Source code

001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.camel.util;
018
019import java.lang.reflect.Field;
020import java.lang.reflect.Method;
021import java.lang.reflect.Modifier;
022import java.util.Arrays;
023
024import javax.swing.text.Document;
025
026/**
027 * Helper for working with reflection on classes.
028 * <p/>
029 * This code is based on org.apache.camel.spring.util.ReflectionUtils class.
030 */
031public final class ReflectionHelper {
032
033    private ReflectionHelper() {
034        // utility class
035    }
036
037    /**
038     * Callback interface invoked on each field in the hierarchy.
039     */
040    @FunctionalInterface
041    public interface FieldCallback {
042
043        /**
044         * Perform an operation using the given field.
045         *
046         * @param field the field to operate on
047         */
048        void doWith(Field field) throws IllegalArgumentException, IllegalAccessException;
049    }
050
051    /**
052     * Action to take on each method.
053     */
054    @FunctionalInterface
055    public interface MethodCallback {
056
057        /**
058         * Perform an operation using the given method.
059         *
060         * @param method the method to operate on
061         */
062        void doWith(Method method) throws IllegalArgumentException, IllegalAccessException;
063    }
064
065    /**
066     * Action to take on each class.
067     */
068    @FunctionalInterface
069    public interface ClassCallback {
070
071        /**
072         * Perform an operation using the given class.
073         *
074         * @param clazz the class to operate on
075         */
076        void doWith(Class<?> clazz) throws IllegalArgumentException, IllegalAccessException;
077    }
078
079    /**
080     * Perform the given callback operation on the nested (inner) classes.
081     *
082     * @param clazz class to start looking at
083     * @param cc    the callback to invoke for each inner class (excluding the class itself)
084     */
085    public static void doWithClasses(Class<?> clazz, ClassCallback cc) throws IllegalArgumentException {
086        // and then nested classes
087        Class<?>[] classes = clazz.getDeclaredClasses();
088        for (Class<?> aClazz : classes) {
089            try {
090                cc.doWith(aClazz);
091            } catch (IllegalAccessException ex) {
092                throw new IllegalStateException("Shouldn't be illegal to access class '" + aClazz.getName() + "': " + ex);
093            }
094        }
095    }
096
097    /**
098     * Invoke the given callback on all fields in the target class, going up the class hierarchy to get all declared
099     * fields.
100     *
101     * @param clazz the target class to analyze
102     * @param fc    the callback to invoke for each field
103     */
104    public static void doWithFields(Class<?> clazz, FieldCallback fc) throws IllegalArgumentException {
105        // Keep backing up the inheritance hierarchy.
106        Class<?> targetClass = clazz;
107        do {
108            Field[] fields = targetClass.getDeclaredFields();
109            for (Field field : fields) {
110                try {
111                    fc.doWith(field);
112                } catch (IllegalAccessException ex) {
113                    throw new IllegalStateException("Shouldn't be illegal to access field '" + field.getName() + "': " + ex);
114                }
115            }
116            targetClass = targetClass.getSuperclass();
117        } while (targetClass != null && targetClass != Object.class);
118    }
119
120    /**
121     * Perform the given callback operation on all matching methods of the given class and superclasses (or given
122     * interface and super-interfaces).
123     * <p/>
124     * <b>Important:</b> This method does not take the {@link java.lang.reflect.Method#isBridge() bridge methods} into
125     * account.
126     *
127     * @param clazz class to start looking at
128     * @param mc    the callback to invoke for each method
129     */
130    public static void doWithMethods(Class<?> clazz, MethodCallback mc) throws IllegalArgumentException {
131        // Keep backing up the inheritance hierarchy.
