    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.util.ArrayList;
    020import java.util.Collection;
    021import java.util.HashMap;
    022import java.util.LinkedList;
    023import java.util.List;
    024import java.util.Map;
    025import java.util.Set;
    026import java.util.function.Function;
    027import java.util.stream.Collectors;
    028
    029import org.apache.commons.configuration2.BaseHierarchicalConfiguration;
    030import org.apache.commons.configuration2.HierarchicalConfiguration;
    031import org.apache.commons.configuration2.ex.ConfigurationRuntimeException;
    032import org.apache.commons.configuration2.interpol.ConfigurationInterpolator;
    033import org.apache.commons.configuration2.tree.NodeHandler;
    034import org.apache.commons.lang3.StringUtils;
    035
    036/**
    037 * <p>
    038 * An implementation of the {@code BeanDeclaration} interface that is suitable for XML configuration files.
    039 * </p>
    040 * <p>
    041 * This class defines the standard layout of a bean declaration in an XML configuration file. Such a declaration must
    042 * look like the following example fragment:
    043 * </p>
    044 *
    045 * <pre>
    046 *   ...
    047 *   &lt;personBean config-class=&quot;my.model.PersonBean&quot;
    048 *       lastName=&quot;Doe&quot; firstName=&quot;John&quot;&gt;
    049 *       &lt;config-constrarg config-value=&quot;ID03493&quot; config-type=&quot;java.lang.String&quot;/&gt;
    050 *       &lt;address config-class=&quot;my.model.AddressBean&quot;
    051 *           street=&quot;21st street 11&quot; zip=&quot;1234&quot;
    052 *           city=&quot;TestCity&quot;/&gt;
    053 *   &lt;/personBean&gt;
    054 * </pre>
    055 *
    056 * <p>
    057 * The bean declaration can be contained in an arbitrary element. Here it is the {@code personBean} element. In the
    058 * attributes of this element there can occur some reserved attributes, which have the following meaning:
    059 * </p>
    060 * <dl>
    061 * <dt>{@code config-class}</dt>
    062 * <dd>Here the full qualified name of the bean's class can be specified. An instance of this class will be created. If
    063 * this attribute is not specified, the bean class must be provided in another way, e.g. as the {@code defaultClass}
    064 * passed to the {@code BeanHelper} class.</dd>
    065 * <dt>{@code config-factory}</dt>
    066 * <dd>This attribute can contain the name of the {@link BeanFactory} that should be used for creating the bean. If it
    067 * is defined, a factory with this name must have been registered at the {@code BeanHelper} class. If this attribute is
    068 * missing, the default bean factory will be used.</dd>
    069 * <dt>{@code config-factoryParam}</dt>
    070 * <dd>With this attribute a parameter can be specified that will be passed to the bean factory. This may be useful for
    071 * custom bean factories.</dd>
    072 * </dl>
    073 * <p>
    074 * All further attributes starting with the {@code config-} prefix are considered as meta data and will be ignored. All
    075 * other attributes are treated as properties of the bean to be created, i.e. corresponding setter methods of the bean
    076 * will be invoked with the values specified here.
    077 * </p>
    078 * <p>
    079 * If the bean to be created has also some complex properties (which are itself beans), their values cannot be
    080 * initialized from attributes. For this purpose nested elements can be used. The example listing shows how an address
    081 * bean can be initialized. This is done in a nested element whose name must match the name of a property of the
    082 * enclosing bean declaration. The format of this nested element is exactly the same as for the bean declaration itself,
    083 * i.e. it can have attributes defining meta data or bean properties and even further nested elements for complex bean
    084 * properties.
    085 * </p>
    086 * <p>
    087 * If the bean should be created using a specific constructor, the constructor arguments have to be specified. This is
    088 * done by an arbitrary number of nested {@code <config-constrarg>} elements. Each element can either have the
    089 * {@code config-value} attribute - then it defines a simple value - or must be again a bean declaration (conforming to
    090 * the format defined here) defining the complex value of this constructor argument.
