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.xbean.spring.context.impl;
018
019import org.springframework.beans.BeansException;
020import org.springframework.beans.FatalBeanException;
021import org.springframework.beans.MutablePropertyValues;
022import org.springframework.beans.PropertyValue;
023import org.springframework.beans.factory.FactoryBean;
024import org.springframework.beans.factory.config.BeanDefinitionHolder;
025import org.springframework.beans.factory.config.ConstructorArgumentValues;
026import org.springframework.beans.factory.support.AbstractBeanDefinition;
027
028import java.lang.reflect.Constructor;
029import java.lang.reflect.Method;
030import java.util.ArrayList;
031import java.util.Arrays;
032import java.util.Collections;
033import java.util.Comparator;
034import java.util.HashMap;
035import java.util.HashSet;
036import java.util.Iterator;
037import java.util.LinkedList;
038import java.util.List;
039import java.util.Map;
040import java.util.Set;
041
042/**
043 * NamedConstructorArgs is a BeanFactoryPostProcessor that converts property declarations into indexed constructor args
044 * based on the the constructor parameter names annotation.  This process first selects a constructor and then fills in
045 * the constructor arguments from the properties defined in the bean definition.  If a property is not defined in the
046 * bean definition, first the defaultValues map is checked for a value and if a value is not present a Java default
047 * value is provided for the constructor argument (e.g. numbers are assigned 0 and objects are assigned null).
048 *
049 * @author Dain Sundstrom
050 * @version $Id$
051 * @since 2.0
052 */
053public class NamedConstructorArgs {
054    private Map defaultValues = new HashMap();
055
056    /**
057     * Gets the default values that are assigned to constructor arguments without a defined value.
058     * @return the default values that are assigned to constructor arguments without a defined value
059     */
060    public List getDefaultValues() {
061        List values = new LinkedList();
062        for (Iterator iterator = defaultValues.entrySet().iterator(); iterator.hasNext();) {
063            Map.Entry entry = (Map.Entry) iterator.next();
064            PropertyKey key = (PropertyKey) entry.getKey();
065            Object value = entry.getValue();
066            values.add(new DefaultProperty(key.name, key.type, value));
067        }
068        return values;
069    }
070
071    /**
072     * Sets the default values that are assigned to constructor arguments without a defined value.
073     * @param defaultValues the values that are assigned to constructor arguments without a defined value
074     */
075    public void setDefaultValues(List defaultValues) {
076        this.defaultValues.clear();
077        for (Iterator iterator = defaultValues.iterator(); iterator.hasNext();) {
078            addDefaultValue((DefaultProperty) iterator.next());
079        }
080    }
081
082    /**
083     * Adds a default value for a property with the specified name and type.
084     * @param name the name of the property
085     * @param type the type of the property
086     * @param value the default value for a property with the specified name and type
087     */
088    public void addDefaultValue(String name, Class type, Object value) {
089        defaultValues.put(new PropertyKey(name, type), value);
090    }
091
092    /**
093     * Adds a defautl value for a property.
094     * @param defaultProperty the default property information
095     */
096    private void addDefaultValue(DefaultProperty defaultProperty) {
097        defaultValues.put(new PropertyKey(defaultProperty.getName(), defaultProperty.getType()), defaultProperty.getValue());
098    }
099
100    public void processParameters(BeanDefinitionHolder definitionHolder, MappingMetaData metadata) throws BeansException {
101        // this only works if we have an abstsract bean definition
102        if (!(definitionHolder.getBeanDefinition() instanceof AbstractBeanDefinition)) {
103            return;
104        }
105
106        AbstractBeanDefinition beanDefinition = (AbstractBeanDefinition) definitionHolder.getBeanDefinition();
107        ConstructorArgumentValues constructorArgumentValues = beanDefinition.getConstructorArgumentValues();
108
109        // if this bean already has constructor arguments defined, don't mess with them
110        if (constructorArgumentValues.getArgumentCount() > 0) {
111            return;
112        }
113
114        // try to get a list of constructor arg names to use
115        ConstructionInfo constructionInfo = selectConstructionMethod(beanDefinition, metadata);
116        if (constructionInfo == null) {
117            return;
118        }
119
120        // remove each named property and add an indexed constructor arg
121        MutablePropertyValues propertyValues = beanDefinition.getPropertyValues();
122        String[] parameterNames = constructionInfo.parameterNames;
123        Class[] parameterTypes = constructionInfo.parameterTypes;
