1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.lang3;
18
19 import java.lang.annotation.Annotation;
20 import java.lang.reflect.Method;
21 import java.util.Arrays;
22
23 import org.apache.commons.lang3.builder.ToStringBuilder;
24 import org.apache.commons.lang3.builder.ToStringStyle;
25 import org.apache.commons.lang3.exception.UncheckedException;
26
27 /**
28 * Helper methods for working with {@link Annotation} instances.
29 *
30 * <p>This class contains various utility methods that make working with
31 * annotations simpler.</p>
32 *
33 * <p>{@link Annotation} instances are always proxy objects; unfortunately
34 * dynamic proxies cannot be depended upon to know how to implement certain
35 * methods in the same manner as would be done by "natural" {@link Annotation}s.
36 * The methods presented in this class can be used to avoid that possibility. It
37 * is of course also possible for dynamic proxies to actually delegate their
38 * e.g. {@link Annotation#equals(Object)}/{@link Annotation#hashCode()}/
39 * {@link Annotation#toString()} implementations to {@link AnnotationUtils}.</p>
40 *
41 * <p>#ThreadSafe#</p>
42 *
43 * @since 3.0
44 */
45 public class AnnotationUtils {
46
47 /**
48 * A style that prints annotations as recommended.
49 */
50 private static final ToStringStyle TO_STRING_STYLE = new ToStringStyle() {
51 /** Serialization version */
52 private static final long serialVersionUID = 1L;
53
54 {
55 setDefaultFullDetail(true);
56 setArrayContentDetail(true);
57 setUseClassName(true);
58 setUseShortClassName(true);
59 setUseIdentityHashCode(false);
60 setContentStart("(");
61 setContentEnd(")");
62 setFieldSeparator(", ");
63 setArrayStart("[");
64 setArrayEnd("]");
65 }
66
67 /**
68 * {@inheritDoc}
69 */
70 @Override
71 protected void appendDetail(final StringBuffer buffer, final String fieldName, Object value) {
72 if (value instanceof Annotation) {
73 value = AnnotationUtils.toString((Annotation) value);
74 }
75 super.appendDetail(buffer, fieldName, value);
76 }
77
78 /**
79 * {@inheritDoc}
80 */
81 @Override
82 protected String getShortClassName(final Class<?> cls) {
83 // formatter:off
84 return ClassUtils.getAllInterfaces(cls).stream().filter(Annotation.class::isAssignableFrom).findFirst()
85 .map(iface -> "@" + iface.getName())
86 .orElse(StringUtils.EMPTY);
87 // formatter:on
88 }
89
90 };
91
92 /**
93 * Helper method for comparing two arrays of annotations.
94 *
95 * @param a1 the first array
96 * @param a2 the second array
97 * @return a flag whether these arrays are equal
98 */
99 private static boolean annotationArrayMemberEquals(final Annotation[] a1, final Annotation[] a2) {
100 if (a1.length != a2.length) {
101 return false;
102 }
103 for (int i = 0; i < a1.length; i++) {
104 if (!equals(a1[i], a2[i])) {
105 return false;
106 }
107 }
108 return true;
109 }
110
111 /**
112 * Helper method for comparing two objects of an array type.