    091 * </p>
    092 * <p>
    093 * A {@code XMLBeanDeclaration} object is usually created from a {@code HierarchicalConfiguration}. From this it will
    094 * derive a {@code SubnodeConfiguration}, which is used to access the needed properties. This subnode configuration can
    095 * be obtained using the {@link #getConfiguration()} method. All of its properties can be accessed in the usual way. To
    096 * ensure that the property keys used by this class are understood by the configuration, the default expression engine
    097 * will be set.
    098 * </p>
    099 *
    100 * @since 1.3
    101 */
    102public class XMLBeanDeclaration implements BeanDeclaration {
    103
    104    /** Constant for the prefix of reserved attributes. */
    105    public static final String RESERVED_PREFIX = "config-";
    106
    107    /** Constant for the prefix for reserved attributes. */
    108    public static final String ATTR_PREFIX = "[@" + RESERVED_PREFIX;
    109
    110    /** Constant for the bean class attribute. */
    111    public static final String ATTR_BEAN_CLASS = ATTR_PREFIX + "class]";
    112
    113    /** Constant for the bean factory attribute. */
    114    public static final String ATTR_BEAN_FACTORY = ATTR_PREFIX + "factory]";
    115
    116    /** Constant for the bean factory parameter attribute. */
    117    public static final String ATTR_FACTORY_PARAM = ATTR_PREFIX + "factoryParam]";
    118
    119    /** Constant for the name of the bean class attribute. */
    120    private static final String ATTR_BEAN_CLASS_NAME = RESERVED_PREFIX + "class";
    121
    122    /** Constant for the name of the element for constructor arguments. */
    123    private static final String ELEM_CTOR_ARG = RESERVED_PREFIX + "constrarg";
    124
    125    /**
    126     * Constant for the name of the attribute with the value of a constructor argument.
    127     */
    128    private static final String ATTR_CTOR_VALUE = RESERVED_PREFIX + "value";
    129
    130    /**
    131     * Constant for the name of the attribute with the data type of a constructor argument.
    132     */
    133    private static final String ATTR_CTOR_TYPE = RESERVED_PREFIX + "type";
    134
    135    /** Stores the associated configuration. */
    136    private final HierarchicalConfiguration<?> configuration;
    137
    138    /** Stores the configuration node that contains the bean declaration. */
    139    private final NodeData<?> nodeData;
    140
    141    /** The name of the default bean class. */
    142    private final String defaultBeanClassName;
    143
    144    /**
    145     * Constructs a new instance of {@code XMLBeanDeclaration} and initializes it from the given configuration. The passed in
    146     * key points to the bean declaration.
    147     *
    148     * @param config the configuration (must not be <b>null</b>)
    149     * @param key the key to the bean declaration (this key must point to exactly one bean declaration or a
    150     *        {@code IllegalArgumentException} exception will be thrown)
    151     * @param <T> the node type of the configuration
    152     * @throws IllegalArgumentException if required information is missing to construct the bean declaration
    153     */
    154    public <T> XMLBeanDeclaration(final HierarchicalConfiguration<T> config, final String key) {
    155        this(config, key, false);
    156    }
    157
    158    /**
    159     * Constructs a new instance of {@code XMLBeanDeclaration} and initializes it from the given configuration supporting
    160     * optional declarations.
    161     *
    162     * @param config the configuration (must not be <b>null</b>)
    163     * @param key the key to the bean declaration
    164     * @param optional a flag whether this declaration is optional; if set to <b>true</b>, no exception will be thrown if
    165     *        the passed in key is undefined
    166     * @param <T> the node type of the configuration
    167     * @throws IllegalArgumentException if required information is missing to construct the bean declaration
    168     */
    169    public <T> XMLBeanDeclaration(final HierarchicalConfiguration<T> config, final String key, final boolean optional) {
    170        this(config, key, optional, null);
    171    }
    172
    173    /**
    174     * Constructs a new instance of {@code XMLBeanDeclaration} and initializes it from the given configuration supporting
    175     * optional declarations and a default bean class name. The passed in key points to the bean declaration. If the key
    176     * does not exist and the boolean argument is <b>true</b>, the declaration is initialized with an empty configuration.
