    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
    018package org.apache.commons.configuration2;
    019
    020import javax.xml.parsers.DocumentBuilder;
    021import javax.xml.parsers.DocumentBuilderFactory;
    022import javax.xml.parsers.ParserConfigurationException;
    023import javax.xml.transform.OutputKeys;
    024import javax.xml.transform.Result;
    025import javax.xml.transform.Source;
    026import javax.xml.transform.Transformer;
    027import javax.xml.transform.dom.DOMSource;
    028import javax.xml.transform.stream.StreamResult;
    029import java.io.IOException;
    030import java.io.InputStream;
    031import java.io.Reader;
    032import java.io.StringReader;
    033import java.io.StringWriter;
    034import java.io.Writer;
    035import java.net.URL;
    036import java.util.ArrayList;
    037import java.util.Collection;
    038import java.util.Collections;
    039import java.util.HashMap;
    040import java.util.Iterator;
    041import java.util.Map;
    042
    043import org.apache.commons.configuration2.convert.ListDelimiterHandler;
    044import org.apache.commons.configuration2.ex.ConfigurationException;
    045import org.apache.commons.configuration2.io.ConfigurationLogger;
    046import org.apache.commons.configuration2.io.FileLocator;
    047import org.apache.commons.configuration2.io.FileLocatorAware;
    048import org.apache.commons.configuration2.io.InputStreamSupport;
    049import org.apache.commons.configuration2.resolver.DefaultEntityResolver;
    050import org.apache.commons.configuration2.tree.ImmutableNode;
    051import org.apache.commons.configuration2.tree.NodeTreeWalker;
    052import org.apache.commons.configuration2.tree.ReferenceNodeHandler;
    053import org.apache.commons.lang3.StringUtils;
    054import org.apache.commons.lang3.mutable.MutableObject;
    055import org.w3c.dom.Attr;
    056import org.w3c.dom.CDATASection;
    057import org.w3c.dom.Document;
    058import org.w3c.dom.Element;
    059import org.w3c.dom.NamedNodeMap;
    060import org.w3c.dom.Node;
    061import org.w3c.dom.NodeList;
    062import org.w3c.dom.Text;
    063import org.xml.sax.EntityResolver;
    064import org.xml.sax.InputSource;
    065import org.xml.sax.SAXException;
    066import org.xml.sax.SAXParseException;
    067import org.xml.sax.helpers.DefaultHandler;
    068
    069/**
    070 * <p>
    071 * A specialized hierarchical configuration class that is able to parse XML
    072 * documents.
    073 * </p>
    074 * <p>
    075 * The parsed document will be stored keeping its structure. The class also
    076 * tries to preserve as much information from the loaded XML document as
    077 * possible, including comments and processing instructions. These will be
    078 * contained in documents created by the {@code save()} methods, too.
    079 * </p>
    080 * <p>
    081 * Like other file based configuration classes this class maintains the name and
    082 * path to the loaded configuration file. These properties can be altered using
    083 * several setter methods, but they are not modified by {@code save()} and
    084 * {@code load()} methods. If XML documents contain relative paths to other
    085 * documents (e.g. to a DTD), these references are resolved based on the path
    086 * set for this configuration.
    087 * </p>
    088 * <p>
    089 * By inheriting from {@link AbstractConfiguration} this class provides some
    090 * extended functionality, e.g. interpolation of property values. Like in
    091 * {@link PropertiesConfiguration} property values can contain delimiter
    092 * characters (the comma ',' per default) and are then split into multiple
    093 * values. This works for XML attributes and text content of elements as well.
    094 * The delimiter can be escaped by a backslash. As an example consider the
    095 * following XML fragment:
    096 * </p>
    097 *
    098 * <pre>
    099 * &lt;config&gt;
    100 *   &lt;array&gt;10,20,30,40&lt;/array&gt;
    101 *   &lt;scalar&gt;3\,1415&lt;/scalar&gt;
    102 *   &lt;cite text="To be or not to be\, this is the question!"/&gt;
    103 * &lt;/config&gt;
    104 * </pre>
    105 *
    106 * <p>
    107 * Here the content of the {@code array} element will be split at the commas, so
    108 * the {@code array} key will be assigned 4 values. In the {@code scalar}
    109 * property and the {@code text} attribute of the {@code cite} element the comma
    110 * is escaped, so that no splitting is performed.
    111 * </p>
    112 * <p>
    113 * The configuration API allows setting multiple values for a single attribute,
    114 * e.g. something like the following is legal (assuming that the default
    115 * expression engine is used):
    116 * </p>
    117 *
    118 * <pre>
    119 * XMLConfiguration config = new XMLConfiguration();
    120 * config.addProperty(&quot;test.dir[@name]&quot;, &quot;C:\\Temp\\&quot;);
    121 * config.addProperty(&quot;test.dir[@name]&quot;, &quot;D:\\Data\\&quot;);
    122 * </pre>
    123 *
    124 * <p>
    125 * However, in XML such a constellation is not supported; an attribute can
    126 * appear only once for a single element. Therefore, an attempt to save a
    127 * configuration which violates this condition will throw an exception.
    128 * </p>
    129 * <p>
    130 * Like other {@code Configuration} implementations, {@code XMLConfiguration}
    131 * uses a {@link ListDelimiterHandler} object for controlling list split
    132 * operations. Per default, a list delimiter handler object is set which
    133 * disables this feature. XML has a built-in support for complex structures
    134 * including list properties; therefore, list splitting is not that relevant for
    135 * this configuration type. Nevertheless, by setting an alternative
    136 * {@code ListDelimiterHandler} implementation, this feature can be enabled. It
    137 * works as for any other concrete {@code Configuration} implementation.
    138 * </p>
    139 * <p>
    140 * Whitespace in the content of XML documents is trimmed per default. In most
    141 * cases this is desired. However, sometimes whitespace is indeed important and
    142 * should be treated as part of the value of a property as in the following
    143 * example:
    144 * </p>
    145 * <pre>
    146 *   &lt;indent&gt;    &lt;/indent&gt;
    147 * </pre>
    148 *
    149 * <p>
    150 * Per default the spaces in the {@code indent} element will be trimmed
    151 * resulting in an empty element. To tell {@code XMLConfiguration} that spaces
    152 * are relevant the {@code xml:space} attribute can be used, which is defined in
    153 * the <a href="http://www.w3.org/TR/REC-xml/#sec-white-space">XML
    154 * specification</a>. This will look as follows:
    155 * </p>
    156 * <pre>
    157 *   &lt;indent <strong>xml:space=&quot;preserve&quot;</strong>&gt;    &lt;/indent&gt;
    158 * </pre>
    159 *
    160 * <p>
    161 * The value of the {@code indent} property will now contain the spaces.
