1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 *
19 */
20 package org.apache.directory.api.ldap.codec.api;
21
22
23 import org.slf4j.Logger;
24 import org.slf4j.LoggerFactory;
25
26
27 /**
28 * A factory that allows callers a means to get a handle on an LdapCodecService
29 * implementation regardless of the environment in which they're accessing it.
30 * In an OSGi environment, the BundleActivator binds the LdapCodecService
31 * class member forever to the DefaultLdapCodecService. If in
32 *
33 * In a standard standalone mode, the Bundle
34 *
35 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a>
36 */
37 public final class LdapApiServiceFactory
38 {
39 /** Logger for this class */
40 private static final Logger LOG = LoggerFactory.getLogger( LdapApiServiceFactory.class );
41
42 /** The LdapCodecService singleton bound to this factory */
43 private static LdapApiService ldapCodecService;
44
45 /** Whether or not the standalone implementation is being used */
46 private static boolean usingStandaloneImplementation;
47
48
49 /**
50 * Private constructor
51 */
52 private LdapApiServiceFactory()
53 {
54 }
55
56
57 /**
58 * Checks to see if the factory is initialized.
59 *
60 * @return true if initialized, false otherwise
61 */
62 public static boolean isInitialized()
63 {
64 return ldapCodecService != null;
65 }
66
67
68 /**
69 * Checks to see if the factory is using the standalone implementation.
70 *
71 * @return true if using the standalone implementation, false otherwise.
72 */
73 public static boolean isUsingStandaloneImplementation()
74 {
75 if ( !isInitialized() )
76 {
77 String msg = "Not initialized yet!";
78 LOG.error( msg );
79 throw new IllegalStateException( msg );
80 }
81
82 return usingStandaloneImplementation;
83 }
84
85
86 /**
87 * Gets the singleton instance of the LdapCodecService.
88 *
89 * @return a valid instance implementation based on environment and the
90 * availability of bindings.
91 */
92 public static LdapApiService getSingleton()
93 {
94 if ( ldapCodecService == null )
95 {
96 initialize( null );
97 }
98
99 return ldapCodecService;
100 }
101
102
103 /**
104 * Initialization can only take place once. There after an exception
105 * results.
106 *
107 * @param ldapCodecService The LDAP Codec Service to initialize with.
108 */
109 public static void initialize( LdapApiService ldapCodecService )
110 {
111 /*
112 * If the class member is already set we have problems.
113 */
114
115 if ( LdapApiServiceFactory.ldapCodecService != null )
116 {
117 StringBuilder sb = new StringBuilder( "The LdapCodecService is already set to an instance of " );
118 sb.append( LdapApiServiceFactory.class.getName() );
119 LOG.error( sb.toString() );
120 throw new IllegalStateException( sb.toString() );
121 }
122
123 /*
124 * If the argument is null, then we attempt discovery
125 */
126
127 if ( ldapCodecService == null )
128 {
129 try
130 {
131 @SuppressWarnings("unchecked")
132 Class<? extends LdapApiService> serviceClass = ( Class<? extends LdapApiService> )
133 Class.forName( "org.apache.directory.api.ldap.codec.standalone.StandaloneLdapApiService" );
134 LdapApiServiceFactory.ldapCodecService = serviceClass.newInstance();
135 usingStandaloneImplementation = true;
136 }
137 catch ( Exception e )
138 {
139 LOG.error( "Failed to instantiate a viable instance, instantiating new instance of ", e );
140 }
141 }
142 else
143 {
144 usingStandaloneImplementation = false;
145 LdapApiServiceFactory.ldapCodecService = ldapCodecService;
146 }
147 }
148 }