    177     * It is possible to create objects from such an empty declaration if a default class is provided. If the key on the
    178     * other hand has multiple values or is undefined and the boolean argument is <b>false</b>, a
    179     * {@code IllegalArgumentException} exception will be thrown. It is possible to set a default bean class name; this name
    180     * is used if the configuration does not contain a bean class.
    181     *
    182     * @param config the configuration (must not be <b>null</b>)
    183     * @param key the key to the bean declaration
    184     * @param optional a flag whether this declaration is optional; if set to <b>true</b>, no exception will be thrown if
    185     *        the passed in key is undefined
    186     * @param defBeanClsName a default bean class name
    187     * @param <T> the node type of the configuration
    188     * @throws IllegalArgumentException if required information is missing to construct the bean declaration
    189     * @since 2.0
    190     */
    191    public <T> XMLBeanDeclaration(final HierarchicalConfiguration<T> config, final String key, final boolean optional, final String defBeanClsName) {
    192        if (config == null) {
    193            throw new IllegalArgumentException("Configuration must not be null!");
    194        }
    195
    196        HierarchicalConfiguration<?> tmpconfiguration;
    197        try {
    198            tmpconfiguration = config.configurationAt(key);
    199        } catch (final ConfigurationRuntimeException iex) {
    200            // If we reach this block, the key does not have exactly one value
    201            if (!optional || config.getMaxIndex(key) > 0) {
    202                throw iex;
    203            }
    204            tmpconfiguration = new BaseHierarchicalConfiguration();
    205        }
    206        this.nodeData = createNodeDataFromConfiguration(tmpconfiguration);
    207        this.configuration = tmpconfiguration;
    208        defaultBeanClassName = defBeanClsName;
    209        initSubnodeConfiguration(getConfiguration());
    210    }
    211
    212    /**
    213     * Constructs a new instance of {@code XMLBeanDeclaration} and initializes it from the given configuration. The
    214     * configuration's root node must contain the bean declaration.
    215     *
    216     * @param config the configuration with the bean declaration
    217     * @param <T> the node type of the configuration
    218     */
    219    public <T> XMLBeanDeclaration(final HierarchicalConfiguration<T> config) {
    220        this(config, (String) null);
    221    }
    222
    223    /**
    224     * Constructs a new instance of {@code XMLBeanDeclaration} and initializes it with the configuration node that contains the
    225     * bean declaration. This constructor is used internally.
    226     *
    227     * @param config the configuration
    228     * @param node the node with the bean declaration.
    229     */
    230    XMLBeanDeclaration(final HierarchicalConfiguration<?> config, final NodeData<?> node) {
    231        this.nodeData = node;
    232        configuration = config;
    233        defaultBeanClassName = null;
    234        initSubnodeConfiguration(config);
    235    }
    236
    237    /**
    238     * Gets the configuration object this bean declaration is based on.
    239     *
    240     * @return the associated configuration
    241     */
    242    public HierarchicalConfiguration<?> getConfiguration() {
    243        return configuration;
    244    }
    245
    246    /**
    247     * Gets the name of the default bean class. This class is used if no bean class is specified in the configuration. It
    248     * may be <b>null</b> if no default class was set.
    249     *
    250     * @return the default bean class name
    251     * @since 2.0
    252     */
    253    public String getDefaultBeanClassName() {
    254        return defaultBeanClassName;
    255    }
    256
    257    /**
    258     * Gets the name of the bean factory. This information is fetched from the {@code config-factory} attribute.
    259     *
    260     * @return the name of the bean factory
    261     */
    262    @Override
    263    public String getBeanFactoryName() {
    264        return getConfiguration().getString(ATTR_BEAN_FACTORY, null);
    265    }
    266
    267    /**
    268     * Gets a parameter for the bean factory. This information is fetched from the {@code config-factoryParam} attribute.
    269     *
    270     * @return the parameter for the bean factory
    271     */
    272    @Override
    273    public Object getBeanFactoryParameter() {
    274        return getConfiguration().getProperty(ATTR_FACTORY_PARAM);
    275    }
    276
    277    /**
    278     * Gets the name of the class of the bean to be created. This information is obtained from the {@code config-class}
    279     * attribute.
