001/*
002 * Syncany, www.syncany.org
003 * Copyright (C) 2011-2016 Philipp C. Heckel <philipp.heckel@gmail.com>
004 *
005 * This program is free software: you can redistribute it and/or modify
006 * it under the terms of the GNU General Public License as published by
007 * the Free Software Foundation, either version 3 of the License, or
008 * (at your option) any later version.
009 *
010 * This program is distributed in the hope that it will be useful,
011 * but WITHOUT ANY WARRANTY; without even the implied warranty of
012 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
013 * GNU General Public License for more details.
014 *
015 * You should have received a copy of the GNU General Public License
016 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
017 */
018package org.syncany.util;
019
020import java.lang.annotation.Annotation;
021import java.lang.reflect.Constructor;
022import java.lang.reflect.Field;
023import java.lang.reflect.Method;
024import java.lang.reflect.Type;
025import java.util.ArrayList;
026import java.util.List;
027
028/**
029 * Utility class to find classes, methods and fields with certain properties -
030 * typically having an annotation or a certain erasure.
031 *
032 * @author Christian Roth (christian.roth@port17.de)
033 */
034public abstract class ReflectionUtil {
035        public static Field[] getAllFieldsWithAnnotation(Class<?> clazz, Class<? extends Annotation> annotation) {
036                List<Field> matchedAnnotations = new ArrayList<>();
037
038                while (clazz != null) {
039                        for (Field f : clazz.getDeclaredFields()) {
040                                if (f.isAnnotationPresent(annotation)) {
041                                        matchedAnnotations.add(f);
042                                }
043                        }
044                        
045                        clazz = clazz.getSuperclass();
046                }
047
048                return matchedAnnotations.toArray(new Field[matchedAnnotations.size()]);
049        }
050
051        public static Method[] getAllMethodsWithAnnotation(Class<?> clazz, Class<? extends Annotation> annotation) {
052                List<Method> matchedAnnotations = new ArrayList<>();
053
054                while (clazz != null) {
055                        for (Method m : clazz.getDeclaredMethods()) {
056                                if (m.isAnnotationPresent(annotation)) {
057                                        matchedAnnotations.add(m);
058                                }
059                        }
060                        
061                        clazz = clazz.getSuperclass();
062                }
063
064                return matchedAnnotations.toArray(new Method[matchedAnnotations.size()]);
065        }
066
067        public static Constructor<?> getMatchingConstructorForClass(Class<?> clazz, Class<?>... parameterTypes) {
068                // Try fast matching
069                try {
070                        return clazz.getConstructor(parameterTypes);
071                }
072                catch (NoSuchMethodException e) {
073                        // ignore
074                }
075
076                // If fast matching fails, check for assignable constructor
077                findConstructor: for (Constructor<?> constructor : clazz.getConstructors()) {
078                        if (constructor.getParameterTypes().length == parameterTypes.length) {
079                                int i = 0;
080
081                                for (Class<?> t : constructor.getParameterTypes()) {
082                                        // TODO [low] Handle type erasure (see test)
083                                        if (!parameterTypes[i].isAssignableFrom(t)) {
084                                                continue findConstructor;
085                                        }
086
087                                        ++i;
088                                }
089
090                                return constructor;
091                        }
092                }
093
094                return null;
095        }
096
097        /**
098         * Returns the {@link Class} from a {@link Type}, or
099         * returns null if the class is not found, or the type 
100         * is not a class.
101         */
102        public static Class<?> getClassFromType(Type type) {
103                // Java 7 does not support getTypeName() :(
104                String fullName = type.toString();
105
106                try {
107                        if (fullName.startsWith("class ")) {
108                                return Class.forName(fullName.substring("class ".length()));
109                        }
110                }
111                catch (ClassNotFoundException e) {
112                        return null;
113                }
114
115                return null;
116        }
117
118        public static boolean isAnnotationPresentInHierarchy(Class<?> clazz, Class<? extends Annotation> annotation) {
119                while (clazz != null) {
120                        if (clazz.isAnnotationPresent(annotation)) {
121                                return true;
122                        }
123                        
124                        clazz = clazz.getSuperclass();
125                }
126
127                return false;
128        }
129
130        public static <T extends Annotation> T getAnnotationInHierarchy(Class<?> clazz, Class<T> annotation) {
131                while (clazz != null) {
132                        if (clazz.isAnnotationPresent(annotation)) {
133                                return clazz.getAnnotation(annotation);
134                        }
135                        
136                        clazz = clazz.getSuperclass();
137                }
138
139                return null;
140        }
141
142        /**
143         * Returns whether or not the value is a valid value
144         * for the enum given.
145         * 
146         * @param checkEnumValue Value to check
147         * @param enumClass Enum class to check the given value against
148         * @return True if given value is valid, false otherwise 
149         */
150        @SuppressWarnings({ "unchecked", "rawtypes" })
151        public static boolean isValidEnum(String checkEnumValue, Class<?> enumClass) {
152                if (!enumClass.isEnum()) {
153                        return false;
154                }
155
156                try {
157                        Enum.valueOf((Class<? extends Enum>) enumClass, checkEnumValue);
158                        return true;
159                }
160                catch (IllegalArgumentException e) {
161                        return false;
162                }
163        }
164}