    162 * </p>
    163 * <p>
    164 * {@code XMLConfiguration} implements the {@link FileBasedConfiguration}
    165 * interface and thus can be used together with a file-based builder to load XML
    166 * configuration files from various sources like files, URLs, or streams.
    167 * </p>
    168 * <p>
    169 * Like other {@code Configuration} implementations, this class uses a
    170 * {@code Synchronizer} object to control concurrent access. By choosing a
    171 * suitable implementation of the {@code Synchronizer} interface, an instance
    172 * can be made thread-safe or not. Note that access to most of the properties
    173 * typically set through a builder is not protected by the {@code Synchronizer}.
    174 * The intended usage is that these properties are set once at construction time
    175 * through the builder and after that remain constant. If you wish to change
    176 * such properties during life time of an instance, you have to use the
    177 * {@code lock()} and {@code unlock()} methods manually to ensure that other
    178 * threads see your changes.
    179 * </p>
    180 * <p>
    181 * More information about the basic functionality supported by
    182 * {@code XMLConfiguration} can be found at the user's guide at
    183 * <a href="http://commons.apache.org/proper/commons-configuration/userguide/howto_basicfeatures.html">
    184 * Basic features and AbstractConfiguration</a>. There is
    185 * also a separate chapter dealing with
    186 * <a href="commons.apache.org/proper/commons-configuration/userguide/howto_xml.html">
    187 * XML Configurations</a> in special.
    188 * </p>
    189 *
    190 * @since commons-configuration 1.0
    191 * @author J&ouml;rg Schaible
    192 */
    193public class XMLConfiguration extends BaseHierarchicalConfiguration implements
    194        FileBasedConfiguration, FileLocatorAware, InputStreamSupport
    195{
    196    /** Constant for the default root element name. */
    197    private static final String DEFAULT_ROOT_NAME = "configuration";
    198
    199    /** Constant for the name of the space attribute.*/
    200    private static final String ATTR_SPACE = "xml:space";
    201
    202    /** Constant for an internally used space attribute. */
    203    private static final String ATTR_SPACE_INTERNAL = "config-xml:space";
    204
    205    /** Constant for the xml:space value for preserving whitespace.*/
    206    private static final String VALUE_PRESERVE = "preserve";
    207
    208    /** Schema Langauge key for the parser */
    209    private static final String JAXP_SCHEMA_LANGUAGE =
    210        "http://java.sun.com/xml/jaxp/properties/schemaLanguage";
    211
    212    /** Schema Language for the parser */
    213    private static final String W3C_XML_SCHEMA =
    214        "http://www.w3.org/2001/XMLSchema";
    215
    216    /** Stores the name of the root element. */
    217    private String rootElementName;
    218
    219    /** Stores the public ID from the DOCTYPE.*/
    220    private String publicID;
    221
    222    /** Stores the system ID from the DOCTYPE.*/
    223    private String systemID;
    224
    225    /** Stores the document builder that should be used for loading.*/
    226    private DocumentBuilder documentBuilder;
    227
    228    /** Stores a flag whether DTD or Schema validation should be performed.*/
    229    private boolean validating;
    230
    231    /** Stores a flag whether DTD or Schema validation is used */
    232    private boolean schemaValidation;
    233
    234    /** The EntityResolver to use */
    235    private EntityResolver entityResolver = new DefaultEntityResolver();
    236
    237    /** The current file locator. */
    238    private FileLocator locator;
    239
    240    /**
    241     * Creates a new instance of {@code XMLConfiguration}.
    242     */
    243    public XMLConfiguration()
    244    {
    245        super();
    246        initLogger(new ConfigurationLogger(XMLConfiguration.class));
    247    }
    248
    249    /**
    250     * Creates a new instance of {@code XMLConfiguration} and copies the
    251     * content of the passed in configuration into this object. Note that only
    252     * the data of the passed in configuration will be copied. If, for instance,
    253     * the other configuration is a {@code XMLConfiguration}, too,
    254     * things like comments or processing instructions will be lost.
    255     *
    256     * @param c the configuration to copy
    257     * @since 1.4
    258     */
    259    public XMLConfiguration(final HierarchicalConfiguration<ImmutableNode> c)
    260    {
    261        super(c);
    262        rootElementName =
    263                (c != null) ? c.getRootElementName() : null;
    264        initLogger(new ConfigurationLogger(XMLConfiguration.class));
    265    }
    266
    267    /**
    268     * Returns the name of the root element. If this configuration was loaded
    269     * from a XML document, the name of this document's root element is
    270     * returned. Otherwise it is possible to set a name for the root element
    271     * that will be used when this configuration is stored.
    272     *
    273     * @return the name of the root element
    274     */
    275    @Override
    276    protected String getRootElementNameInternal()
    277    {
    278        final Document doc = getDocument();
    279        if (doc == null)
    280        {
    281            return (rootElementName == null) ? DEFAULT_ROOT_NAME : rootElementName;
    282        }
    283        return doc.getDocumentElement().getNodeName();
    284    }
    285
    286    /**
    287     * Sets the name of the root element. This name is used when this
    288     * configuration object is stored in an XML file. Note that setting the name
    289     * of the root element works only if this configuration has been newly
    290     * created. If the configuration was loaded from an XML file, the name
    291     * cannot be changed and an {@code UnsupportedOperationException}
    292     * exception is thrown. Whether this configuration has been loaded from an
    293     * XML document or not can be found out using the {@code getDocument()}
    294     * method.