124        for (int i = 0; i < parameterNames.length; i++) {
125            String parameterName = parameterNames[i];
126            Class parameterType = parameterTypes[i];
127
128            PropertyValue propertyValue = propertyValues.getPropertyValue(parameterName);
129            if (propertyValue != null) {
130                propertyValues.removePropertyValue(parameterName);
131                constructorArgumentValues.addIndexedArgumentValue(i, propertyValue.getValue(), parameterType.getName());
132            } else {
133                Object defaultValue = defaultValues.get(new PropertyKey(parameterName, parameterType));
134                if (defaultValue == null) {
135                    defaultValue = DEFAULT_VALUE.get(parameterType);
136                }
137                if (defaultValue instanceof FactoryBean) {
138                    try {
139                        defaultValue = ((FactoryBean)defaultValue).getObject();
140                    } catch (Exception e) {
141                        throw new FatalBeanException("Unable to get object value from bean factory", e);
142                    }
143                }
144                constructorArgumentValues.addIndexedArgumentValue(i, defaultValue, parameterType.getName());
145            }
146        }
147
148        // todo set any usable default values on the bean definition
149    }
150
151    private ConstructionInfo selectConstructionMethod(AbstractBeanDefinition beanDefinition, MappingMetaData metadata) {
152        Class beanClass = beanDefinition.getBeanClass();
153
154        // get a set containing the names of the defined properties
155        Set definedProperties = new HashSet();
156        PropertyValue[] values = beanDefinition.getPropertyValues().getPropertyValues();
157        for (int i = 0; i < values.length; i++) {
158            definedProperties.add(values[i].getName());
159        }
160
161        // first check for a factory method
162        if (beanDefinition.getFactoryMethodName() != null) {
163            return selectFactory(beanClass, beanDefinition, metadata, definedProperties);
164        } else {
165            return selectConstructor(beanClass, metadata, definedProperties);
166        }
167    }
168
169    private ConstructionInfo selectFactory(Class beanClass, AbstractBeanDefinition beanDefinition, MappingMetaData metadata, Set definedProperties) {
170        String factoryMethodName = beanDefinition.getFactoryMethodName();
171
172        // get the factory methods sorted by longest arg length first
173        Method[] methods = beanClass.getMethods();
174        List factoryMethods = new ArrayList(methods.length);
175        for (int i = 0; i < methods.length; i++) {
176            Method method = methods[i];
177            if (method.getName().equals(factoryMethodName)) {
178                factoryMethods.add(method);
179            }
180        }
181
182        Collections.sort(factoryMethods, new ArgLengthComparator());
183
184        // if a factory method has been annotated as the default constructor we always use that constructor
185        for (Iterator iterator = factoryMethods.iterator(); iterator.hasNext();) {
186            Method factoryMethod = (Method) iterator.next();
187
188            if (metadata.isDefaultFactoryMethod(beanClass, factoryMethod)) {
189                return new ConstructionInfo(beanClass, factoryMethod, metadata);
190            }
191        }
192
193        // try to find a constructor for which we have all of the properties defined
194        for (Iterator iterator = factoryMethods.iterator(); iterator.hasNext();) {
195            Method factoryMethod = (Method) iterator.next();
196            ConstructionInfo constructionInfo = new ConstructionInfo(beanClass, factoryMethod, metadata);
197            if (isUsableConstructor(constructionInfo, definedProperties)) {
198                return constructionInfo;
199            }
200        }
201        return null;
202    }
203
204    private ConstructionInfo selectConstructor(Class beanClass, MappingMetaData metadata, Set definedProperties) {
205        // get the constructors sorted by longest arg length first
206        List constructors = new ArrayList(Arrays.asList(beanClass.getConstructors()));
207        Collections.sort(constructors, new ArgLengthComparator());
208
209        // if a constructor has been annotated as the default constructor we always use that constructor
210        for (Iterator iterator = constructors.iterator(); iterator.hasNext();) {
211            Constructor constructor = (Constructor) iterator.next();
212
213            if (metadata.isDefaultConstructor(constructor)) {
214                return new ConstructionInfo(constructor, metadata);
215            }
216        }
217
218        // try to find a constructor for which we have all of the properties defined
219        for (Iterator iterator = constructors.iterator(); iterator.hasNext();) {
220            Constructor constructor = (Constructor) iterator.next();
221            ConstructionInfo constructionInfo = new ConstructionInfo(constructor, metadata);