    280     *
    281     * @return the name of the bean's class
    282     */
    283    @Override
    284    public String getBeanClassName() {
    285        return getConfiguration().getString(ATTR_BEAN_CLASS, getDefaultBeanClassName());
    286    }
    287
    288    /**
    289     * Gets a map with the bean's (simple) properties. The properties are collected from all attribute nodes, which are
    290     * not reserved.
    291     *
    292     * @return a map with the bean's properties
    293     */
    294    @Override
    295    public Map<String, Object> getBeanProperties() {
    296        return getAttributeNames().stream().filter(e -> !isReservedAttributeName(e))
    297            .collect(Collectors.toMap(Function.identity(), e -> interpolate(getNode().getAttribute(e))));
    298    }
    299
    300    /**
    301     * Gets a map with bean declarations for the complex properties of the bean to be created. These declarations are
    302     * obtained from the child nodes of this declaration's root node.
    303     *
    304     * @return a map with bean declarations for complex properties
    305     */
    306    @Override
    307    public Map<String, Object> getNestedBeanDeclarations() {
    308        final Map<String, Object> nested = new HashMap<>();
    309        getNode().getChildren().forEach(child -> {
    310            if (!isReservedChildName(child.nodeName())) {
    311                final Object obj = nested.get(child.nodeName());
    312                if (obj != null) {
    313                    final List<BeanDeclaration> list;
    314                    if (obj instanceof List) {
    315                        // Safe because we created the lists ourselves.
    316                        @SuppressWarnings("unchecked")
    317                        final List<BeanDeclaration> tmpList = (List<BeanDeclaration>) obj;
    318                        list = tmpList;
    319                    } else {
    320                        list = new ArrayList<>();
    321                        list.add((BeanDeclaration) obj);
    322                        nested.put(child.nodeName(), list);
    323                    }
    324                    list.add(createBeanDeclaration(child));
    325                } else {
    326                    nested.put(child.nodeName(), createBeanDeclaration(child));
    327                }
    328            }
    329        });
    330        return nested;
    331    }
    332
    333    /**
    334     * {@inheritDoc} This implementation processes all child nodes with the name {@code config-constrarg}. If such a node
    335     * has a {@code config-class} attribute, it is considered a nested bean declaration; otherwise it is interpreted as a
    336     * simple value. If no nested constructor argument declarations are found, result is an empty collection.
    337     */
    338    @Override
    339    public Collection<ConstructorArg> getConstructorArgs() {
    340        return getNode().getChildren(ELEM_CTOR_ARG).stream().map(this::createConstructorArg).collect(Collectors.toCollection(LinkedList::new));
    341    }
    342
    343    /**
    344     * Performs interpolation for the specified value. This implementation will interpolate against the current subnode
    345     * configuration's parent. If sub classes need a different interpolation mechanism, they should override this method.
    346     *
    347     * @param value the value that is to be interpolated
    348     * @return the interpolated value
    349     */
    350    protected Object interpolate(final Object value) {
    351        final ConfigurationInterpolator interpolator = getConfiguration().getInterpolator();
    352        return interpolator != null ? interpolator.interpolate(value) : value;
    353    }
    354
    355    /**
    356     * Tests if the specified child node name is reserved and thus should be ignored. This method is called when processing
    357     * child nodes of this bean declaration. It is then possible to ignore some nodes with a specific meaning. This
    358     * implementation delegates to {@link #isReservedName(String)} .
    359     *
    360     * @param name the name of the child node to be checked
    361     * @return a flag whether this name is reserved
    362     * @since 2.0
    363     */
    364    protected boolean isReservedChildName(final String name) {
    365        return isReservedName(name);
    366    }
    367
    368    /**
    369     * Tests if the specified attribute name is reserved and thus does not point to a property of the bean to be created.
    370     * This method is called when processing the attributes of this bean declaration. It is then possible to ignore some
    371     * attributes with a specific meaning. This implementation delegates to {@link #isReservedName(String)}.
