
     }
    }