    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.io;
    018
    019import java.io.Closeable;
    020import java.io.File;
    021import java.io.IOException;
    022import java.io.InputStream;
    023import java.io.InputStreamReader;
    024import java.io.OutputStream;
    025import java.io.OutputStreamWriter;
    026import java.io.Reader;
    027import java.io.UnsupportedEncodingException;
    028import java.io.Writer;
    029import java.net.MalformedURLException;
    030import java.net.URL;
    031import java.util.List;
    032import java.util.Map;
    033import java.util.concurrent.CopyOnWriteArrayList;
    034import java.util.concurrent.atomic.AtomicReference;
    035
    036import org.apache.commons.configuration2.ex.ConfigurationException;
    037import org.apache.commons.configuration2.io.FileLocator.FileLocatorBuilder;
    038import org.apache.commons.configuration2.sync.LockMode;
    039import org.apache.commons.configuration2.sync.NoOpSynchronizer;
    040import org.apache.commons.configuration2.sync.Synchronizer;
    041import org.apache.commons.configuration2.sync.SynchronizerSupport;
    042import org.apache.commons.logging.LogFactory;
    043
    044/**
    045 * <p>
    046 * A class that manages persistence of an associated {@link FileBased} object.
    047 * </p>
    048 * <p>
    049 * Instances of this class can be used to load and save arbitrary objects implementing the {@code FileBased} interface
    050 * in a convenient way from and to various locations. At construction time the {@code FileBased} object to manage is
    051 * passed in. Basically, this object is assigned a location from which it is loaded and to which it can be saved. The
    052 * following possibilities exist to specify such a location:
    053 * </p>
    054 * <ul>
    055 * <li>URLs: With the method {@code setURL()} a full URL to the configuration source can be specified. This is the most
    056 * flexible way. Note that the {@code save()} methods support only <em>file:</em> URLs.</li>
    057 * <li>Files: The {@code setFile()} method allows to specify the configuration source as a file. This can be either a
    058 * relative or an absolute file. In the former case the file is resolved based on the current directory.</li>
    059 * <li>As file paths in string form: With the {@code setPath()} method a full path to a configuration file can be
    060 * provided as a string.</li>
    061 * <li>Separated as base path and file name: The base path is a string defining either a local directory or a URL. It
    062 * can be set using the {@code setBasePath()} method. The file name, non surprisingly, defines the name of the
    063 * configuration file.</li>
    064 * </ul>
    065 * <p>
    066 * An instance stores a location. The {@code load()} and {@code save()} methods that do not take an argument make use of
    067 * this internal location. Alternatively, it is also possible to use overloaded variants of {@code load()} and
    068 * {@code save()} which expect a location. In these cases the location specified takes precedence over the internal one;
    069 * the internal location is not changed.
    070 * </p>
    071 * <p>
    072 * The actual position of the file to be loaded is determined by a {@link FileLocationStrategy} based on the location
    073 * information that has been provided. By providing a custom location strategy the algorithm for searching files can be
    074 * adapted. Save operations require more explicit information. They cannot rely on a location strategy because the file
    075 * to be written may not yet exist. So there may be some differences in the way location information is interpreted by
    076 * load and save operations. In order to avoid this, the following approach is recommended:
    077 * </p>
    078 * <ul>
    079 * <li>Use the desired {@code setXXX()} methods to define the location of the file to be loaded.</li>
    080 * <li>Call the {@code locate()} method. This method resolves the referenced file (if possible) and fills out all
    081 * supported location information.</li>
    082 * <li>Later on, {@code save()} can be called. This method now has sufficient information to store the file at the
    083 * correct location.</li>
    084 * </ul>
    085 * <p>
    086 * When loading or saving a {@code FileBased} object some additional functionality is performed if the object implements
    087 * one of the following interfaces:
    088 * </p>
    089 * <ul>
    090 * <li>{@code FileLocatorAware}: In this case an object with the current file location is injected before the load or
    091 * save operation is executed. This is useful for {@code FileBased} objects that depend on their current location, e.g.
