    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.commons.configuration2.beanutils;
    018
    019import java.beans.PropertyDescriptor;
    020import java.lang.reflect.InvocationTargetException;
    021import java.util.ArrayList;
    022import java.util.Collection;
    023import java.util.Collections;
    024import java.util.HashMap;
    025import java.util.List;
    026import java.util.Map;
    027import java.util.Set;
    028import java.util.TreeSet;
    029
    030import org.apache.commons.beanutils.BeanUtilsBean;
    031import org.apache.commons.beanutils.ConvertUtilsBean;
    032import org.apache.commons.beanutils.DynaBean;
    033import org.apache.commons.beanutils.FluentPropertyBeanIntrospector;
    034import org.apache.commons.beanutils.PropertyUtilsBean;
    035import org.apache.commons.beanutils.WrapDynaBean;
    036import org.apache.commons.beanutils.WrapDynaClass;
    037import org.apache.commons.configuration2.ex.ConfigurationRuntimeException;
    038import org.apache.commons.lang3.ClassUtils;
    039
    040/**
    041 * <p>
    042 * A helper class for creating bean instances that are defined in configuration files.
    043 * </p>
    044 * <p>
    045 * This class provides utility methods related to bean creation operations. These methods simplify such operations
    046 * because a client need not deal with all involved interfaces. Usually, if a bean declaration has already been
    047 * obtained, a single method call is necessary to create a new bean instance.
    048 * </p>
    049 * <p>
    050 * This class also supports the registration of custom bean factories. Implementations of the {@link BeanFactory}
    051 * interface can be registered under a symbolic name using the {@code registerBeanFactory()} method. In the
    052 * configuration file the name of the bean factory can be specified in the bean declaration. Then this factory will be
    053 * used to create the bean.
    054 * </p>
    055 * <p>
    056 * In order to create beans using {@code BeanHelper}, create and instance of this class and initialize it accordingly -
    057 * a default {@link BeanFactory} can be passed to the constructor, and additional bean factories can be registered (see
    058 * above). Then this instance can be used to create beans from {@link BeanDeclaration} objects. {@code BeanHelper} is
    059 * thread-safe. So an instance can be passed around in an application and shared between multiple components.
    060 * </p>
    061 *
    062 * @since 1.3
    063 */
    064public final class BeanHelper {
    065
    066    /**
    067     * An implementation of the {@code BeanCreationContext} interface used by {@code BeanHelper} to communicate with a
    068     * {@code BeanFactory}. This class contains all information required for the creation of a bean. The methods for
    069     * creating and initializing bean instances are implemented by calling back to the provided {@code BeanHelper} instance
    070     * (which is the instance that created this object).
    071     */
    072    private static final class BeanCreationContextImpl implements BeanCreationContext {
    073        /** The association BeanHelper instance. */
    074        private final BeanHelper beanHelper;
    075
    076        /** The class of the bean to be created. */
    077        private final Class<?> beanClass;
    078
    079        /** The underlying bean declaration. */
    080        private final BeanDeclaration data;
    081
    082        /** The parameter for the bean factory. */
    083        private final Object param;
    084
    085        private BeanCreationContextImpl(final BeanHelper helper, final Class<?> beanClass, final BeanDeclaration data, final Object param) {
    086            beanHelper = helper;
    087            this.beanClass = beanClass;
    088            this.param = param;
    089            this.data = data;
    090        }
    091
    092        @Override
    093        public Object createBean(final BeanDeclaration data) {
    094            return beanHelper.createBean(data);
    095        }
    096
    097        @Override
    098        public Class<?> getBeanClass() {
    099            return beanClass;
    100        }
    101
    102        @Override
    103        public BeanDeclaration getBeanDeclaration() {
    104            return data;
    105        }
    106
    107        @Override
    108        public Object getParameter() {
    109            return param;
    110        }
    111
    112        @Override
    113        public void initBean(final Object bean, final BeanDeclaration data) {
    114            beanHelper.initBean(bean, data);
    115        }
    116    }
    117
    118    /**
    119     * A default instance of {@code BeanHelper} which can be shared between arbitrary components. If no special
    120     * configuration is needed, this instance can be used throughout an application. Otherwise, new instances can be created
    121     * with their own configuration.
