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     */
017    package org.apache.xbean.spring.context.impl;
018    
019    import org.springframework.beans.BeansException;
020    import org.springframework.beans.FatalBeanException;
021    import org.springframework.beans.MutablePropertyValues;
022    import org.springframework.beans.PropertyValue;
023    import org.springframework.beans.factory.FactoryBean;
024    import org.springframework.beans.factory.config.BeanDefinitionHolder;
025    import org.springframework.beans.factory.config.ConstructorArgumentValues;
026    import org.springframework.beans.factory.support.AbstractBeanDefinition;
027    
028    import java.lang.reflect.Constructor;
029    import java.lang.reflect.Method;
030    import java.util.ArrayList;
031    import java.util.Arrays;
032    import java.util.Collections;
033    import java.util.Comparator;
034    import java.util.HashMap;
035    import java.util.HashSet;
036    import java.util.Iterator;
037    import java.util.LinkedList;
038    import java.util.List;
039    import java.util.Map;
040    import 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     */
053    public 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    }