    092 * to resolve relative path names.</li>
    093 * <li>{@code SynchronizerSupport}: If this interface is implemented, load and save operations obtain a write lock on
    094 * the {@code FileBased} object before they access it. (In case of a save operation, a read lock would probably be
    095 * sufficient, but because of the possible injection of a {@link FileLocator} object it is not allowed to perform
    096 * multiple save operations in parallel; therefore, by obtaining a write lock, we are on the safe side.)</li>
    097 * </ul>
    098 * <p>
    099 * This class is thread-safe.
    100 * </p>
    101 *
    102 * @since 2.0
    103 */
    104public class FileHandler {
    105    /**
    106     * An internal class that performs all update operations of the handler's {@code FileLocator} in a safe way even if
    107     * there is concurrent access. This class implements anon-blocking algorithm for replacing the immutable
    108     * {@code FileLocator} instance stored in an atomic reference by a manipulated instance. (If we already had lambdas,
    109     * this could be done without a class in a more elegant way.)
    110     */
    111    private abstract class AbstractUpdater {
    112        /**
    113         * Performs an update of the enclosing file handler's {@code FileLocator} object.
    114         */
    115        public void update() {
    116            boolean done;
    117            do {
    118                final FileLocator oldLocator = fileLocator.get();
    119                final FileLocatorBuilder builder = FileLocatorUtils.fileLocator(oldLocator);
    120                updateBuilder(builder);
    121                done = fileLocator.compareAndSet(oldLocator, builder.create());
    122            } while (!done);
    123            fireLocationChangedEvent();
    124        }
    125
    126        /**
    127         * Updates the passed in builder object to apply the manipulation to be performed by this {@code Updater}. The builder
    128         * has been setup with the former content of the {@code FileLocator} to be manipulated.
    129         *
    130         * @param builder the builder for creating an updated {@code FileLocator}
    131         */
    132        protected abstract void updateBuilder(FileLocatorBuilder builder);
    133    }
    134
    135    /** Constant for the URI scheme for files. */
    136    private static final String FILE_SCHEME = "file:";
    137
    138    /** Constant for the URI scheme for files with slashes. */
    139    private static final String FILE_SCHEME_SLASH = FILE_SCHEME + "//";
    140
    141    /**
    142     * A dummy implementation of {@code SynchronizerSupport}. This object is used when the file handler's content does not
    143     * implement the {@code SynchronizerSupport} interface. All methods are just empty dummy implementations.
    144     */
    145    private static final SynchronizerSupport DUMMY_SYNC_SUPPORT = new SynchronizerSupport() {
    146        @Override
    147        public Synchronizer getSynchronizer() {
    148            return NoOpSynchronizer.INSTANCE;
    149        }
    150
    151        @Override
    152        public void lock(final LockMode mode) {
    153        }
    154
    155        @Override
    156        public void setSynchronizer(final Synchronizer sync) {
    157        }
    158
    159        @Override
    160        public void unlock(final LockMode mode) {
    161        }
    162    };
    163
    164    /** The file-based object managed by this handler. */
    165    private final FileBased content;
    166
    167    /** A reference to the current {@code FileLocator} object. */
    168    private final AtomicReference<FileLocator> fileLocator;
    169
    170    /** A collection with the registered listeners. */
    171    private final List<FileHandlerListener> listeners = new CopyOnWriteArrayList<>();
    172
    173    /**
    174     * Creates a new instance of {@code FileHandler} which is not associated with a {@code FileBased} object and thus does
    175     * not have a content. Objects of this kind can be used to define a file location, but it is not possible to actually
    176     * load or save data.
    177     */
    178    public FileHandler() {
    179        this(null);
    180    }
    181
    182    /**
    183     * Creates a new instance of {@code FileHandler} and sets the managed {@code FileBased} object.
    184     *
    185     * @param obj the file-based object to manage
    186     */
    187    public FileHandler(final FileBased obj) {
    188        this(obj, emptyFileLocator());
    189    }
    190
    191    /**
    192     * Creates a new instance of {@code FileHandler} which is associated with the given {@code FileBased} object and the
    193     * location defined for the given {@code FileHandler} object. A copy of the location of the given {@code FileHandler} is
    194     * created. This constructor is a possibility to associate a file location with a {@code FileBased} object.