    122     */
    123    public static final BeanHelper INSTANCE = new BeanHelper();
    124
    125    /**
    126     * A special instance of {@code BeanUtilsBean} which is used for all property set and copy operations. This instance was
    127     * initialized with {@code BeanIntrospector} objects which support fluent interfaces. This is required for handling
    128     * builder parameter objects correctly.
    129     */
    130    private static final BeanUtilsBean BEAN_UTILS_BEAN = initBeanUtilsBean();
    131
    132    /**
    133     * Copies matching properties from the source bean to the destination bean using a specially configured
    134     * {@code PropertyUtilsBean} instance. This method ensures that enhanced introspection is enabled when doing the copy
    135     * operation.
    136     *
    137     * @param dest the destination bean
    138     * @param orig the source bean
    139     * @throws NoSuchMethodException exception thrown by {@code PropertyUtilsBean}
    140     * @throws InvocationTargetException exception thrown by {@code PropertyUtilsBean}
    141     * @throws IllegalAccessException exception thrown by {@code PropertyUtilsBean}
    142     * @since 2.0
    143     */
    144    public static void copyProperties(final Object dest, final Object orig) throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
    145        BEAN_UTILS_BEAN.getPropertyUtils().copyProperties(dest, orig);
    146    }
    147
    148    /**
    149     * Creates a concrete collection instance to populate a property of type collection. This method tries to guess an
    150     * appropriate collection type. Mostly the type of the property will be one of the collection interfaces rather than a
    151     * concrete class; so we have to create a concrete equivalent.
    152     *
    153     * @param propName the name of the collection property
    154     * @param propertyClass the type of the property
    155     * @return the newly created collection
    156     */
    157    private static Collection<Object> createPropertyCollection(final String propName, final Class<?> propertyClass) {
    158        final Collection<Object> beanCollection;
    159
    160        if (List.class.isAssignableFrom(propertyClass)) {
    161            beanCollection = new ArrayList<>();
    162        } else if (Set.class.isAssignableFrom(propertyClass)) {
    163            beanCollection = new TreeSet<>();
    164        } else {
    165            throw new UnsupportedOperationException("Unable to handle collection of type : " + propertyClass.getName() + " for property " + propName);
    166        }
    167        return beanCollection;
    168    }
    169
    170    /**
    171     * Creates a {@code DynaBean} instance which wraps the passed in bean.
    172     *
    173     * @param bean the bean to be wrapped (must not be <b>null</b>)
    174     * @return a {@code DynaBean} wrapping the passed in bean
    175     * @throws IllegalArgumentException if the bean is <b>null</b>
    176     * @since 2.0
    177     */
    178    public static DynaBean createWrapDynaBean(final Object bean) {
    179        if (bean == null) {
    180            throw new IllegalArgumentException("Bean must not be null!");
    181        }
    182        final WrapDynaClass dynaClass = WrapDynaClass.createDynaClass(bean.getClass(), BEAN_UTILS_BEAN.getPropertyUtils());
    183        return new WrapDynaBean(bean, dynaClass);
    184    }
    185
    186    /**
    187     * Determines the class of the bean to be created. If the bean declaration contains a class name, this class is used.
    188     * Otherwise it is checked whether a default class is provided. If this is not the case, the factory's default class is
    189     * used. If this class is undefined, too, an exception is thrown.
    190     *
    191     * @param data the bean declaration
    192     * @param defaultClass the default class
    193     * @param factory the bean factory to use
    194     * @return the class of the bean to be created
    195     * @throws ConfigurationRuntimeException if the class cannot be determined
    196     */
    197    private static Class<?> fetchBeanClass(final BeanDeclaration data, final Class<?> defaultClass, final BeanFactory factory) {
    198        final String clsName = data.getBeanClassName();
    199        if (clsName != null) {
    200            try {
    201                return loadClass(clsName);
    202            } catch (final ClassNotFoundException cex) {
    203                throw new ConfigurationRuntimeException(cex);
    204            }
    205        }
    206
    207        if (defaultClass != null) {
    208            return defaultClass;
    209        }
    210
    211        final Class<?> clazz = factory.getDefaultBeanClass();
    212        if (clazz == null) {
    213            throw new ConfigurationRuntimeException("Bean class is not specified!");
    214        }
    215        return clazz;
    216    }
    217
    218    /**
    219     * Gets the Class of the property if it can be determined.