    372     *
    373     * @param name the name of the attribute to be checked
    374     * @return a flag whether this name is reserved
    375     * @since 2.0
    376     */
    377    protected boolean isReservedAttributeName(final String name) {
    378        return isReservedName(name);
    379    }
    380
    381    /**
    382     * Tests if the specified name of a node or attribute is reserved and thus should be ignored. This method is called per
    383     * default by the methods for checking attribute and child node names. It checks whether the passed in name starts with
    384     * the reserved prefix.
    385     *
    386     * @param name the name to be checked
    387     * @return a flag whether this name is reserved
    388     */
    389    protected boolean isReservedName(final String name) {
    390        return name == null || name.startsWith(RESERVED_PREFIX);
    391    }
    392
    393    /**
    394     * Gets a set with the names of the attributes of the configuration node holding the data of this bean declaration.
    395     *
    396     * @return the attribute names of the underlying configuration node
    397     */
    398    protected Set<String> getAttributeNames() {
    399        return getNode().getAttributes();
    400    }
    401
    402    /**
    403     * Gets the data about the associated node.
    404     *
    405     * @return the node with the bean declaration
    406     */
    407    NodeData<?> getNode() {
    408        return nodeData;
    409    }
    410
    411    /**
    412     * Creates a new {@code BeanDeclaration} for a child node of the current configuration node. This method is called by
    413     * {@code getNestedBeanDeclarations()} for all complex sub properties detected by this method. Derived classes can hook
    414     * in if they need a specific initialization. This base implementation creates a {@code XMLBeanDeclaration} that is
    415     * properly initialized from the passed in node.
    416     *
    417     * @param nodeData the child node, for which a {@code BeanDeclaration} is to be created
    418     * @return the {@code BeanDeclaration} for this child node
    419     */
    420    BeanDeclaration createBeanDeclaration(final NodeData<?> nodeData) {
    421        for (final HierarchicalConfiguration<?> config : getConfiguration().configurationsAt(nodeData.escapedNodeName(getConfiguration()))) {
    422            if (nodeData.matchesConfigRootNode(config)) {
    423                return new XMLBeanDeclaration(config, nodeData);
    424            }
    425        }
    426        throw new ConfigurationRuntimeException("Unable to match node for " + nodeData.nodeName());
    427    }
    428
    429    /**
    430     * Initializes the internally managed sub configuration. This method will set some default values for some properties.
    431     *
    432     * @param conf the configuration to initialize
    433     */
    434    private void initSubnodeConfiguration(final HierarchicalConfiguration<?> conf) {
    435        conf.setExpressionEngine(null);
    436    }
    437
    438    /**
    439     * Creates a {@code ConstructorArg} object for the specified configuration node.
    440     *
    441     * @param child the configuration node
    442     * @return the corresponding {@code ConstructorArg} object
    443     */
    444    private ConstructorArg createConstructorArg(final NodeData<?> child) {
    445        final String type = getAttribute(child, ATTR_CTOR_TYPE);
    446        if (isBeanDeclarationArgument(child)) {
    447            return ConstructorArg.forValue(getAttribute(child, ATTR_CTOR_VALUE), type);
    448        }
    449        return ConstructorArg.forBeanDeclaration(createBeanDeclaration(child), type);
    450    }
    451
    452    /**
    453     * Gets an attribute of a configuration node. This method also takes interpolation into account.
    454     *
    455     * @param nodeData the node
    456     * @param attribute the name of the attribute
    457     * @return the string value of this attribute (can be <b>null</b>)
    458     */
    459    private String getAttribute(final NodeData<?> nodeData, final String attribute) {
    460        final Object value = nodeData.getAttribute(attribute);
    461        return value == null ? null : String.valueOf(interpolate(value));
    462    }
    463
    464    /**
    465     * Tests whether the constructor argument represented by the given configuration node is a bean declaration.
    466     *
    467     * @param nodeData the configuration node in question
    468     * @return a flag whether this constructor argument is a bean declaration
    469     */
    470    private static boolean isBeanDeclarationArgument(final NodeData<?> nodeData) {
    471        return !nodeData.getAttributes().contains(ATTR_BEAN_CLASS_NAME);
    472    }
    473
    474    /**
    475     * Creates a {@code NodeData} object from the root node of the given configuration.
