com.almende.util.AnnotationUtil Maven / Gradle / Ivy
/**
* @file AnnotationUtil.java
*
* AnnotationUtil is a utility to get all annotations of a class, its methods,
* and the method parameters. Returned annotations include all annotations of
* the classes interfaces and super classes.
* Requested classes are cached, so requesting a classes annotations repeatedly
* is fast.
*
* Example usage:
*
* AnnotatedClass annotatedClass = AnnotationUtil.get(MyClass.class);
* List methods = annotatedClass.getMethods();
* for (AnnotatedMethod method : methods) {
* System.out.println("Method: " + method.getName());
* List annotations = method.getAnnotations();
* for (Annotation annotation : annotations) {
* System.out.println(" Annotation: " + annotation.toString());
* }
* }
*
* @brief
* AnnotationUtil is a utility to retrieve merged annotations from a class
* including all its superclasses and interfaces.
*
* @license
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy
* of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*
* Copyright (c) 2013 Almende B.V.
*
* @author Jos de Jong,
* @date 2013-01-21
*/
package com.almende.util;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
public class AnnotationUtil {
private static Map cache =
new ConcurrentHashMap();
private static Map cacheIncludingObject =
new ConcurrentHashMap();
/**
* Get all annotations of a class, methods, and parameters.
* Returned annotations include all annotations of the classes interfaces
* and super classes (excluding java.lang.Object).
* @param clazz
* @return annotatedClazz
*/
public static AnnotatedClass get(Class clazz) {
final boolean includeObject = false;
return get(clazz, includeObject);
}
/**
* Get all annotations of a class, methods, and parameters.
* Returned annotations include all annotations of the classes interfaces
* and super classes.
* @param clazz
* @param includeObject If true, methods of java.lang.Object will be
* included in the superclasses too.
* @return annotatedClazz
*/
public static AnnotatedClass get(Class clazz, boolean includeObject) {
Map _cache = includeObject ? cacheIncludingObject : cache;
AnnotatedClass annotatedClazz = _cache.get(clazz.getName());
if (annotatedClazz == null) {
annotatedClazz = new AnnotatedClass(clazz, includeObject);
_cache.put(clazz.getName(), annotatedClazz);
}
return annotatedClazz;
}
/**
* AnnotatedClass describes a class, its annotations, and its methods.
*/
public static class AnnotatedClass {
private Class clazz = null;
private List annotations = new ArrayList();
private List methods = new ArrayList();
/**
* Create a new AnnotatedClass
* @param clazz
* @param includeObject If true, the methods of super class
* java.lang.Object will be included too.
*/
public AnnotatedClass(Class clazz, boolean includeObject) {
this.clazz = clazz;
merge(clazz, includeObject);
}
/**
* Recursively merge a class into this AnnotatedClass.
* The method loops over all the classess interfaces and superclasses
* Methods with will be merged.
* @param clazz
* @param includeObject if true, superclass java.lang.Object will
* be included too.
*/
private void merge(Class clazz, boolean includeObject) {
Class c = clazz;
while (c != null && (includeObject || c != Object.class)) {
// merge the annotations
AnnotationUtil.merge(annotations, c.getDeclaredAnnotations());
// merge the methods
AnnotationUtil.merge(methods, c.getDeclaredMethods());
// merge all interfaces and the superclasses of the interfaces
for (Class i : c.getInterfaces()) {
merge(i, includeObject);
}
// ok now again for the superclass
c = c.getSuperclass();
}
}
/**
* Get the actual Java class described by this AnnotatedClass.
* @return clazz
*/
public Class getActualClass () {
return this.clazz;
}
/**
* Get all methods including methods declared in superclasses.
* @return methods
*/
public List getMethods () {
return methods;
}
/**
* Get all methods including methods declared in superclasses, filtered
* by name
* @param name
* @return filteredMethods
*/
public List getMethods (String name) {
List filteredMethods = new ArrayList();
for (AnnotatedMethod method : methods) {
if (method.getName().equals(name)) {
filteredMethods.add(method);
}
}
return filteredMethods;
}
/**
* Get all annotations defined on this class, its superclasses, and its
* interfaces
* @return annotations
*/
public List getAnnotations () {
return annotations;
}
/**
* Get an annotation of this class by type.
* Returns null if not available.
* @param annotationClass
* @return annotation
*/
@SuppressWarnings("unchecked")
public T getAnnotation (Class type) {
for (Annotation annotation : annotations) {
if (annotation.annotationType() == type) {
return (T) annotation;
}
}
return null;
}
}
/**
* AnnotatedMethod describes a method and its parameters.