    195     *
    196     * @param obj the {@code FileBased} object to manage
    197     * @param c the {@code FileHandler} from which to copy the location (must not be <b>null</b>)
    198     * @throws IllegalArgumentException if the {@code FileHandler} is <b>null</b>
    199     */
    200    public FileHandler(final FileBased obj, final FileHandler c) {
    201        this(obj, checkSourceHandler(c).getFileLocator());
    202    }
    203
    204    /**
    205     * Creates a new instance of {@code FileHandler} based on the given {@code FileBased} and {@code FileLocator} objects.
    206     *
    207     * @param obj the {@code FileBased} object to manage
    208     * @param locator the {@code FileLocator}
    209     */
    210    private FileHandler(final FileBased obj, final FileLocator locator) {
    211        content = obj;
    212        fileLocator = new AtomicReference<>(locator);
    213    }
    214
    215    /**
    216     * Helper method for checking a file handler which is to be copied. Throws an exception if the handler is <b>null</b>.
    217     *
    218     * @param c the {@code FileHandler} from which to copy the location
    219     * @return the same {@code FileHandler}
    220     */
    221    private static FileHandler checkSourceHandler(final FileHandler c) {
    222        if (c == null) {
    223            throw new IllegalArgumentException("FileHandler to assign must not be null!");
    224        }
    225        return c;
    226    }
    227
    228    /**
    229     * A helper method for closing a stream. Occurring exceptions will be ignored.
    230     *
    231     * @param cl the stream to be closed (may be <b>null</b>)
    232     */
    233    private static void closeSilent(final Closeable cl) {
    234        try {
    235            if (cl != null) {
    236                cl.close();
    237            }
    238        } catch (final IOException e) {
    239            LogFactory.getLog(FileHandler.class).warn("Exception when closing " + cl, e);
    240        }
    241    }
    242
    243    /**
    244     * Creates a {@code File} object from the content of the given {@code FileLocator} object. If the locator is not
    245     * defined, result is <b>null</b>.
    246     *
    247     * @param loc the {@code FileLocator}
    248     * @return a {@code File} object pointing to the associated file
    249     */
    250    private static File createFile(final FileLocator loc) {
    251        if (loc.getFileName() == null && loc.getSourceURL() == null) {
    252            return null;
    253        }
    254        if (loc.getSourceURL() != null) {
    255            return FileLocatorUtils.fileFromURL(loc.getSourceURL());
    256        }
    257        return FileLocatorUtils.getFile(loc.getBasePath(), loc.getFileName());
    258    }
    259
    260    /**
    261     * Creates an uninitialized file locator.
    262     *
    263     * @return the locator
    264     */
    265    private static FileLocator emptyFileLocator() {
    266        return FileLocatorUtils.fileLocator().create();
    267    }
    268
    269    /**
    270     * Creates a new {@code FileHandler} instance from properties stored in a map. This method tries to extract a
    271     * {@link FileLocator} from the map. A new {@code FileHandler} is created based on this {@code FileLocator}.
    272     *
    273     * @param map the map (may be <b>null</b>)
    274     * @return the newly created {@code FileHandler}
    275     * @see FileLocatorUtils#fromMap(Map)
    276     */
    277    public static FileHandler fromMap(final Map<String, ?> map) {
    278        return new FileHandler(null, FileLocatorUtils.fromMap(map));
    279    }
    280
    281    /**
    282     * Normalizes URLs to files. Ensures that file URLs start with the correct protocol.
    283     *
    284     * @param fileName the string to be normalized
    285     * @return the normalized file URL
    286     */
    287    private static String normalizeFileURL(String fileName) {
    288        if (fileName != null && fileName.startsWith(FILE_SCHEME) && !fileName.startsWith(FILE_SCHEME_SLASH)) {
    289            fileName = FILE_SCHEME_SLASH + fileName.substring(FILE_SCHEME.length());
    290        }
    291        return fileName;
    292    }
    293
    294    /**
    295     * Adds a listener to this {@code FileHandler}. It is notified about property changes and IO operations.
    296     *
    297     * @param l the listener to be added (must not be <b>null</b>)
    298     * @throws IllegalArgumentException if the listener is <b>null</b>
    299     */
    300    public void addFileHandlerListener(final FileHandlerListener l) {
    301        if (l == null) {
    302            throw new IllegalArgumentException("Listener must not be null!");
    303        }
    304        listeners.add(l);
    305    }
    306
    307    /**
    308     * Checks whether a content object is available. If not, an exception is thrown. This method is called whenever the
    309     * content object is accessed.
