1 /*
   2  * Copyright (c) 2000, 2004, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.jndi.url.dns;
  27 
  28 
  29 import java.util.Hashtable;
  30 
  31 import javax.naming.*;
  32 import javax.naming.spi.ObjectFactory;
  33 
  34 
  35 /**
  36  * A DNS URL context factory creates contexts that can resolve names
  37  * that are DNS pseudo-URLs.
  38  * In addition, if given a specific DNS URL (or an array of them), the
  39  * factory will resolve all the way to the named context.
  40  * See com.sun.jndi.dns.DnsUrl for a description of the URL format.
  41  *
  42  * @author Scott Seligman
  43  */
  44 
  45 
  46 public class dnsURLContextFactory implements ObjectFactory {
  47 
  48     public Object getObjectInstance(Object urlInfo, Name name,
  49                                     Context nameCtx, Hashtable<?,?> env)
  50             throws NamingException {
  51 
  52         if (urlInfo == null) {
  53             return (new dnsURLContext(env));
  54         } else if (urlInfo instanceof String) {
  55             return getUsingURL((String) urlInfo, env);
  56         } else if (urlInfo instanceof String[]) {
  57             return getUsingURLs((String[]) urlInfo, env);
  58         } else {
  59             throw (new ConfigurationException(
  60                     "dnsURLContextFactory.getObjectInstance: " +
  61                     "argument must be a DNS URL String or an array of them"));
  62         }
  63     }
  64 
  65     private static Object getUsingURL(String url, Hashtable<?,?> env)
  66             throws NamingException {
  67 
  68         dnsURLContext urlCtx = new dnsURLContext(env);
  69         try {
  70             return urlCtx.lookup(url);
  71         } finally {
  72             urlCtx.close();
  73         }
  74     }
  75 
  76     /*
  77      * Try each URL until lookup() succeeds for one of them.
  78      * If all URLs fail, throw one of the exceptions arbitrarily.
  79      * Not pretty, but potentially more informative than returning null.
  80      */
  81     private static Object getUsingURLs(String[] urls, Hashtable<?,?> env)
  82             throws NamingException {
  83 
  84         if (urls.length == 0) {
  85             throw (new ConfigurationException(
  86                     "dnsURLContextFactory: empty URL array"));
  87         }
  88         dnsURLContext urlCtx = new dnsURLContext(env);
  89         try {
  90             NamingException ne = null;
  91             for (int i = 0; i < urls.length; i++) {
  92                 try {
  93                     return urlCtx.lookup(urls[i]);
  94                 } catch (NamingException e) {
  95                     ne = e;
  96                 }
  97             }
  98             throw ne;   // failure:  throw one of the exceptions caught
  99         } finally {
 100             urlCtx.close();
 101         }
 102     }
 103 }