113 *
114 * @param componentType the component type of the array
115 * @param o1 the first object
116 * @param o2 the second object
117 * @return a flag whether these objects are equal
118 */
119 private static boolean arrayMemberEquals(final Class<?> componentType, final Object o1, final Object o2) {
120 if (componentType.isAnnotation()) {
121 return annotationArrayMemberEquals((Annotation[]) o1, (Annotation[]) o2);
122 }
123 if (componentType.equals(Byte.TYPE)) {
124 return Arrays.equals((byte[]) o1, (byte[]) o2);
125 }
126 if (componentType.equals(Short.TYPE)) {
127 return Arrays.equals((short[]) o1, (short[]) o2);
128 }
129 if (componentType.equals(Integer.TYPE)) {
130 return Arrays.equals((int[]) o1, (int[]) o2);
131 }
132 if (componentType.equals(Character.TYPE)) {
133 return Arrays.equals((char[]) o1, (char[]) o2);
134 }
135 if (componentType.equals(Long.TYPE)) {
136 return Arrays.equals((long[]) o1, (long[]) o2);
137 }
138 if (componentType.equals(Float.TYPE)) {
139 return Arrays.equals((float[]) o1, (float[]) o2);
140 }
141 if (componentType.equals(Double.TYPE)) {
142 return Arrays.equals((double[]) o1, (double[]) o2);
143 }
144 if (componentType.equals(Boolean.TYPE)) {
145 return Arrays.equals((boolean[]) o1, (boolean[]) o2);
146 }
147 return Arrays.equals((Object[]) o1, (Object[]) o2);
148 }
149
150 /**
151 * Helper method for generating a hash code for an array.
152 *
153 * @param componentType the component type of the array
154 * @param o the array
155 * @return a hash code for the specified array
156 */
157 private static int arrayMemberHash(final Class<?> componentType, final Object o) {
158 if (componentType.equals(Byte.TYPE)) {
159 return Arrays.hashCode((byte[]) o);
160 }
161 if (componentType.equals(Short.TYPE)) {
162 return Arrays.hashCode((short[]) o);
163 }
164 if (componentType.equals(Integer.TYPE)) {
165 return Arrays.hashCode((int[]) o);
166 }
167 if (componentType.equals(Character.TYPE)) {
168 return Arrays.hashCode((char[]) o);
169 }
170 if (componentType.equals(Long.TYPE)) {
171 return Arrays.hashCode((long[]) o);
172 }
173 if (componentType.equals(Float.TYPE)) {
174 return Arrays.hashCode((float[]) o);
175 }
176 if (componentType.equals(Double.TYPE)) {
177 return Arrays.hashCode((double[]) o);
178 }
179 if (componentType.equals(Boolean.TYPE)) {
180 return Arrays.hashCode((boolean[]) o);
181 }
182 return Arrays.hashCode((Object[]) o);
183 }
184
185 /**
186 * Checks if two annotations are equal using the criteria for equality
187 * presented in the {@link Annotation#equals(Object)} API docs.
188 *
189 * @param a1 the first Annotation to compare, {@code null} returns
190 * {@code false} unless both are {@code null}
191 * @param a2 the second Annotation to compare, {@code null} returns
192 * {@code false} unless both are {@code null}
193 * @return {@code true} if the two annotations are {@code equal} or both
194 * {@code null}
195 */
196 public static boolean equals(final Annotation a1, final Annotation a2) {
197 if (a1 == a2) {
198 return true;
199 }
200 if (a1 == null || a2 == null) {
201 return false;
202 }
203 final Class<? extends Annotation> type1 = a1.annotationType();
204 final Class<? extends Annotation> type2 = a2.annotationType();
205 Validate.notNull(type1, "Annotation %s with null annotationType()", a1);
206 Validate.notNull(type2, "Annotation %s with null annotationType()", a2);
207 if (!type1.equals(type2)) {
208 return false;
209 }
210 try {
211 for (final Method m : type1.getDeclaredMethods()) {
212 if (m.getParameterTypes().length == 0
213 && isValidAnnotationMemberType(m.getReturnType())) {
214 final Object v1 = m.invoke(a1);
215 final Object v2 = m.invoke(a2);
216 if (!memberEquals(m.getReturnType(), v1, v2)) {
217 return false;
218 }
219 }
220 }
221 } catch (final ReflectiveOperationException ex) {
222 return false;
223 }
224 return true;
225 }
226
227 /**
228 * Generate a hash code for the given annotation using the algorithm
229 * presented in the {@link Annotation#hashCode()} API docs.