    310     *
    311     * @throws ConfigurationException if not content object is defined
    312     */
    313    private void checkContent() throws ConfigurationException {
    314        if (getContent() == null) {
    315            throw new ConfigurationException("No content available!");
    316        }
    317    }
    318
    319    /**
    320     * Checks whether a content object is available and returns the current {@code FileLocator}. If there is no content
    321     * object, an exception is thrown. This is a typical operation to be performed before a load() or save() operation.
    322     *
    323     * @return the current {@code FileLocator} to be used for the calling operation
    324     * @throws ConfigurationException if not content object is defined
    325     */
    326    private FileLocator checkContentAndGetLocator() throws ConfigurationException {
    327        checkContent();
    328        return getFileLocator();
    329    }
    330
    331    /**
    332     * Clears the location of this {@code FileHandler}. Afterwards this handler does not point to any valid file.
    333     */
    334    public void clearLocation() {
    335        new AbstractUpdater() {
    336            @Override
    337            protected void updateBuilder(final FileLocatorBuilder builder) {
    338                builder.basePath(null).fileName(null).sourceURL(null);
    339            }
    340        }.update();
    341    }
    342
    343    /**
    344     * Creates a {@code FileLocator} which is a copy of the passed in one, but has the given file name set to reference the
    345     * target file.
    346     *
    347     * @param fileName the file name
    348     * @param locator the {@code FileLocator} to copy
    349     * @return the manipulated {@code FileLocator} with the file name
    350     */
    351    private FileLocator createLocatorWithFileName(final String fileName, final FileLocator locator) {
    352        return FileLocatorUtils.fileLocator(locator).sourceURL(null).fileName(fileName).create();
    353    }
    354
    355    /**
    356     * Obtains a {@code SynchronizerSupport} for the current content. If the content implements this interface, it is
    357     * returned. Otherwise, result is a dummy object. This method is called before load and save operations. The returned
    358     * object is used for synchronization.
    359     *
    360     * @return the {@code SynchronizerSupport} for synchronization
    361     */
    362    private SynchronizerSupport fetchSynchronizerSupport() {
    363        if (getContent() instanceof SynchronizerSupport) {
    364            return (SynchronizerSupport) getContent();
    365        }
    366        return DUMMY_SYNC_SUPPORT;
    367    }
    368
    369    /**
    370     * Notifies the registered listeners about a completed load operation.
    371     */
    372    private void fireLoadedEvent() {
    373        listeners.forEach(l -> l.loaded(this));
    374    }
    375
    376    /**
    377     * Notifies the registered listeners about the start of a load operation.
    378     */
    379    private void fireLoadingEvent() {
    380        listeners.forEach(l -> l.loading(this));
    381    }
    382
    383    /**
    384     * Notifies the registered listeners about a property update.
    385     */
    386    private void fireLocationChangedEvent() {
    387        listeners.forEach(l -> l.locationChanged(this));
    388    }
    389
    390    /**
    391     * Notifies the registered listeners about a completed save operation.
    392     */
    393    private void fireSavedEvent() {
    394        listeners.forEach(l -> l.saved(this));
    395    }
    396
    397    /**
    398     * Notifies the registered listeners about the start of a save operation.
    399     */
    400    private void fireSavingEvent() {
    401        listeners.forEach(l -> l.saving(this));
    402    }
    403
    404    /**
    405     * Gets the base path. If no base path is defined, but a URL, the base path is derived from there.
    406     *
    407     * @return the base path
    408     */
    409    public String getBasePath() {
    410        final FileLocator locator = getFileLocator();
    411        if (locator.getBasePath() != null) {
    412            return locator.getBasePath();
    413        }
    414
    415        if (locator.getSourceURL() != null) {
    416            return FileLocatorUtils.getBasePath(locator.getSourceURL());
    417        }
    418
    419        return null;
    420    }
    421
    422    /**
    423     * Gets the {@code FileBased} object associated with this {@code FileHandler}.