    295     *
    296     * @param name the name of the root element
    297     */
    298    public void setRootElementName(final String name)
    299    {
    300        beginRead(true);
    301        try
    302        {
    303            if (getDocument() != null)
    304            {
    305                throw new UnsupportedOperationException(
    306                        "The name of the root element "
    307                                + "cannot be changed when loaded from an XML document!");
    308            }
    309            rootElementName = name;
    310        }
    311        finally
    312        {
    313            endRead();
    314        }
    315    }
    316
    317    /**
    318     * Returns the {@code DocumentBuilder} object that is used for
    319     * loading documents. If no specific builder has been set, this method
    320     * returns <b>null</b>.
    321     *
    322     * @return the {@code DocumentBuilder} for loading new documents
    323     * @since 1.2
    324     */
    325    public DocumentBuilder getDocumentBuilder()
    326    {
    327        return documentBuilder;
    328    }
    329
    330    /**
    331     * Sets the {@code DocumentBuilder} object to be used for loading
    332     * documents. This method makes it possible to specify the exact document
    333     * builder. So an application can create a builder, configure it for its
    334     * special needs, and then pass it to this method.
    335     *
    336     * @param documentBuilder the document builder to be used; if undefined, a
    337     * default builder will be used
    338     * @since 1.2
    339     */
    340    public void setDocumentBuilder(final DocumentBuilder documentBuilder)
    341    {
    342        this.documentBuilder = documentBuilder;
    343    }
    344
    345    /**
    346     * Returns the public ID of the DOCTYPE declaration from the loaded XML
    347     * document. This is <b>null</b> if no document has been loaded yet or if
    348     * the document does not contain a DOCTYPE declaration with a public ID.
    349     *
    350     * @return the public ID
    351     * @since 1.3
    352     */
    353    public String getPublicID()
    354    {
    355        beginRead(false);
    356        try
    357        {
    358            return publicID;
    359        }
    360        finally
    361        {
    362            endRead();
    363        }
    364    }
    365
    366    /**
    367     * Sets the public ID of the DOCTYPE declaration. When this configuration is
    368     * saved, a DOCTYPE declaration will be constructed that contains this
    369     * public ID.
    370     *
    371     * @param publicID the public ID
    372     * @since 1.3
    373     */
    374    public void setPublicID(final String publicID)
    375    {
    376        beginWrite(false);
    377        try
    378        {
    379            this.publicID = publicID;
    380        }
    381        finally
    382        {
    383            endWrite();
    384        }
    385    }
    386
    387    /**
    388     * Returns the system ID of the DOCTYPE declaration from the loaded XML
    389     * document. This is <b>null</b> if no document has been loaded yet or if
    390     * the document does not contain a DOCTYPE declaration with a system ID.
    391     *
    392     * @return the system ID
    393     * @since 1.3
    394     */
    395    public String getSystemID()
    396    {
    397        beginRead(false);
    398        try
    399        {
    400            return systemID;
    401        }
    402        finally
    403        {
    404            endRead();
    405        }
    406    }
    407
    408    /**
    409     * Sets the system ID of the DOCTYPE declaration. When this configuration is
    410     * saved, a DOCTYPE declaration will be constructed that contains this
    411     * system ID.
    412     *
    413     * @param systemID the system ID
    414     * @since 1.3
    415     */
    416    public void setSystemID(final String systemID)
    417    {
    418        beginWrite(false);
    419        try
    420        {
    421            this.systemID = systemID;
    422        }
    423        finally
    424        {
    425            endWrite();
    426        }
    427    }
    428
    429    /**
    430     * Returns the value of the validating flag.
    431     *
    432     * @return the validating flag
    433     * @since 1.2
    434     */
    435    public boolean isValidating()
    436    {
    437        return validating;
    438    }
    439
    440    /**
    441     * Sets the value of the validating flag. This flag determines whether
    442     * DTD/Schema validation should be performed when loading XML documents. This
    443     * flag is evaluated only if no custom {@code DocumentBuilder} was set.
    444     *
    445     * @param validating the validating flag
    446     * @since 1.2
    447     */
    448    public void setValidating(final boolean validating)
    449    {
    450        if (!schemaValidation)
    451        {
    452            this.validating = validating;
    453        }
    454    }
    455
    456
    457    /**
    458     * Returns the value of the schemaValidation flag.
    459     *
    460     * @return the schemaValidation flag
    461     * @since 1.7
    462     */
    463    public boolean isSchemaValidation()
    464    {
    465        return schemaValidation;
    466    }
    467
    468    /**
    469     * Sets the value of the schemaValidation flag. This flag determines whether
    470     * DTD or Schema validation should be used. This
    471     * flag is evaluated only if no custom {@code DocumentBuilder} was set.
    472     * If set to true the XML document must contain a schemaLocation definition
    473     * that provides resolvable hints to the required schemas.
    474     *
    475     * @param schemaValidation the validating flag
    476     * @since 1.7
    477     */
    478    public void setSchemaValidation(final boolean schemaValidation)
    479    {
    480        this.schemaValidation = schemaValidation;
    481        if (schemaValidation)
    482        {
    483            this.validating = true;
    484        }
    485    }
    486
    487    /**
    488     * Sets a new EntityResolver. Setting this will cause RegisterEntityId to have no
    489     * effect.
    490     * @param resolver The EntityResolver to use.
    491     * @since 1.7
    492     */
    493    public void setEntityResolver(final EntityResolver resolver)
    494    {
    495        this.entityResolver = resolver;
    496    }
    497
    498    /**
    499     * Returns the EntityResolver.
    500     * @return The EntityResolver.
    501     * @since 1.7
    502     */
    503    public EntityResolver getEntityResolver()
    504    {
    505        return this.entityResolver;
    506    }
    507
    508    /**
    509     * Returns the XML document this configuration was loaded from. The return
    510     * value is <b>null</b> if this configuration was not loaded from a XML
    511     * document.
    512     *
    513     * @return the XML document this configuration was loaded from
    514     */
    515    public Document getDocument()
    516    {
    517        final XMLDocumentHelper docHelper = getDocumentHelper();
    518        return (docHelper != null) ? docHelper.getDocument() : null;
    519    }
    520
    521    /**
    522     * Returns the helper object for managing the underlying document.
    523     *
    524     * @return the {@code XMLDocumentHelper}
    525     */
    526    private XMLDocumentHelper getDocumentHelper()
    527    {
    528        final ReferenceNodeHandler handler = getReferenceHandler();
    529        return (XMLDocumentHelper) handler.getReference(handler.getRootNode());
    530    }
    531
    532    /**
    533     * Returns the extended node handler with support for references.
