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package com.sun.jndi.url.dns;


import java.util.Hashtable;

import javax.naming.*;
import javax.naming.spi.ObjectFactory;


A DNS URL context factory creates contexts that can resolve names that are DNS pseudo-URLs. In addition, if given a specific DNS URL (or an array of them), the factory will resolve all the way to the named context. See com.sun.jndi.dns.DnsUrl for a description of the URL format.
Author:Scott Seligman
/** * A DNS URL context factory creates contexts that can resolve names * that are DNS pseudo-URLs. * In addition, if given a specific DNS URL (or an array of them), the * factory will resolve all the way to the named context. * See com.sun.jndi.dns.DnsUrl for a description of the URL format. * * @author Scott Seligman */
public class dnsURLContextFactory implements ObjectFactory { public Object getObjectInstance(Object urlInfo, Name name, Context nameCtx, Hashtable<?,?> env) throws NamingException { if (urlInfo == null) { return (new dnsURLContext(env)); } else if (urlInfo instanceof String) { return getUsingURL((String) urlInfo, env); } else if (urlInfo instanceof String[]) { return getUsingURLs((String[]) urlInfo, env); } else { throw (new ConfigurationException( "dnsURLContextFactory.getObjectInstance: " + "argument must be a DNS URL String or an array of them")); } } private static Object getUsingURL(String url, Hashtable<?,?> env) throws NamingException { dnsURLContext urlCtx = new dnsURLContext(env); try { return urlCtx.lookup(url); } finally { urlCtx.close(); } } /* * Try each URL until lookup() succeeds for one of them. * If all URLs fail, throw one of the exceptions arbitrarily. * Not pretty, but potentially more informative than returning null. */ private static Object getUsingURLs(String[] urls, Hashtable<?,?> env) throws NamingException { if (urls.length == 0) { throw (new ConfigurationException( "dnsURLContextFactory: empty URL array")); } dnsURLContext urlCtx = new dnsURLContext(env); try { NamingException ne = null; for (int i = 0; i < urls.length; i++) { try { return urlCtx.lookup(urls[i]); } catch (NamingException e) { ne = e; } } throw ne; // failure: throw one of the exceptions caught } finally { urlCtx.close(); } } }