230 *
231 * @param a the Annotation for a hash code calculation is desired, not
232 * {@code null}
233 * @return the calculated hash code
234 * @throws RuntimeException if an {@link Exception} is encountered during
235 * annotation member access
236 * @throws IllegalStateException if an annotation method invocation returns
237 * {@code null}
238 */
239 public static int hashCode(final Annotation a) {
240 int result = 0;
241 final Class<? extends Annotation> type = a.annotationType();
242 for (final Method m : type.getDeclaredMethods()) {
243 try {
244 final Object value = m.invoke(a);
245 if (value == null) {
246 throw new IllegalStateException(String.format("Annotation method %s returned null", m));
247 }
248 result += hashMember(m.getName(), value);
249 } catch (final ReflectiveOperationException ex) {
250 throw new UncheckedException(ex);
251 }
252 }
253 return result;
254 }
255
256 //besides modularity, this has the advantage of autoboxing primitives:
257 /**
258 * Helper method for generating a hash code for a member of an annotation.
259 *
260 * @param name the name of the member
261 * @param value the value of the member
262 * @return a hash code for this member
263 */
264 private static int hashMember(final String name, final Object value) {
265 final int part1 = name.hashCode() * 127;
266 if (ObjectUtils.isArray(value)) {
267 return part1 ^ arrayMemberHash(value.getClass().getComponentType(), value);
268 }
269 if (value instanceof Annotation) {
270 return part1 ^ hashCode((Annotation) value);
271 }
272 return part1 ^ value.hashCode();
273 }
274
275 /**
276 * Checks if the specified type is permitted as an annotation member.
277 *
278 * <p>The Java language specification only permits certain types to be used
279 * in annotations. These include {@link String}, {@link Class}, primitive
280 * types, {@link Annotation}, {@link Enum}, and single-dimensional arrays of
281 * these types.</p>
282 *
283 * @param type the type to check, {@code null}
284 * @return {@code true} if the type is a valid type to use in an annotation
285 */
286 public static boolean isValidAnnotationMemberType(Class<?> type) {
287 if (type == null) {
288 return false;
289 }
290 if (type.isArray()) {
291 type = type.getComponentType();
292 }
293 return type.isPrimitive() || type.isEnum() || type.isAnnotation()
294 || String.class.equals(type) || Class.class.equals(type);
295 }
296
297 /**
298 * Helper method for checking whether two objects of the given type are
299 * equal. This method is used to compare the parameters of two annotation
300 * instances.
301 *
302 * @param type the type of the objects to be compared
303 * @param o1 the first object
304 * @param o2 the second object
305 * @return a flag whether these objects are equal
306 */
307 private static boolean memberEquals(final Class<?> type, final Object o1, final Object o2) {
308 if (o1 == o2) {
309 return true;
310 }
311 if (o1 == null || o2 == null) {
312 return false;
313 }
314 if (type.isArray()) {
315 return arrayMemberEquals(type.getComponentType(), o1, o2);
316 }
317 if (type.isAnnotation()) {
318 return equals((Annotation) o1, (Annotation) o2);
319 }
320 return o1.equals(o2);
321 }
322
323 /**
324 * Generate a string representation of an Annotation, as suggested by
325 * {@link Annotation#toString()}.
326 *
327 * @param a the annotation of which a string representation is desired
328 * @return the standard string representation of an annotation, not
329 * {@code null}
330 */
331 public static String toString(final Annotation a) {
332 final ToStringBuilder builder = new ToStringBuilder(a, TO_STRING_STYLE);
333 for (final Method m : a.annotationType().getDeclaredMethods()) {
334 if (m.getParameterTypes().length > 0) {
335 continue; // wtf?
336 }
337 try {
338 builder.append(m.getName(), m.invoke(a));
339 } catch (final ReflectiveOperationException ex) {
340 throw new UncheckedException(ex);
341 }
342 }
343 return builder.build();
344 }
345
346 /**
347 * {@link AnnotationUtils} instances should NOT be constructed in
348 * standard programming. Instead, the class should be used statically.
349 *
350 * <p>This constructor is public to permit tools that require a JavaBean
351 * instance to operate.</p>
352 * @deprecated TODO Make private in 4.0.
353 */
354 @Deprecated
355 public AnnotationUtils() {
356 // empty
357 }
358 }