    220     *
    221     * @param bean The bean containing the property.
    222     * @param propName The name of the property.
    223     * @return The class associated with the property or null.
    224     */
    225    private static Class<?> getDefaultClass(final Object bean, final String propName) {
    226        try {
    227            final PropertyDescriptor desc = BEAN_UTILS_BEAN.getPropertyUtils().getPropertyDescriptor(bean, propName);
    228            if (desc == null) {
    229                return null;
    230            }
    231            return desc.getPropertyType();
    232        } catch (final Exception ex) {
    233            return null;
    234        }
    235    }
    236
    237    /**
    238     * Initializes the beans properties.
    239     *
    240     * @param bean the bean to be initialized
    241     * @param data the bean declaration
    242     * @throws ConfigurationRuntimeException if a property cannot be set
    243     */
    244    public static void initBeanProperties(final Object bean, final BeanDeclaration data) {
    245        final Map<String, Object> properties = data.getBeanProperties();
    246        if (properties != null) {
    247            properties.forEach((k, v) -> initProperty(bean, k, v));
    248        }
    249    }
    250
    251    /**
    252     * Initializes the shared {@code BeanUtilsBean} instance. This method sets up custom bean introspection in a way that
    253     * fluent parameter interfaces are supported.
    254     *
    255     * @return the {@code BeanUtilsBean} instance to be used for all property set operations
    256     */
    257    private static BeanUtilsBean initBeanUtilsBean() {
    258        final PropertyUtilsBean propUtilsBean = new PropertyUtilsBean();
    259        propUtilsBean.addBeanIntrospector(new FluentPropertyBeanIntrospector());
    260        return new BeanUtilsBean(new ConvertUtilsBean(), propUtilsBean);
    261    }
    262
    263    /**
    264     * Sets a property on the given bean using Common Beanutils.
    265     *
    266     * @param bean the bean
    267     * @param propName the name of the property
    268     * @param value the property's value
    269     * @throws ConfigurationRuntimeException if the property is not writable or an error occurred
    270     */
    271    private static void initProperty(final Object bean, final String propName, final Object value) {
    272        if (!isPropertyWriteable(bean, propName)) {
    273            throw new ConfigurationRuntimeException("Property " + propName + " cannot be set on " + bean.getClass().getName());
    274        }
    275
    276        try {
    277            BEAN_UTILS_BEAN.setProperty(bean, propName, value);
    278        } catch (final IllegalAccessException | InvocationTargetException itex) {
    279            throw new ConfigurationRuntimeException(itex);
    280        }
    281    }
    282
    283    /**
    284     * Tests whether the specified property of the given bean instance supports write access.
    285     *
    286     * @param bean the bean instance
    287     * @param propName the name of the property in question
    288     * @return <b>true</b> if this property can be written, <b>false</b> otherwise
    289     */
    290    private static boolean isPropertyWriteable(final Object bean, final String propName) {
    291        return BEAN_UTILS_BEAN.getPropertyUtils().isWriteable(bean, propName);
    292    }
    293
    294    /**
    295     * Loads a {@code Class} object for the specified name. Because class loading can be tricky in some
    296     * environments the code for retrieving a class by its name was extracted into this helper method. So if changes are
    297     * necessary, they can be made at a single place.
    298     *
    299     * @param name the name of the class to be loaded
    300     * @return the class object for the specified name
    301     * @throws ClassNotFoundException if the class cannot be loaded
    302     */
    303    static Class<?> loadClass(final String name) throws ClassNotFoundException {
    304        return ClassUtils.getClass(name);
    305    }
    306
    307    /**
    308     * Sets a property on the bean only if the property exists
    309     *
    310     * @param bean the bean
    311     * @param propName the name of the property
    312     * @param value the property's value
    313     * @throws ConfigurationRuntimeException if the property is not writable or an error occurred
    314     */
    315    public static void setProperty(final Object bean, final String propName, final Object value) {
    316        if (isPropertyWriteable(bean, propName)) {
    317            initProperty(bean, propName, value);
    318        }
    319    }
    320
    321    /** Stores a map with the registered bean factories. */
    322    private final Map<String, BeanFactory> beanFactories = Collections.synchronizedMap(new HashMap<>());
    323
    324    /**
    325     * Stores the default bean factory, which is used if no other factory is provided in a bean declaration.