    534     *
    535     * @return the {@code ReferenceNodeHandler}
    536     */
    537    private ReferenceNodeHandler getReferenceHandler()
    538    {
    539        return getSubConfigurationParentModel().getReferenceNodeHandler();
    540    }
    541
    542    /**
    543     * Initializes this configuration from an XML document.
    544     *
    545     * @param docHelper the helper object with the document to be parsed
    546     * @param elemRefs a flag whether references to the XML elements should be set
    547     */
    548    private void initProperties(final XMLDocumentHelper docHelper, final boolean elemRefs)
    549    {
    550        final Document document = docHelper.getDocument();
    551        setPublicID(docHelper.getSourcePublicID());
    552        setSystemID(docHelper.getSourceSystemID());
    553
    554        final ImmutableNode.Builder rootBuilder = new ImmutableNode.Builder();
    555        final MutableObject<String> rootValue = new MutableObject<>();
    556        final Map<ImmutableNode, Object> elemRefMap =
    557                elemRefs ? new HashMap<>() : null;
    558        final Map<String, String> attributes =
    559                constructHierarchy(rootBuilder, rootValue,
    560                        document.getDocumentElement(), elemRefMap, true, 0);
    561        attributes.remove(ATTR_SPACE_INTERNAL);
    562        final ImmutableNode top =
    563                rootBuilder.value(rootValue.getValue())
    564                        .addAttributes(attributes).create();
    565        getSubConfigurationParentModel().mergeRoot(top,
    566                document.getDocumentElement().getTagName(), elemRefMap,
    567                elemRefs ? docHelper : null, this);
    568    }
    569
    570    /**
    571     * Helper method for building the internal storage hierarchy. The XML
    572     * elements are transformed into node objects.
    573     *
    574     * @param node a builder for the current node
    575     * @param refValue stores the text value of the element
    576     * @param element the current XML element
    577     * @param elemRefs a map for assigning references objects to nodes; can be
    578     *        <b>null</b>, then reference objects are irrelevant
    579     * @param trim a flag whether the text content of elements should be
    580     *        trimmed; this controls the whitespace handling
    581     * @param level the current level in the hierarchy
    582     * @return a map with all attribute values extracted for the current node;
    583     *         this map also contains the value of the trim flag for this node
    584     *         under the key {@value #ATTR_SPACE}
    585     */
    586    private Map<String, String> constructHierarchy(final ImmutableNode.Builder node,
    587            final MutableObject<String> refValue, final Element element,
    588            final Map<ImmutableNode, Object> elemRefs, final boolean trim, final int level)
    589    {
    590        final boolean trimFlag = shouldTrim(element, trim);
    591        final Map<String, String> attributes = processAttributes(element);
    592        attributes.put(ATTR_SPACE_INTERNAL, String.valueOf(trimFlag));
    593        final StringBuilder buffer = new StringBuilder();
    594        final NodeList list = element.getChildNodes();
    595        boolean hasChildren = false;
    596
    597        for (int i = 0; i < list.getLength(); i++)
    598        {
    599            final org.w3c.dom.Node w3cNode = list.item(i);
    600            if (w3cNode instanceof Element)
    601            {
    602                final Element child = (Element) w3cNode;
    603                final ImmutableNode.Builder childNode = new ImmutableNode.Builder();
    604                childNode.name(child.getTagName());
    605                final MutableObject<String> refChildValue =
    606                        new MutableObject<>();
    607                final Map<String, String> attrmap =
    608                        constructHierarchy(childNode, refChildValue, child,
    609                                elemRefs, trimFlag, level + 1);
    610                final Boolean childTrim = Boolean.valueOf(attrmap.remove(ATTR_SPACE_INTERNAL));
    611                childNode.addAttributes(attrmap);
    612                final ImmutableNode newChild =
    613                        createChildNodeWithValue(node, childNode, child,
    614                                refChildValue.getValue(),
    615                                childTrim.booleanValue(), attrmap, elemRefs);
    616                if (elemRefs != null && !elemRefs.containsKey(newChild))
    617                {
    618                    elemRefs.put(newChild, child);
    619                }
    620                hasChildren = true;
    621            }
    622            else if (w3cNode instanceof Text)
    623            {
    624                final Text data = (Text) w3cNode;
    625                buffer.append(data.getData());
    626            }
    627        }
    628
    629        boolean childrenFlag = false;
    630        if (hasChildren || trimFlag)
    631        {
    632            childrenFlag = hasChildren || attributes.size() > 1;
    633        }
    634        final String text = determineValue(buffer.toString(), childrenFlag, trimFlag);
    635        if (text.length() > 0 || (!childrenFlag && level != 0))
    636        {
    637            refValue.setValue(text);
    638        }
    639        return attributes;
    640    }
    641
    642    /**
    643     * Determines the value of a configuration node. This method mainly checks
    644     * whether the text value is to be trimmed or not. This is normally defined
    645     * by the trim flag. However, if the node has children and its content is
    646     * only whitespace, then it makes no sense to store any value; this would
    647     * only scramble layout when the configuration is saved again.
    648     *
    649     * @param content the text content of this node
    650     * @param hasChildren a flag whether the node has children
    651     * @param trimFlag the trim flag
    652     * @return the value to be stored for this node
    653     */
    654    private static String determineValue(final String content, final boolean hasChildren,
    655            final boolean trimFlag)
    656    {
    657        final boolean shouldTrim =
    658                trimFlag || (StringUtils.isBlank(content) && hasChildren);
    659        return shouldTrim ? content.trim() : content;
    660    }
    661
    662    /**
    663     * Helper method for initializing the attributes of a configuration node
    664     * from the given XML element.
    665     *
    666     * @param element the current XML element
    667     * @return a map with all attribute values extracted for the current node
    668     */
    669    private static Map<String, String> processAttributes(final Element element)
    670    {
    671        final NamedNodeMap attributes = element.getAttributes();
    672        final Map<String, String> attrmap = new HashMap<>();
    673
    674        for (int i = 0; i < attributes.getLength(); ++i)
    675        {
    676            final org.w3c.dom.Node w3cNode = attributes.item(i);
    677            if (w3cNode instanceof Attr)
    678            {
    679                final Attr attr = (Attr) w3cNode;
    680                attrmap.put(attr.getName(), attr.getValue());
    681            }
    682        }
    683
    684        return attrmap;
    685    }
    686
    687    /**
    688     * Creates a new child node, assigns its value, and adds it to its parent.