    424     *
    425     * @return the associated {@code FileBased} object
    426     */
    427    public final FileBased getContent() {
    428        return content;
    429    }
    430
    431    /**
    432     * Gets the encoding of the associated file. Result can be <b>null</b> if no encoding has been set.
    433     *
    434     * @return the encoding of the associated file
    435     */
    436    public String getEncoding() {
    437        return getFileLocator().getEncoding();
    438    }
    439
    440    /**
    441     * Gets the location of the associated file as a {@code File} object. If the base path is a URL with a protocol
    442     * different than &quot;file&quot;, or the file is within a compressed archive, the return value will not point to a
    443     * valid file object.
    444     *
    445     * @return the location as {@code File} object; this can be <b>null</b>
    446     */
    447    public File getFile() {
    448        return createFile(getFileLocator());
    449    }
    450
    451    /**
    452     * Gets a {@code FileLocator} object with the specification of the file stored by this {@code FileHandler}. Note that
    453     * this method returns the internal data managed by this {@code FileHandler} as it was defined. This is not necessarily
    454     * the same as the data returned by the single access methods like {@code getFileName()} or {@code getURL()}: These
    455     * methods try to derive missing data from other values that have been set.
    456     *
    457     * @return a {@code FileLocator} with the referenced file
    458     */
    459    public FileLocator getFileLocator() {
    460        return fileLocator.get();
    461    }
    462
    463    /**
    464     * Gets the name of the file. If only a URL is defined, the file name is derived from there.
    465     *
    466     * @return the file name
    467     */
    468    public String getFileName() {
    469        final FileLocator locator = getFileLocator();
    470        if (locator.getFileName() != null) {
    471            return locator.getFileName();
    472        }
    473
    474        if (locator.getSourceURL() != null) {
    475            return FileLocatorUtils.getFileName(locator.getSourceURL());
    476        }
    477
    478        return null;
    479    }
    480
    481    /**
    482     * Gets the {@code FileSystem} to be used by this object when locating files. Result is never <b>null</b>; if no file
    483     * system has been set, the default file system is returned.
    484     *
    485     * @return the used {@code FileSystem}
    486     */
    487    public FileSystem getFileSystem() {
    488        return FileLocatorUtils.getFileSystem(getFileLocator());
    489    }
    490
    491    /**
    492     * Gets the {@code FileLocationStrategy} to be applied when accessing the associated file. This method never returns
    493     * <b>null</b>. If a {@code FileLocationStrategy} has been set, it is returned. Otherwise, result is the default
    494     * {@code FileLocationStrategy}.
    495     *
    496     * @return the {@code FileLocationStrategy} to be used
    497     */
    498    public FileLocationStrategy getLocationStrategy() {
    499        return FileLocatorUtils.getLocationStrategy(getFileLocator());
    500    }
    501
    502    /**
    503     * Gets the full path to the associated file. The return value is a valid {@code File} path only if this location is
    504     * based on a file on the local disk. If the file was loaded from a packed archive, the returned value is the string
    505     * form of the URL from which the file was loaded.
    506     *
    507     * @return the full path to the associated file
    508     */
    509    public String getPath() {
    510        final FileLocator locator = getFileLocator();
    511        final File file = createFile(locator);
    512        return FileLocatorUtils.getFileSystem(locator).getPath(file, locator.getSourceURL(), locator.getBasePath(), locator.getFileName());
    513    }
    514
    515    /**
    516     * Gets the location of the associated file as a URL. If a URL is set, it is directly returned. Otherwise, an attempt
    517     * to locate the referenced file is made.
    518     *
    519     * @return a URL to the associated file; can be <b>null</b> if the location is unspecified
    520     */
    521    public URL getURL() {
    522        final FileLocator locator = getFileLocator();
    523        return locator.getSourceURL() != null ? locator.getSourceURL() : FileLocatorUtils.locate(locator);
    524    }
    525
    526    /**
    527     * Injects a {@code FileLocator} pointing to the specified URL if the current {@code FileBased} object implements the
    528     * {@code FileLocatorAware} interface.