    326     */
    327    private final BeanFactory defaultBeanFactory;
    328
    329    /**
    330     * Constructs a new instance of {@code BeanHelper} with the default instance of {@link DefaultBeanFactory} as default
    331     * {@link BeanFactory}.
    332     */
    333    public BeanHelper() {
    334        this(null);
    335    }
    336
    337    /**
    338     * Constructs a new instance of {@code BeanHelper} and sets the specified default {@code BeanFactory}.
    339     *
    340     * @param defaultBeanFactory the default {@code BeanFactory} (can be <b>null</b>, then a default instance is used)
    341     */
    342    public BeanHelper(final BeanFactory defaultBeanFactory) {
    343        this.defaultBeanFactory = defaultBeanFactory != null ? defaultBeanFactory : DefaultBeanFactory.INSTANCE;
    344    }
    345
    346    /**
    347     * Creates a bean instance for the specified declaration. This method is a short cut for
    348     * {@code createBean(data, null);}.
    349     *
    350     * @param data the bean declaration
    351     * @return the new bean
    352     * @throws ConfigurationRuntimeException if an error occurs
    353     */
    354    public Object createBean(final BeanDeclaration data) {
    355        return createBean(data, null);
    356    }
    357
    358    /**
    359     * Creates a bean instance for the specified declaration. This method is a short cut for
    360     * {@code createBean(data, null, null);}.
    361     *
    362     * @param data the bean declaration
    363     * @param defaultClass the class to be used when in the declaration no class is specified
    364     * @return the new bean
    365     * @throws ConfigurationRuntimeException if an error occurs
    366     */
    367    public Object createBean(final BeanDeclaration data, final Class<?> defaultClass) {
    368        return createBean(data, defaultClass, null);
    369    }
    370
    371    /**
    372     * The main method for creating and initializing beans from a configuration. This method will return an initialized
    373     * instance of the bean class specified in the passed in bean declaration. If this declaration does not contain the
    374     * class of the bean, the passed in default class will be used. From the bean declaration the factory to be used for
    375     * creating the bean is queried. The declaration may here return <b>null</b>, then a default factory is used. This
    376     * factory is then invoked to perform the create operation.
    377     *
    378     * @param data the bean declaration
    379     * @param defaultClass the default class to use
    380     * @param param an additional parameter that will be passed to the bean factory; some factories may support parameters
    381     *        and behave different depending on the value passed in here
    382     * @return the new bean
    383     * @throws ConfigurationRuntimeException if an error occurs
    384     */
    385    public Object createBean(final BeanDeclaration data, final Class<?> defaultClass, final Object param) {
    386        if (data == null) {
    387            throw new IllegalArgumentException("Bean declaration must not be null!");
    388        }
    389
    390        final BeanFactory factory = fetchBeanFactory(data);
    391        final BeanCreationContext bcc = createBeanCreationContext(data, defaultClass, param, factory);
    392        try {
    393            return factory.createBean(bcc);
    394        } catch (final Exception ex) {
    395            throw new ConfigurationRuntimeException(ex);
    396        }
    397    }
    398
    399    /**
    400     * Creates a {@code BeanCreationContext} object for the creation of the specified bean.
    401     *
    402     * @param data the bean declaration
    403     * @param defaultClass the default class to use
    404     * @param param an additional parameter that will be passed to the bean factory; some factories may support parameters
    405     *        and behave different depending on the value passed in here
    406     * @param factory the current bean factory
    407     * @return the {@code BeanCreationContext}
    408     * @throws ConfigurationRuntimeException if the bean class cannot be determined
    409     */
    410    private BeanCreationContext createBeanCreationContext(final BeanDeclaration data, final Class<?> defaultClass, final Object param,
    411        final BeanFactory factory) {
    412        final Class<?> beanClass = fetchBeanClass(data, defaultClass, factory);
    413        return new BeanCreationContextImpl(this, beanClass, data, param);
    414    }
    415
    416    /**
    417     * Deregisters the bean factory with the given name. After that this factory cannot be used any longer.
    418     *
    419     * @param name the name of the factory to be deregistered
    420     * @return the factory that was registered under this name; <b>null</b> if there was no such factory
    421     */
    422    public BeanFactory deregisterBeanFactory(final String name) {
    423        return beanFactories.remove(name);
    424    }
    425
    426    /**
    427     * Obtains the bean factory to use for creating the specified bean. This method will check whether a factory is
    428     * specified in the bean declaration. If this is not the case, the default bean factory will be used.