    689     * This method also deals with elements whose value is a list. In this case
    690     * multiple child elements must be added. The return value is the first
    691     * child node which was added.
    692     *
    693     * @param parent the builder for the parent element
    694     * @param child the builder for the child element
    695     * @param elem the associated XML element
    696     * @param value the value of the child element
    697     * @param trim flag whether texts of elements should be trimmed
    698     * @param attrmap a map with the attributes of the current node
    699     * @param elemRefs a map for assigning references objects to nodes; can be
    700     *        <b>null</b>, then reference objects are irrelevant
    701     * @return the first child node added to the parent
    702     */
    703    private ImmutableNode createChildNodeWithValue(final ImmutableNode.Builder parent,
    704            final ImmutableNode.Builder child, final Element elem, final String value,
    705            final boolean trim, final Map<String, String> attrmap,
    706            final Map<ImmutableNode, Object> elemRefs)
    707    {
    708        ImmutableNode addedChildNode;
    709        Collection<String> values;
    710
    711        if (value != null)
    712        {
    713            values = getListDelimiterHandler().split(value, trim);
    714        }
    715        else
    716        {
    717            values = Collections.emptyList();
    718        }
    719
    720        if (values.size() > 1)
    721        {
    722            final Map<ImmutableNode, Object> refs = isSingleElementList(elem) ? elemRefs : null;
    723            final Iterator<String> it = values.iterator();
    724            // Create new node for the original child's first value
    725            child.value(it.next());
    726            addedChildNode = child.create();
    727            parent.addChild(addedChildNode);
    728            XMLListReference.assignListReference(refs, addedChildNode, elem);
    729
    730            // add multiple new children
    731            while (it.hasNext())
    732            {
    733                final ImmutableNode.Builder c = new ImmutableNode.Builder();
    734                c.name(addedChildNode.getNodeName());
    735                c.value(it.next());
    736                c.addAttributes(attrmap);
    737                final ImmutableNode newChild = c.create();
    738                parent.addChild(newChild);
    739                XMLListReference.assignListReference(refs, newChild, null);
    740            }
    741        }
    742        else if (values.size() == 1)
    743        {
    744            // we will have to replace the value because it might
    745            // contain escaped delimiters
    746            child.value(values.iterator().next());
    747            addedChildNode = child.create();
    748            parent.addChild(addedChildNode);
    749        }
    750        else
    751        {
    752            addedChildNode = child.create();
    753            parent.addChild(addedChildNode);
    754        }
    755
    756        return addedChildNode;
    757    }
    758
    759    /**
    760     * Checks whether an element defines a complete list. If this is the case,
    761     * extended list handling can be applied.
    762     *
    763     * @param element the element to be checked
    764     * @return a flag whether this is the only element defining the list
    765     */
    766    private static boolean isSingleElementList(final Element element)
    767    {
    768        final Node parentNode = element.getParentNode();
    769        return countChildElements(parentNode, element.getTagName()) == 1;
    770    }
    771
    772    /**
    773     * Determines the number of child elements of this given node with the
    774     * specified node name.
    775     *
    776     * @param parent the parent node
    777     * @param name the name in question
    778     * @return the number of child elements with this name
    779     */
    780    private static int countChildElements(final Node parent, final String name)
    781    {
    782        final NodeList childNodes = parent.getChildNodes();
    783        int count = 0;
    784        for (int i = 0; i < childNodes.getLength(); i++)
    785        {
    786            final Node item = childNodes.item(i);
    787            if (item instanceof Element)
    788            {
    789                if (name.equals(((Element) item).getTagName()))
    790                {
    791                    count++;
    792                }
    793            }
    794        }
    795        return count;
    796    }
    797
    798    /**
    799     * Checks whether the content of the current XML element should be trimmed.
    800     * This method checks whether a {@code xml:space} attribute is
    801     * present and evaluates its value. See <a
    802     * href="http://www.w3.org/TR/REC-xml/#sec-white-space">
    803     * http://www.w3.org/TR/REC-xml/#sec-white-space</a> for more details.
    804     *
    805     * @param element the current XML element
    806     * @param currentTrim the current trim flag
    807     * @return a flag whether the content of this element should be trimmed
    808     */
    809    private static boolean shouldTrim(final Element element, final boolean currentTrim)
    810    {
    811        final Attr attr = element.getAttributeNode(ATTR_SPACE);
    812
    813        if (attr == null)
    814        {
    815            return currentTrim;
    816        }
    817        return !VALUE_PRESERVE.equals(attr.getValue());
    818    }
    819
    820    /**
    821     * Creates the {@code DocumentBuilder} to be used for loading files.
    822     * This implementation checks whether a specific
    823     * {@code DocumentBuilder} has been set. If this is the case, this
    824     * one is used. Otherwise a default builder is created. Depending on the
    825     * value of the validating flag this builder will be a validating or a non
    826     * validating {@code DocumentBuilder}.
    827     *
    828     * @return the {@code DocumentBuilder} for loading configuration
    829     * files
    830     * @throws ParserConfigurationException if an error occurs
    831     * @since 1.2
    832     */
    833    protected DocumentBuilder createDocumentBuilder()
    834            throws ParserConfigurationException
    835    {
    836        if (getDocumentBuilder() != null)
    837        {
    838            return getDocumentBuilder();
    839        }
    840        final DocumentBuilderFactory factory = DocumentBuilderFactory
    841                .newInstance();
    842        if (isValidating())
    843        {
    844            factory.setValidating(true);
    845            if (isSchemaValidation())
    846            {
    847                factory.setNamespaceAware(true);
    848                factory.setAttribute(JAXP_SCHEMA_LANGUAGE, W3C_XML_SCHEMA);
    849            }
    850        }
    851
    852        final DocumentBuilder result = factory.newDocumentBuilder();
    853        result.setEntityResolver(this.entityResolver);
    854
    855        if (isValidating())
    856        {
    857            // register an error handler which detects validation errors
    858            result.setErrorHandler(new DefaultHandler()
    859            {
    860                @Override
    861                public void error(final SAXParseException ex) throws SAXException
    862                {
    863                    throw ex;
    864                }
    865            });
    866        }
    867        return result;
    868    }
    869
    870    /**
    871     * Creates and initializes the transformer used for save operations. This
    872     * base implementation initializes all of the default settings like
    873     * indention mode and the DOCTYPE. Derived classes may overload this method
    874     * if they have specific needs.