    529     *
    530     * @param url the URL for the locator
    531     */
    532    private void injectFileLocator(final URL url) {
    533        if (url == null) {
    534            injectNullFileLocator();
    535        } else if (getContent() instanceof FileLocatorAware) {
    536            final FileLocator locator = prepareNullLocatorBuilder().sourceURL(url).create();
    537            ((FileLocatorAware) getContent()).initFileLocator(locator);
    538        }
    539    }
    540
    541    /**
    542     * Checks whether the associated {@code FileBased} object implements the {@code FileLocatorAware} interface. If this is
    543     * the case, a {@code FileLocator} instance is injected which returns only <b>null</b> values. This method is called if
    544     * no file location is available (e.g. if data is to be loaded from a stream). The encoding of the injected locator is
    545     * derived from this object.
    546     */
    547    private void injectNullFileLocator() {
    548        if (getContent() instanceof FileLocatorAware) {
    549            final FileLocator locator = prepareNullLocatorBuilder().create();
    550            ((FileLocatorAware) getContent()).initFileLocator(locator);
    551        }
    552    }
    553
    554    /**
    555     * Tests whether a location is defined for this {@code FileHandler}.
    556     *
    557     * @return <b>true</b> if a location is defined, <b>false</b> otherwise
    558     */
    559    public boolean isLocationDefined() {
    560        return FileLocatorUtils.isLocationDefined(getFileLocator());
    561    }
    562
    563    /**
    564     * Loads the associated file from the underlying location. If no location has been set, an exception is thrown.
    565     *
    566     * @throws ConfigurationException if loading of the configuration fails
    567     */
    568    public void load() throws ConfigurationException {
    569        load(checkContentAndGetLocator());
    570    }
    571
    572    /**
    573     * Loads the associated file from the specified {@code File}.
    574     *
    575     * @param file the file to load
    576     * @throws ConfigurationException if an error occurs
    577     */
    578    public void load(final File file) throws ConfigurationException {
    579        final URL url;
    580        try {
    581            url = FileLocatorUtils.toURL(file);
    582        } catch (final MalformedURLException e1) {
    583            throw new ConfigurationException("Cannot create URL from file " + file);
    584        }
    585
    586        load(url);
    587    }
    588
    589    /**
    590     * Internal helper method for loading the associated file from the location specified in the given {@code FileLocator}.
    591     *
    592     * @param locator the current {@code FileLocator}
    593     * @throws ConfigurationException if an error occurs
    594     */
    595    private void load(final FileLocator locator) throws ConfigurationException {
    596        load(FileLocatorUtils.locateOrThrow(locator), locator);
    597    }
    598
    599    /**
    600     * Loads the associated file from the specified stream, using the encoding returned by {@link #getEncoding()}.
    601     *
    602     * @param in the input stream
    603     * @throws ConfigurationException if an error occurs during the load operation
    604     */
    605    public void load(final InputStream in) throws ConfigurationException {
    606        load(in, checkContentAndGetLocator());
    607    }
    608
    609    /**
    610     * Internal helper method for loading a file from the given input stream.
    611     *
    612     * @param in the input stream
    613     * @param locator the current {@code FileLocator}
    614     * @throws ConfigurationException if an error occurs
    615     */
    616    private void load(final InputStream in, final FileLocator locator) throws ConfigurationException {
    617        load(in, locator.getEncoding());
    618    }
    619
    620    /**
    621     * Loads the associated file from the specified stream, using the specified encoding. If the encoding is <b>null</b>,
    622     * the default encoding is used.
    623     *
    624     * @param in the input stream
    625     * @param encoding the encoding used, {@code null} to use the default encoding
    626     * @throws ConfigurationException if an error occurs during the load operation
    627     */
    628    public void load(final InputStream in, final String encoding) throws ConfigurationException {
    629        loadFromStream(in, encoding, null);
    630    }
    631
    632    /**
    633     * Loads the associated file from the specified reader.
    634     *
    635     * @param in the reader
    636     * @throws ConfigurationException if an error occurs during the load operation
    637     */
    638    public void load(final Reader in) throws ConfigurationException {
    639        checkContent();
    640        injectNullFileLocator();
    641        loadFromReader(in);
    642    }
    643
    644    /**
    645     * Loads the associated file from the given file name. The file name is interpreted in the context of the already set
    646     * location (e.g. if it is a relative file name, a base path is applied if available). The underlying location is not
    647     * changed.