    429     *
    430     * @param data the bean declaration
    431     * @return the bean factory to use
    432     * @throws ConfigurationRuntimeException if the factory cannot be determined
    433     */
    434    private BeanFactory fetchBeanFactory(final BeanDeclaration data) {
    435        final String factoryName = data.getBeanFactoryName();
    436        if (factoryName != null) {
    437            final BeanFactory factory = beanFactories.get(factoryName);
    438            if (factory == null) {
    439                throw new ConfigurationRuntimeException("Unknown bean factory: " + factoryName);
    440            }
    441            return factory;
    442        }
    443        return getDefaultBeanFactory();
    444    }
    445
    446    /**
    447     * Gets the default bean factory.
    448     *
    449     * @return the default bean factory
    450     */
    451    public BeanFactory getDefaultBeanFactory() {
    452        return defaultBeanFactory;
    453    }
    454
    455    /**
    456     * Initializes the passed in bean. This method will obtain all the bean's properties that are defined in the passed in
    457     * bean declaration. These properties will be set on the bean. If necessary, further beans will be created recursively.
    458     *
    459     * @param bean the bean to be initialized
    460     * @param data the bean declaration
    461     * @throws ConfigurationRuntimeException if a property cannot be set
    462     */
    463    public void initBean(final Object bean, final BeanDeclaration data) {
    464        initBeanProperties(bean, data);
    465
    466        final Map<String, Object> nestedBeans = data.getNestedBeanDeclarations();
    467        if (nestedBeans != null) {
    468            if (bean instanceof Collection) {
    469                // This is safe because the collection stores the values of the
    470                // nested beans.
    471                @SuppressWarnings("unchecked")
    472                final Collection<Object> coll = (Collection<Object>) bean;
    473                if (nestedBeans.size() == 1) {
    474                    final Map.Entry<String, Object> e = nestedBeans.entrySet().iterator().next();
    475                    final String propName = e.getKey();
    476                    final Class<?> defaultClass = getDefaultClass(bean, propName);
    477                    if (e.getValue() instanceof List) {
    478                        // This is safe, provided that the bean declaration is implemented
    479                        // correctly.
    480                        @SuppressWarnings("unchecked")
    481                        final List<BeanDeclaration> decls = (List<BeanDeclaration>) e.getValue();
    482                        decls.forEach(decl -> coll.add(createBean(decl, defaultClass)));
    483                    } else {
    484                        coll.add(createBean((BeanDeclaration) e.getValue(), defaultClass));
    485                    }
    486                }
    487            } else {
    488                nestedBeans.forEach((propName, prop) -> {
    489                    final Class<?> defaultClass = getDefaultClass(bean, propName);
    490                    if (prop instanceof Collection) {
    491                        final Collection<Object> beanCollection = createPropertyCollection(propName, defaultClass);
    492                        ((Collection<BeanDeclaration>) prop).forEach(elemDef -> beanCollection.add(createBean(elemDef)));
    493                        initProperty(bean, propName, beanCollection);
    494                    } else {
    495                        initProperty(bean, propName, createBean((BeanDeclaration) prop, defaultClass));
    496                    }
    497                });
    498            }
    499        }
    500    }
    501
    502    /**
    503     * Registers a bean factory under a symbolic name. This factory object can then be specified in bean declarations with
    504     * the effect that this factory will be used to obtain an instance for the corresponding bean declaration.
    505     *
    506     * @param name the name of the factory
    507     * @param factory the factory to be registered
    508     */
    509    public void registerBeanFactory(final String name, final BeanFactory factory) {
    510        if (name == null) {
    511            throw new IllegalArgumentException("Name for bean factory must not be null!");
    512        }
    513        if (factory == null) {
    514            throw new IllegalArgumentException("Bean factory must not be null!");
    515        }
    516
    517        beanFactories.put(name, factory);
    518    }
    519
    520    /**
    521     * Gets a set with the names of all currently registered bean factories.
    522     *
    523     * @return a set with the names of the registered bean factories
    524     */
    525    public Set<String> registeredFactoryNames() {
    526        return beanFactories.keySet();
    527    }
    528}