    875     *
    876     * @return the transformer to use for a save operation
    877     * @throws ConfigurationException if an error occurs
    878     * @since 1.3
    879     */
    880    protected Transformer createTransformer() throws ConfigurationException
    881    {
    882        final Transformer transformer = XMLDocumentHelper.createTransformer();
    883
    884        transformer.setOutputProperty(OutputKeys.INDENT, "yes");
    885        if (locator.getEncoding() != null)
    886        {
    887            transformer.setOutputProperty(OutputKeys.ENCODING, locator.getEncoding());
    888        }
    889        if (publicID != null)
    890        {
    891            transformer.setOutputProperty(OutputKeys.DOCTYPE_PUBLIC,
    892                    publicID);
    893        }
    894        if (systemID != null)
    895        {
    896            transformer.setOutputProperty(OutputKeys.DOCTYPE_SYSTEM,
    897                    systemID);
    898        }
    899
    900        return transformer;
    901    }
    902
    903    /**
    904     * Creates a DOM document from the internal tree of configuration nodes.
    905     *
    906     * @return the new document
    907     * @throws ConfigurationException if an error occurs
    908     */
    909    private Document createDocument() throws ConfigurationException
    910    {
    911        final ReferenceNodeHandler handler = getReferenceHandler();
    912        final XMLDocumentHelper docHelper =
    913                (XMLDocumentHelper) handler.getReference(handler.getRootNode());
    914        final XMLDocumentHelper newHelper =
    915                (docHelper == null) ? XMLDocumentHelper
    916                        .forNewDocument(getRootElementName()) : docHelper
    917                        .createCopy();
    918
    919        final XMLBuilderVisitor builder =
    920                new XMLBuilderVisitor(newHelper, getListDelimiterHandler());
    921        builder.handleRemovedNodes(handler);
    922        builder.processDocument(handler);
    923        initRootElementText(newHelper.getDocument(), getModel()
    924                .getNodeHandler().getRootNode().getValue());
    925        return newHelper.getDocument();
    926    }
    927
    928    /**
    929     * Sets the text of the root element of a newly created XML Document.
    930     *
    931     * @param doc the document
    932     * @param value the new text to be set
    933     */
    934    private void initRootElementText(final Document doc, final Object value)
    935    {
    936        final Element elem = doc.getDocumentElement();
    937        final NodeList children = elem.getChildNodes();
    938
    939        // Remove all existing text nodes
    940        for (int i = 0; i < children.getLength(); i++)
    941        {
    942            final org.w3c.dom.Node nd = children.item(i);
    943            if (nd.getNodeType() == org.w3c.dom.Node.TEXT_NODE)
    944            {
    945                elem.removeChild(nd);
    946            }
    947        }
    948
    949        if (value != null)
    950        {
    951            // Add a new text node
    952            elem.appendChild(doc.createTextNode(String.valueOf(value)));
    953        }
    954    }
    955
    956    /**
    957     * {@inheritDoc} Stores the passed in locator for the upcoming IO operation.
    958     */
    959    @Override
    960    public void initFileLocator(final FileLocator loc)
    961    {
    962        locator = loc;
    963    }
    964
    965    /**
    966     * Loads the configuration from the given reader.
    967     * Note that the {@code clear()} method is not called, so
    968     * the properties contained in the loaded file will be added to the
    969     * current set of properties.
    970     *
    971     * @param in the reader
    972     * @throws ConfigurationException if an error occurs
    973     * @throws IOException if an IO error occurs
    974     */
    975    @Override
    976    public void read(final Reader in) throws ConfigurationException, IOException
    977    {
    978        load(new InputSource(in));
    979    }
    980
    981    /**
    982     * Loads the configuration from the given input stream. This is analogous to
    983     * {@link #read(Reader)}, but data is read from a stream. Note that this
    984     * method will be called most time when reading an XML configuration source.
    985     * By reading XML documents directly from an input stream, the file's
    986     * encoding can be correctly dealt with.
    987     *
    988     * @param in the input stream
    989     * @throws ConfigurationException if an error occurs
    990     * @throws IOException if an IO error occurs
    991     */
    992    @Override
    993    public void read(final InputStream in) throws ConfigurationException, IOException
    994    {
    995        load(new InputSource(in));
    996    }
    997
    998    /**
    999     * Loads a configuration file from the specified input source.
    1000     *
    1001     * @param source the input source
    1002     * @throws ConfigurationException if an error occurs
    1003     */
    1004    private void load(final InputSource source) throws ConfigurationException
    1005    {
    1006        if (locator == null)
    1007        {
    1008            throw new ConfigurationException("Load operation not properly "
    1009                    + "initialized! Do not call read(InputStream) directly,"
    1010                    + " but use a FileHandler to load a configuration.");
    1011        }
    1012
    1013        try
    1014        {
    1015            final URL sourceURL = locator.getSourceURL();
    1016            if (sourceURL != null)
    1017            {
    1018                source.setSystemId(sourceURL.toString());
    1019            }
    1020
    1021            final DocumentBuilder builder = createDocumentBuilder();
    1022            final Document newDocument = builder.parse(source);
    1023            final Document oldDocument = getDocument();
    1024            initProperties(XMLDocumentHelper.forSourceDocument(newDocument),
    1025                    oldDocument == null);
    1026        }
    1027        catch (final SAXParseException spe)
    1028        {
    1029            throw new ConfigurationException("Error parsing " + source.getSystemId(), spe);
    1030        }
    1031        catch (final Exception e)
    1032        {
    1033            this.getLogger().debug("Unable to load the configuration: " + e);
    1034            throw new ConfigurationException("Unable to load the configuration", e);
    1035        }
    1036    }
    1037
    1038    /**
    1039     * Saves the configuration to the specified writer.