132        Method[] methods = clazz.getDeclaredMethods();
133        for (Method method : methods) {
134            if (method.isBridge()) {
135                // skip the bridge methods which in Java 8 leads to problems with inheritance
136                // see https://bugs.openjdk.java.net/browse/JDK-6695379
137                continue;
138            }
139            try {
140                mc.doWith(method);
141            } catch (IllegalAccessException ex) {
142                throw new IllegalStateException("Shouldn't be illegal to access method '" + method.getName() + "': " + ex);
143            }
144        }
145        if (clazz.getSuperclass() != null) {
146            doWithMethods(clazz.getSuperclass(), mc);
147        } else if (clazz.isInterface()) {
148            for (Class<?> superIfc : clazz.getInterfaces()) {
149                doWithMethods(superIfc, mc);
150            }
151        }
152    }
153
154    /**
155     * Attempt to find a {@link Method} on the supplied class with the supplied name and parameter types. Searches all
156     * superclasses up to {@code Object}.
157     * <p>
158     * Returns {@code null} if no {@link Method} can be found.
159     *
160     * @param  clazz      the class to introspect
161     * @param  name       the name of the method
162     * @param  paramTypes the parameter types of the method (may be {@code null} to indicate any signature)
163     * @return            the Method object, or {@code null} if none found
164     */
165    public static Method findMethod(Class<?> clazz, String name, Class<?>... paramTypes) {
166        ObjectHelper.notNull(clazz, "Class must not be null");
167        ObjectHelper.notNull(name, "Method name must not be null");
168        Class<?> searchType = clazz;
169        while (searchType != null) {
170            Method[] methods = searchType.isInterface() ? searchType.getMethods() : searchType.getDeclaredMethods();
171            for (Method method : methods) {
172                if (name.equals(method.getName())
173                        && (paramTypes == null || Arrays.equals(paramTypes, method.getParameterTypes()))) {
174                    return method;
175                }
176            }
177            searchType = searchType.getSuperclass();
178        }
179        return null;
180    }
181
182    public static void setField(Field f, Object instance, Object value) {
183        try {
184            if (!Modifier.isPublic(f.getModifiers()) && !f.canAccess(instance)) {
185                f.setAccessible(true);
186            }
187            // must use fine-grained for the correct type when setting a field value via reflection
188            Class<?> type = f.getType();
189            if (boolean.class == type || Boolean.class == type) {
190                boolean val;
191                if (value instanceof Boolean) {
192                    val = (boolean) value;
193                } else {
194                    val = Boolean.parseBoolean(value.toString());
195                }
196                f.setBoolean(instance, val);
197            } else if (byte.class == type || Byte.class == type) {
198                byte val;
199                if (value instanceof Byte) {
200                    val = (byte) value;
201                } else {
202                    val = Byte.parseByte(value.toString());
203                }
204                f.setByte(instance, val);
205            } else if (int.class == type || Integer.class == type) {
206                int val;
207                if (value instanceof Integer) {
208                    val = (int) value;
209                } else {
210                    val = Integer.parseInt(value.toString());
211                }
212                f.setInt(instance, val);
213            } else if (long.class == type || Long.class == type) {
214                long val;
215                if (value instanceof Long) {
216                    val = (long) value;
217                } else {
218                    val = Long.parseLong(value.toString());
219                }
220                f.setLong(instance, val);
221            } else if (float.class == type || Float.class == type) {
222                float val;
223                if (value instanceof Float) {
224                    val = (float) value;
225                } else {
226                    val = Float.parseFloat(value.toString());
227                }
228                f.setFloat(instance, val);
229            } else if (double.class == type || Double.class == type) {
230                double val;
231                if (value instanceof Document) {
232                    val = (double) value;
233                } else {
234                    val = Double.parseDouble(value.toString());
235                }
236                f.setDouble(instance, val);
237            } else {
238                f.set(instance, value);
239            }
240        } catch (Exception ex) {
241            throw new UnsupportedOperationException("Cannot inject value of class: " + value.getClass() + " into: " + f);
242        }
243    }
244
245    public static Object getField(Field f, Object instance) {
246        try {
247            if (!Modifier.isPublic(f.getModifiers()) && !f.canAccess(instance)) {
248                f.setAccessible(true);
249            }
250            return f.get(instance);
251        } catch (Exception ex) {
252            // ignore
253        }
254        return null;
255    }
256
257}