1 package org.apache.commons.digester3.annotations.utils;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import static org.apache.commons.beanutils.MethodUtils.invokeExactMethod;
23
24 import java.lang.annotation.Annotation;
25
26 /**
27 * Simple utility class to introspect annotations.
28 *
29 * @since 2.1
30 */
31 public class AnnotationUtils
32 {
33
34 /**
35 * The {@code value} string constant.
36 */
37 private static final String VALUE = "value";
38
39 /**
40 * The {@code pattern} string constant.
41 */
42 private static final String PATTERN = "pattern";
43
44 /**
45 * The {@code namespaceURI} string constant.
46 */
47 private static final String NAMESPACE_URI = "namespaceURI";
48
49 /**
50 * The {@code namespaceURI} string constant.
51 */
52 private static final String FIRE_ON_BEGIN = "fireOnBegin";
53
54 /**
55 * This class can't be instantiated.
56 */
57 private AnnotationUtils()
58 {
59 // this class can' be instantiated
60 }
61
62 /**
63 * Extract the {@code value()} from annotation.
64 *
65 * @param annotation the annotation has to be introspected.
66 * @return the annotation {@code value()}.
67 */
68 public static Object getAnnotationValue( Annotation annotation )
69 {
70 return invokeAnnotationMethod( annotation, VALUE );
71 }
72
73 /**
74 * Extract the {@code pattern()} from annotation.
75 *
76 * @param annotation the annotation has to be introspected.
77 * @return the annotation {@code pattern()}.
78 */
79 public static String getAnnotationPattern( Annotation annotation )
80 {
81 Object ret = invokeAnnotationMethod( annotation, PATTERN );
82 if ( ret != null )
83 {
84 return (String) ret;
85 }
86 return null;
87 }
88
89 /**
90 * Extract the {@code namespaceURI()} from annotation.
91 *
92 * @param annotation The annotation has to be introspected
93 * @return The annotation {@code namespaceURI()}
94 */
95 public static String getAnnotationNamespaceURI( Annotation annotation )
96 {
97 Object ret = invokeAnnotationMethod( annotation, NAMESPACE_URI );
98 if ( ret != null )
99 {
100 return (String) ret;
101 }
102 return null;
103 }
104
105 /**
106 * Extract the {@code fireOnBegin()} from annotation.
107 *
108 * @param annotation The annotation has to be introspected
109 * @return The annotation {@code fireOnBegin()}
110 */
111 public static boolean getFireOnBegin( Annotation annotation )
112 {
113 Object ret = invokeAnnotationMethod( annotation, FIRE_ON_BEGIN );
114 if ( ret != null )
115 {
116 return (Boolean) ret;
117 }
118 return false;
119 }
120
121 /**
122 * Extract the Annotations array {@code value()} from annotation if present, nul otherwise.
123 *
124 * @param annotation the annotation has to be introspected.
125 * @return the annotation {@code value()} as Annotations array.
126 */
127 public static Annotation[] getAnnotationsArrayValue( Annotation annotation )
128 {
129 Object value = getAnnotationValue( annotation );
130 if ( value != null && value.getClass().isArray()
131 && Annotation.class.isAssignableFrom( value.getClass().getComponentType() ) )
132 {
133 return (Annotation[]) value;
134 }
135 return null;
136 }
137
138 /**
139 * Invokes an annotation method.
140 *
141 * @param annotationn the annotation has to be introspected.
142 * @param method the method name to execute.
143 * @return the annotation method value, null if any error occurs.
144 */
145 private static Object invokeAnnotationMethod( Annotation annotation, String method )
146 {
147 try
148 {
149 return invokeExactMethod( annotation, method, null );
150 }
151 catch ( Throwable t )
152 {
153 return null;
154 }
155 }
156
157 }