    1040     *
    1041     * @param writer the writer used to save the configuration
    1042     * @throws ConfigurationException if an error occurs
    1043     * @throws IOException if an IO error occurs
    1044     */
    1045    @Override
    1046    public void write(final Writer writer) throws ConfigurationException, IOException
    1047    {
    1048        final Transformer transformer = createTransformer();
    1049        final Source source = new DOMSource(createDocument());
    1050        final Result result = new StreamResult(writer);
    1051        XMLDocumentHelper.transform(transformer, source, result);
    1052    }
    1053
    1054    /**
    1055     * Validate the document against the Schema.
    1056     * @throws ConfigurationException if the validation fails.
    1057     */
    1058    public void validate() throws ConfigurationException
    1059    {
    1060        beginWrite(false);
    1061        try
    1062        {
    1063            final Transformer transformer = createTransformer();
    1064            final Source source = new DOMSource(createDocument());
    1065            final StringWriter writer = new StringWriter();
    1066            final Result result = new StreamResult(writer);
    1067            XMLDocumentHelper.transform(transformer, source, result);
    1068            final Reader reader = new StringReader(writer.getBuffer().toString());
    1069            final DocumentBuilder builder = createDocumentBuilder();
    1070            builder.parse(new InputSource(reader));
    1071        }
    1072        catch (final SAXException e)
    1073        {
    1074            throw new ConfigurationException("Validation failed", e);
    1075        }
    1076        catch (final IOException e)
    1077        {
    1078            throw new ConfigurationException("Validation failed", e);
    1079        }
    1080        catch (final ParserConfigurationException pce)
    1081        {
    1082            throw new ConfigurationException("Validation failed", pce);
    1083        }
    1084        finally
    1085        {
    1086            endWrite();
    1087        }
    1088    }
    1089
    1090    /**
    1091     * A concrete {@code BuilderVisitor} that can construct XML
    1092     * documents.
    1093     */
    1094    static class XMLBuilderVisitor extends BuilderVisitor
    1095    {
    1096        /** Stores the document to be constructed. */
    1097        private final Document document;
    1098
    1099        /** The element mapping. */
    1100        private final Map<Node, Node> elementMapping;
    1101
    1102        /** A mapping for the references for new nodes. */
    1103        private final Map<ImmutableNode, Element> newElements;
    1104
    1105        /** Stores the list delimiter handler .*/
    1106        private final ListDelimiterHandler listDelimiterHandler;
    1107
    1108        /**
    1109         * Creates a new instance of {@code XMLBuilderVisitor}.
    1110         *
    1111         * @param docHelper the document helper
    1112         * @param handler the delimiter handler for properties with multiple
    1113         *        values
    1114         */
    1115        public XMLBuilderVisitor(final XMLDocumentHelper docHelper,
    1116                final ListDelimiterHandler handler)
    1117        {
    1118            document = docHelper.getDocument();
    1119            elementMapping = docHelper.getElementMapping();
    1120            listDelimiterHandler = handler;
    1121            newElements = new HashMap<>();
    1122        }
    1123
    1124        /**
    1125         * Processes the specified document, updates element values, and adds
    1126         * new nodes to the hierarchy.
    1127         *
    1128         * @param refHandler the {@code ReferenceNodeHandler}
    1129         */
    1130        public void processDocument(final ReferenceNodeHandler refHandler)
    1131        {
    1132            updateAttributes(refHandler.getRootNode(), document.getDocumentElement());
    1133            NodeTreeWalker.INSTANCE.walkDFS(refHandler.getRootNode(), this,
    1134                    refHandler);
    1135        }
    1136
    1137        /**
    1138         * Updates the current XML document regarding removed nodes. The
    1139         * elements associated with removed nodes are removed from the document.
    1140         *
    1141         * @param refHandler the {@code ReferenceNodeHandler}
    1142         */
    1143        public void handleRemovedNodes(final ReferenceNodeHandler refHandler)
    1144        {
    1145            for (final Object ref : refHandler.removedReferences())
    1146            {
    1147                if (ref instanceof Node)
    1148                {
    1149                    final Node removedElem = (Node) ref;
    1150                    removeReference((Element) elementMapping.get(removedElem));
    1151                }
    1152            }
    1153        }
    1154
    1155        /**
    1156         * {@inheritDoc} This implementation ensures that the correct XML
    1157         * element is created and inserted between the given siblings.
    1158         */
    1159        @Override
    1160        protected void insert(final ImmutableNode newNode, final ImmutableNode parent,
    1161                final ImmutableNode sibling1, final ImmutableNode sibling2,
    1162                final ReferenceNodeHandler refHandler)
    1163        {
    1164            if (XMLListReference.isListNode(newNode, refHandler))
    1165            {
    1166                return;
    1167            }
    1168
    1169            final Element elem = document.createElement(newNode.getNodeName());
    1170            newElements.put(newNode, elem);
    1171            updateAttributes(newNode, elem);
    1172            if (newNode.getValue() != null)
    1173            {
    1174                final String txt =
    1175                        String.valueOf(listDelimiterHandler.escape(
    1176                                newNode.getValue(),
    1177                                ListDelimiterHandler.NOOP_TRANSFORMER));
    1178                elem.appendChild(document.createTextNode(txt));
    1179            }
    1180            if (sibling2 == null)
    1181            {
    1182                getElement(parent, refHandler).appendChild(elem);
    1183            }
    1184            else if (sibling1 != null)
    1185            {
    1186                getElement(parent, refHandler).insertBefore(elem,
    1187                        getElement(sibling1, refHandler).getNextSibling());
    1188            }
    1189            else
    1190            {
    1191                getElement(parent, refHandler).insertBefore(elem,
    1192                        getElement(parent, refHandler).getFirstChild());
    1193            }
    1194        }
    1195
    1196        /**
    1197         * {@inheritDoc} This implementation determines the XML element
    1198         * associated with the given node. Then this element's value and
    1199         * attributes are set accordingly.