*/
public static class AnnotatedMethod {
private Method method = null;
private String name = null;
private Class returnType = null;
private Type genericReturnType = null;
private List annotations = new ArrayList();
private List params = new ArrayList();
public AnnotatedMethod(Method method) {
this.method = method;
this.name = method.getName();
this.returnType = method.getReturnType();
this.genericReturnType = method.getGenericReturnType();
merge(method);
}
/**
* Merge a java method into this Annotated method.
* Annotations and parameter annotations will be merged.
* @param method
*/
private void merge(Method method) {
// merge the annotations
AnnotationUtil.merge(annotations, method.getDeclaredAnnotations());
// merge the params
Annotation[][] params = method.getParameterAnnotations();
Class[] types = method.getParameterTypes();
Type[] genericTypes = method.getGenericParameterTypes();
for (int i = 0; i < params.length; i++) {
if (i > this.params.size() - 1) {
this.params.add(new AnnotatedParam(params[i], types[i],
genericTypes[i]));
}
else {
this.params.get(i).merge(params[i]);
}
}
}
/**
* Get the actual Java method described by this AnnotatedMethod.
* @return method
*/
public Method getActualMethod () {
return method;
}
/**
* Get the method name
* @return name
*/
public String getName() {
return name;
}
/**
* Get the return type of the method
* @return returnType
*/
public Class getReturnType() {
return returnType;
}
/**
* Get the generic return type of the method
* @return genericType
*/
public Type getGenericReturnType() {
return genericReturnType;
}
/**
* Get all annotations of this method, defined in all implementations
* and interfaces of the class.
* @return annotations
*/
public List getAnnotations () {
return annotations;
}
/**
* Get an annotation of this method by type.
* Returns null if not available.
* @param annotationClass
* @return annotation
*/
@SuppressWarnings("unchecked")
public T getAnnotation (Class type) {
for (Annotation annotation : annotations) {
if (annotation.annotationType() == type) {
return (T) annotation;
}
}
return null;
}
/**
* Get all parameter annotations of this method, defined in all
* implementations and interfaces of the methods declaring class.
* @return params
*/
public List getParams() {
return params;
}
}
/**
* AnnotatedParam describes all annotations of a parameter.
*/
public static class AnnotatedParam {
private List annotations = new ArrayList();
private Class type = null;
private Type genericType = null;
private AnnotatedParam() {}
private AnnotatedParam(Annotation[] annotations, Class type, Type genericType) {
this.type = type;
this.genericType = genericType;
merge(annotations);
}
private void merge(Annotation[] annotations) {
// merge the annotations
AnnotationUtil.merge(this.annotations, annotations);
}
/**
* Get all annotations of this parameter, defined in all implementations
* and interfaces of the class.
* @return annotations
*/
public List getAnnotations () {
return annotations;
}
/**
* Get an annotation of this parameter by type.
* Returns null if not available.
* @param annotationClass
* @return annotation
*/
@SuppressWarnings("unchecked")
public T getAnnotation (Class type) {
for (Annotation annotation : annotations) {
if (annotation.annotationType() == type) {
return (T) annotation;
}
}
return null;
}
/**
* Get the type of the parameter
* @return type
*/
public Class getType() {
return type;
}
/**
* Get the generic type of the parameter
* @return genericType
*/
public Type getGenericType() {
return genericType;
}
}
/**
* Merge an array with annotations (listB) into a list with
* annotations (listA)
* @param listA
* @param listB
*/
private static void merge(List listA, Annotation[] listB) {
for (Annotation b : listB) {
boolean found = false;
for (Annotation a : listA) {
if (a.getClass() == b.getClass()) {
found = true;
break;
}
}
if (!found) {
listA.add(b);
}
}
}
/**
* Merge an array of methods (listB) into a list with method
* annotations (listA)
* @param listA
* @param listB
*/
private static void merge(List listA, Method[] listB) {
for (Method b : listB) {
AnnotatedMethod methodAnnotations = null;
for (AnnotatedMethod a : listA) {
if (equals(a.method, b)) {
methodAnnotations = a;
break;
}
}
if (methodAnnotations != null) {
methodAnnotations.merge(b);
}
else {
listA.add(new AnnotatedMethod(b));
}
}
}
/**
* Test if two methods have equal names, return type, param count,
* and param types
* @param a
* @param b
* @return
*/
private static boolean equals(Method a, Method b) {
// http://stackoverflow.com/q/10062957/1262753
if (!a.getName().equals(b.getName())) {
return false;
}
if (a.getReturnType() != b.getReturnType()) {
return false;
}
Class[] paramsa = a.getParameterTypes();;
Class[] paramsb = b.getParameterTypes();
if (paramsa.length != paramsb.length) {
return false;
}
for (int i = 0; i < paramsa.length; i++) {
if (paramsa[i] != paramsb[i]) {
return false;
}
}
return true;
}
}
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