222            if (isUsableConstructor(constructionInfo, definedProperties)) {
223                return constructionInfo;
224            }
225        }
226        return null;
227    }
228
229    private boolean isUsableConstructor(ConstructionInfo constructionInfo, Set definedProperties) {
230        // if we don't have parameter names this is not the constructor we are looking for
231        String[] parameterNames = constructionInfo.parameterNames;
232        if (parameterNames == null) {
233            return false;
234        }
235
236        Class[] parameterTypes = constructionInfo.parameterTypes;
237        for (int i = 0; i < parameterNames.length; i++) {
238            String parameterName = parameterNames[i];
239            Class parameterType = parameterTypes[i];
240
241            // can we satify this property using a defined property or default property
242            if (!definedProperties.contains(parameterName) && !defaultValues.containsKey(new PropertyKey(parameterName, parameterType))) {
243                return false;
244            }
245        }
246
247        return true;
248    }
249
250    private class ConstructionInfo {
251        private final Class[] parameterTypes;
252        private final String[] parameterNames;
253
254        public ConstructionInfo(Constructor constructor, MappingMetaData metadata) {
255            this.parameterTypes = constructor.getParameterTypes();
256            String[] names = metadata.getParameterNames(constructor);
257
258            // verify that we have enough parameter names
259            int expectedParameterCount = parameterTypes.length;
260            if (names != null && names.length != expectedParameterCount) {
261                throw new FatalBeanException("Excpected " + expectedParameterCount + " parameter names for constructor but only got " +
262                        names.length + ": " + constructor.toString());
263            }
264            if (expectedParameterCount == 0) {
265                names = new String[0];
266            }
267
268            this.parameterNames = names;
269        }
270
271        public ConstructionInfo(Class beanClass, Method factoryMethod, MappingMetaData metadata) {
272            this.parameterTypes = factoryMethod.getParameterTypes();
273
274            String[] names = metadata.getParameterNames(beanClass, factoryMethod);
275
276            // verify that we have enough parameter names
277            int expectedParameterCount = parameterTypes.length;
278            if (names != null && names.length != expectedParameterCount) {
279                throw new FatalBeanException("Excpected " + expectedParameterCount + " parameter names for factory method but only got " +
280                        names.length + ": " + factoryMethod.toString());
281            }
282            if (expectedParameterCount == 0) {
283                names = new String[0];
284            }
285
286            this.parameterNames = names;
287        }
288    }
289
290    private static class ArgLengthComparator implements Comparator {
291        public int compare(Object o1, Object o2) {
292            return getArgLength(o2) - getArgLength(o1);
293        }
294
295        private int getArgLength(Object object) {
296            if (object instanceof Method) {
297                return ((Method) object).getParameterTypes().length;
298            } else {
299                return ((Constructor) object).getParameterTypes().length;
300            }
301        }
302    }
303
304    private static class PropertyKey {
305        private final String name;
306        private final Class type;
307
308        public PropertyKey(String name, Class type) {
309            this.name = name;
310            this.type = type;
311        }
312
313        public boolean equals(Object object) {
314            if (!(object instanceof PropertyKey)) {
315                return false;
316            }
317
318            PropertyKey defaultProperty = (PropertyKey) object;
319            return name.equals(defaultProperty.name) && type.equals(type);
320        }
321
322        public int hashCode() {
323            int result = 17;
324            result = 37 * result + name.hashCode();
325            result = 37 * result + type.hashCode();
326            return result;
327        }
328
329        public String toString() {
330            return "[" + name + " " + type + "]";
331        }
332    }
333
334    private static final Map DEFAULT_VALUE;
335    static {
336        Map temp = new HashMap();
337        temp.put(Boolean.TYPE, Boolean.FALSE);
338        temp.put(Byte.TYPE, new Byte((byte) 0));
339        temp.put(Character.TYPE, new Character((char) 0));
340        temp.put(Short.TYPE, new Short((short) 0));
341        temp.put(Integer.TYPE, new Integer(0));
342        temp.put(Long.TYPE, new Long(0));
343        temp.put(Float.TYPE, new Float(0));
344        temp.put(Double.TYPE, new Double(0));
345
346        DEFAULT_VALUE = Collections.unmodifiableMap(temp);
347    }
348}