JNDI全攻略(二)目录（Directory）可看作是对命名（Naming）的一个扩充，一个目录对象不仅像命名一样，而且还提供
JNDI全攻略(二)
目录（Directory）可看作是对命名（Naming）的一个扩充，一个目录对象不仅像命名一样，而且还提供的对属性(Attributes)的操作.由API文档可知，javax.naming.directory.DirContext 类扩展自Context接口，同样，javax.naming.directory.InitialDirContext也扩展自 javax.naming.InitialContext,由此也可看出目录操作完全支持命名操作。下面给出一个DNS Service Provider例子以演示有关目录的一些操作：
?
<!-- Code creation by HtmlSave Eclipse Plug-in (C) 2005 Morten Moeller / eclipse.moelleryoung.com -->?*?Created?on?2005-11-17?
package?com.sily.jndi;?
import?java.util.Properties;?
/**?
?*?Description:?
?*??
?*?@author?shizy?
?*?@version?1.0?date:2005-11-17?
?*/?
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://10.17.45.239");?
????????DirContext?ctx?=?new?InitialDirContext(env);?
????????System.out.println("a:"?+?ctx);?
????????DirContext?ctx1?=?(DirContext)?ctx.lookup("www.sina.com");?
????????System.out.println("b:"?+?ctx1);?
????????printAttributes("c:",?ctx1.getAttributes(""));?
????????//从ctx.getAttributes("www.sina.com")与ctx1.getAttributes("")结果一样?
????????printAttributes("d:",?ctx.getAttributes("www.sina.com"));?
????????Attributes?attrs1?=?ctx.getAttributes("www.sina.com",?
????????????????new?String[]?{?"a"?});?
????????Attributes?attrs2?=?ctx.getAttributes("www.163.com",?
????????????????new?String[]?{?"a"?});?
????????Attributes?attrs3?=?ctx1.getAttributes("",?new?String[]?{?"a"?});?
????????Attributes?attrs4?=?ctx.getAttributes("www.baidu.com",?
????????????????new?String[]?{?"a"?});?
????????printAttributes("e:",?attrs1);?
????????printAttributes("f:",?attrs2);?
????????printAttributes("g:",?attrs3);?
????????printAttributes("attrs4:",?attrs4);?
?????????
????????System.out.println("nameParse:"+ctx1.getNameInNamespace());?
????????//list,此方法会导致程序lock?
????????//listEnumation("list:",ctx.list(""));?
????????//----------------------search?
????????Attributes?matchAttrs?=?new?BasicAttributes(true);?
????????matchAttrs.put(new?BasicAttribute("a",?"61.172.201.13"));?
????????NamingEnumeration?answer?=?ctx1.search("www.sina.com",?matchAttrs);?
????????printNamingEnumeration("search?:",?answer);?
????}?
????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?
????????????????????????????+?"-----------------------------------------------\nattribute:?"?
????????????????????????????+?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?
????????????????????????????+?"-----------------------------------------------\nattribute:?"?
????????????????????????????+?nameClass.getName()?+?":"?
????????????????????????????+?nameClass.getClassName());?
????????}?
????}?
????public?static?void?printNamingEnumeration(String?tag,?NamingEnumeration?e)?
????????????throws?Exception?{?
????????for?(;?e.hasMore();)?{?
????????????Attribute?attr?=?(Attribute)?e.next();?
????????????System.out?
????????????????????.println(tag?
????????????????????????????+?"-----------------------------------------------\nattribute:?"?
????????????????????????????+?attr.getID());?
????????????/*?Print?each?value?*/?
????????????for?(NamingEnumeration?ve?=?attr.getAll();?ve.hasMore();?System.out?
????????????????????.println("value:?"?+?ve.next()))?
????????????????;?
????????}?
????}?
}?
?
上例中，在jdk1.4中可运行通过。对于DNS Service Provider更详细的文档，大家可通过此URL下载：http://java.sun.com/products/jndi/downloads/index.html
上例一个可能运行结果如下：
a:javax.naming.directory.InitialDirContext@1bf216a
b:com.sun.jndi.dns.DnsContext@3a6727
c:-----------------------------------------------
attribute: CNAME
value: us.sina.com.cn.
d:-----------------------------------------------
attribute: CNAME
value: us.sina.com.cn.
e:-----------------------------------------------
attribute: A
value: 218.30.66.67
value: 218.30.66.68
value: 218.30.66.69
value: 218.30.66.70
value: 218.30.66.71
value: 218.30.66.56
value: 218.30.66.57
value: 218.30.66.58
value: 218.30.66.59
value: 218.30.66.60
value: 218.30.66.61
value: 218.30.66.62
value: 218.30.66.63
value: 218.30.66.64
value: 218.30.66.65
value: 218.30.66.66
f:-----------------------------------------------
attribute: A
value: 220.181.28.42
g:-----------------------------------------------
attribute: A
value: 218.30.66.68
value: 218.30.66.69
value: 218.30.66.70
value: 218.30.66.71
value: 218.30.66.56
value: 218.30.66.57
value: 218.30.66.58
value: 218.30.66.59
value: 218.30.66.60
value: 218.30.66.61
value: 218.30.66.62
value: 218.30.66.63
value: 218.30.66.64
value: 218.30.66.65
value: 218.30.66.66
value: 218.30.66.67
attrs4:-----------------------------------------------
attribute: A
value: 220.181.27.5
nameParse:www.sina.com.
Exception in thread "main" javax.naming.OperationNotSupportedException
at com.sun.jndi.dns.DnsContext.c_search(Unknown Source)
at com.sun.jndi.toolkit.ctx.ComponentDirContext.p_search(Unknown Source)
at com.sun.jndi.toolkit.ctx.PartialCompositeDirContext.search(Unknown Source)
at com.sun.jndi.toolkit.ctx.PartialCompositeDirContext.search(Unknown Source)
at com.sun.jndi.toolkit.ctx.PartialCompositeDirContext.search(Unknown Source)
at com.sily.jndi.TestDNSJndi.main(TestDNSJndi.java:57)
示例分析:
通过分析代码，我们可以看出我们从DNS服务器获取了指定域名的IP地址,而且可以看出www.sina.com有多个IP.
另外,可以看出从ctx.getAttributes("www.sina.com")得到的结果与ctx1.getAttributes("")结果一样,这便是目录操作的两种模式,这两种模式取得的结果是一样的,这点可以参考API文档(http://java.sun.com/j2se/1.5.0/docs/api/javax/naming/directory/DirContext.html):
There are two basic models of what attributes should be associated with. First, attributes may be directly associated with a DirContext object. In this model, an attribute operation on the named object is roughly...
另外,还有一点需要注意,从ctx.getAttributes()方法返回的Attributes中包含多个Attribute,每个Attribute包含多个values,其它详细内容请参考API文档
最后,代码NamingEnumeration?answer?=?ctx1.search("www.sina.com",?matchAttrs);试图对ctx1进行属性查找,但是抛出了异常,查看?DNS Service Provider 的文档可知,DNS Service Provider 没有提供对search方法的支持,大家可用其它的SP来测试此方法,如LDAP SP
总结:
此例只是简单地演示的JNDI的目录操作,对于目录操作的其它高级主题如Search,Search Scope,Count Limit,Composite Names 等没有详细介绍,请参考其它相关文档.