    1200         */
    1201        @Override
    1202        protected void update(final ImmutableNode node, final Object reference,
    1203                final ReferenceNodeHandler refHandler)
    1204        {
    1205            if (XMLListReference.isListNode(node, refHandler))
    1206            {
    1207                if (XMLListReference.isFirstListItem(node, refHandler))
    1208                {
    1209                    final String value = XMLListReference.listValue(node, refHandler, listDelimiterHandler);
    1210                    updateElement(node, refHandler, value);
    1211                }
    1212            }
    1213            else
    1214            {
    1215                final Object value = listDelimiterHandler.escape(refHandler.getValue(node),
    1216                        ListDelimiterHandler.NOOP_TRANSFORMER);
    1217                updateElement(node, refHandler, value);
    1218            }
    1219        }
    1220
    1221        private void updateElement(final ImmutableNode node, final ReferenceNodeHandler refHandler,
    1222                                   final Object value)
    1223        {
    1224            final Element element = getElement(node, refHandler);
    1225            updateElement(element, value);
    1226            updateAttributes(node, element);
    1227        }
    1228
    1229        /**
    1230         * Updates the node's value if it represents an element node.
    1231         *
    1232         * @param element the element
    1233         * @param value the new value
    1234         */
    1235        private void updateElement(final Element element, final Object value)
    1236        {
    1237            Text txtNode = findTextNodeForUpdate(element);
    1238            if (value == null)
    1239            {
    1240                // remove text
    1241                if (txtNode != null)
    1242                {
    1243                    element.removeChild(txtNode);
    1244                }
    1245            }
    1246            else
    1247            {
    1248                final String newValue = String.valueOf(value);
    1249                if (txtNode == null)
    1250                {
    1251                    txtNode = document.createTextNode(newValue);
    1252                    if (element.getFirstChild() != null)
    1253                    {
    1254                        element.insertBefore(txtNode, element.getFirstChild());
    1255                    }
    1256                    else
    1257                    {
    1258                        element.appendChild(txtNode);
    1259                    }
    1260                }
    1261                else
    1262                {
    1263                    txtNode.setNodeValue(newValue);
    1264                }
    1265            }
    1266        }
    1267
    1268        /**
    1269         * Updates the associated XML elements when a node is removed.
    1270         * @param element the element to be removed
    1271         */
    1272        private void removeReference(final Element element)
    1273        {
    1274            final org.w3c.dom.Node parentElem = element.getParentNode();
    1275            if (parentElem != null)
    1276            {
    1277                parentElem.removeChild(element);
    1278            }
    1279        }
    1280
    1281        /**
    1282         * Helper method for accessing the element of the specified node.
    1283         *
    1284         * @param node the node
    1285         * @param refHandler the {@code ReferenceNodeHandler}
    1286         * @return the element of this node
    1287         */
    1288        private Element getElement(final ImmutableNode node,
    1289                final ReferenceNodeHandler refHandler)
    1290        {
    1291            final Element elementNew = newElements.get(node);
    1292            if (elementNew != null)
    1293            {
    1294                return elementNew;
    1295            }
    1296
    1297            // special treatment for root node of the hierarchy
    1298            final Object reference = refHandler.getReference(node);
    1299            Node element;
    1300            if (reference instanceof XMLDocumentHelper)
    1301            {
    1302                element =
    1303                        ((XMLDocumentHelper) reference).getDocument()
    1304                                .getDocumentElement();
    1305            }
    1306            else if (reference instanceof XMLListReference)
    1307            {
    1308                element = ((XMLListReference) reference).getElement();
    1309            }
    1310            else
    1311            {
    1312                element = (Node) reference;
    1313            }
    1314            return (element != null) ? (Element) elementMapping.get(element)
    1315                    : document.getDocumentElement();
    1316        }
    1317
    1318        /**
    1319         * Helper method for updating the values of all attributes of the
    1320         * specified node.
    1321         *
    1322         * @param node the affected node
    1323         * @param elem the element that is associated with this node
    1324         */
    1325        private static void updateAttributes(final ImmutableNode node, final Element elem)
    1326        {
    1327            if (node != null && elem != null)
    1328            {
    1329                clearAttributes(elem);
    1330                for (final Map.Entry<String, Object> e : node.getAttributes()
    1331                        .entrySet())
    1332                {
    1333                    if (e.getValue() != null)
    1334                    {
    1335                        elem.setAttribute(e.getKey(), e.getValue().toString());
    1336                    }
    1337                }
    1338            }
    1339        }
    1340
    1341        /**
    1342         * Removes all attributes of the given element.
    1343         *
    1344         * @param elem the element
    1345         */
    1346        private static void clearAttributes(final Element elem)
    1347        {
    1348            final NamedNodeMap attributes = elem.getAttributes();
    1349            for (int i = 0; i < attributes.getLength(); i++)
    1350            {
    1351                elem.removeAttribute(attributes.item(i).getNodeName());
    1352            }
    1353        }
    1354
    1355        /**
    1356         * Returns the only text node of an element for update. This method is
    1357         * called when the element's text changes. Then all text nodes except
    1358         * for the first are removed. A reference to the first is returned or
    1359         * <b>null</b> if there is no text node at all.
    1360         *
    1361         * @param elem the element
    1362         * @return the first and only text node
    1363         */
    1364        private static Text findTextNodeForUpdate(final Element elem)
    1365        {
    1366            Text result = null;
    1367            // Find all Text nodes
    1368            final NodeList children = elem.getChildNodes();
    1369            final Collection<org.w3c.dom.Node> textNodes =
    1370                    new ArrayList<>();
    1371            for (int i = 0; i < children.getLength(); i++)
    1372            {
    1373                final org.w3c.dom.Node nd = children.item(i);
    1374                if (nd instanceof Text)
    1375                {
    1376                    if (result == null)
    1377                    {
    1378                        result = (Text) nd;
    1379                    }
    1380                    else
    1381                    {
    1382                        textNodes.add(nd);
    1383                    }
    1384                }
    1385            }
    1386
    1387            // We don't want CDATAs
    1388            if (result instanceof CDATASection)
    1389            {
    1390                textNodes.add(result);
    1391                result = null;
    1392            }
    1393
    1394            // Remove all but the first Text node
    1395            for (final org.w3c.dom.Node tn : textNodes)
    1396            {
    1397                elem.removeChild(tn);
    1398            }
    1399            return result;
    1400        }
    1401    }
    1402}