    476     *
    477     * @param config the configuration
    478     * @param <T> the type of the nodes
    479     * @return the {@code NodeData} object
    480     */
    481    private static <T> NodeData<T> createNodeDataFromConfiguration(final HierarchicalConfiguration<T> config) {
    482        final NodeHandler<T> handler = config.getNodeModel().getNodeHandler();
    483        return new NodeData<>(handler.getRootNode(), handler);
    484    }
    485
    486    /**
    487     * An internal helper class which wraps the node with the bean declaration and the corresponding node handler.
    488     *
    489     * @param <T> the type of the node
    490     */
    491    static class NodeData<T> {
    492
    493        /** The wrapped node. */
    494        private final T node;
    495
    496        /** The node handler for interacting with this node. */
    497        private final NodeHandler<T> nodeHandler;
    498
    499        /**
    500         * Constructs a new instance of {@code NodeData}.
    501         *
    502         * @param node the node
    503         * @param nodeHandler the node handler
    504         */
    505        NodeData(final T node, final NodeHandler<T> nodeHandler) {
    506            this.node = node;
    507            this.nodeHandler = nodeHandler;
    508        }
    509
    510        /**
    511         * Returns the name of the wrapped node.
    512         *
    513         * @return the node name
    514         */
    515        String nodeName() {
    516            return nodeHandler.nodeName(node);
    517        }
    518
    519        /**
    520         * Returns the unescaped name of the node stored in this data object. This method handles the case that the node name
    521         * may contain reserved characters with a special meaning for the current expression engine. In this case, the
    522         * characters affected have to be escaped accordingly.
    523         *
    524         * @param config the configuration
    525         * @return the escaped node name
    526         */
    527        String escapedNodeName(final HierarchicalConfiguration<?> config) {
    528            return config.getExpressionEngine().nodeKey(node, StringUtils.EMPTY, nodeHandler);
    529        }
    530
    531        /**
    532         * Gets a list with the children of the wrapped node, again wrapped into {@code NodeData} objects.
    533         *
    534         * @return a list with the children
    535         */
    536        List<NodeData<T>> getChildren() {
    537            return wrapInNodeData(nodeHandler.getChildren(node));
    538        }
    539
    540        /**
    541         * Gets a list with the children of the wrapped node with the given name, again wrapped into {@code NodeData}
    542         * objects.
    543         *
    544         * @param name the name of the desired child nodes
    545         * @return a list with the children with this name
    546         */
    547        List<NodeData<T>> getChildren(final String name) {
    548            return wrapInNodeData(nodeHandler.getChildren(node, name));
    549        }
    550
    551        /**
    552         * Gets a set with the names of the attributes of the wrapped node.
    553         *
    554         * @return the attribute names of this node
    555         */
    556        Set<String> getAttributes() {
    557            return nodeHandler.getAttributes(node);
    558        }
    559
    560        /**
    561         * Gets the value of the attribute with the given name of the wrapped node.
    562         *
    563         * @param key the key of the attribute
    564         * @return the value of this attribute
    565         */
    566        Object getAttribute(final String key) {
    567            return nodeHandler.getAttributeValue(node, key);
    568        }
    569
    570        /**
    571         * Returns a flag whether the wrapped node is the root node of the passed in configuration.
    572         *
    573         * @param config the configuration
    574         * @return a flag whether this node is the configuration's root node
    575         */
    576        boolean matchesConfigRootNode(final HierarchicalConfiguration<?> config) {
    577            return config.getNodeModel().getNodeHandler().getRootNode().equals(node);
    578        }
    579
    580        /**
    581         * Wraps the passed in list of nodes in {@code NodeData} objects.
    582         *
    583         * @param nodes the list with nodes
    584         * @return the wrapped nodes
    585         */
    586        List<NodeData<T>> wrapInNodeData(final List<T> nodes) {
    587            return nodes.stream().map(n -> new NodeData<>(n, nodeHandler)).collect(Collectors.toList());
    588        }
    589    }
    590}