    648     *
    649     * @param fileName the name of the file to be loaded
    650     * @throws ConfigurationException if an error occurs
    651     */
    652    public void load(final String fileName) throws ConfigurationException {
    653        load(fileName, checkContentAndGetLocator());
    654    }
    655
    656    /**
    657     * Internal helper method for loading a file from a file name.
    658     *
    659     * @param fileName the file name
    660     * @param locator the current {@code FileLocator}
    661     * @throws ConfigurationException if an error occurs
    662     */
    663    private void load(final String fileName, final FileLocator locator) throws ConfigurationException {
    664        final FileLocator locFileName = createLocatorWithFileName(fileName, locator);
    665        final URL url = FileLocatorUtils.locateOrThrow(locFileName);
    666        load(url, locator);
    667    }
    668
    669    /**
    670     * Loads the associated file from the specified URL. The location stored in this object is not changed.
    671     *
    672     * @param url the URL of the file to be loaded
    673     * @throws ConfigurationException if an error occurs
    674     */
    675    public void load(final URL url) throws ConfigurationException {
    676        load(url, checkContentAndGetLocator());
    677    }
    678
    679    /**
    680     * Internal helper method for loading a file from the given URL.
    681     *
    682     * @param url the URL
    683     * @param locator the current {@code FileLocator}
    684     * @throws ConfigurationException if an error occurs
    685     */
    686    private void load(final URL url, final FileLocator locator) throws ConfigurationException {
    687        InputStream in = null;
    688
    689        try {
    690            final FileSystem fileSystem = FileLocatorUtils.getFileSystem(locator);
    691            final URLConnectionOptions urlConnectionOptions = locator.getURLConnectionOptions();
    692            in = urlConnectionOptions == null ? fileSystem.getInputStream(url) : fileSystem.getInputStream(url, urlConnectionOptions);
    693            loadFromStream(in, locator.getEncoding(), url);
    694        } catch (final ConfigurationException e) {
    695            throw e;
    696        } catch (final Exception e) {
    697            throw new ConfigurationException("Unable to load the configuration from the URL " + url, e);
    698        } finally {
    699            closeSilent(in);
    700        }
    701    }
    702
    703    /**
    704     * Internal helper method for loading a file from the given reader.
    705     *
    706     * @param in the reader
    707     * @throws ConfigurationException if an error occurs
    708     */
    709    private void loadFromReader(final Reader in) throws ConfigurationException {
    710        fireLoadingEvent();
    711        try {
    712            getContent().read(in);
    713        } catch (final IOException ioex) {
    714            throw new ConfigurationException(ioex);
    715        } finally {
    716            fireLoadedEvent();
    717        }
    718    }
    719
    720    /**
    721     * Internal helper method for loading a file from an input stream.
    722     *
    723     * @param in the input stream
    724     * @param encoding the encoding
    725     * @param url the URL of the file to be loaded (if known)
    726     * @throws ConfigurationException if an error occurs
    727     */
    728    private void loadFromStream(final InputStream in, final String encoding, final URL url) throws ConfigurationException {
    729        checkContent();
    730        final SynchronizerSupport syncSupport = fetchSynchronizerSupport();
    731        syncSupport.lock(LockMode.WRITE);
    732        try {
    733            injectFileLocator(url);
    734
    735            if (getContent() instanceof InputStreamSupport) {
    736                loadFromStreamDirectly(in);
    737            } else {
    738                loadFromTransformedStream(in, encoding);
    739            }
    740        } finally {
    741            syncSupport.unlock(LockMode.WRITE);
    742        }
    743    }
    744
    745    /**
    746     * Loads data from an input stream if the associated {@code FileBased} object implements the {@code InputStreamSupport}
    747     * interface.
    748     *
    749     * @param in the input stream
    750     * @throws ConfigurationException if an error occurs
    751     */
    752    private void loadFromStreamDirectly(final InputStream in) throws ConfigurationException {
    753        try {
    754            ((InputStreamSupport) getContent()).read(in);
    755        } catch (final IOException e) {
    756            throw new ConfigurationException(e);
    757        }
    758    }
    759
    760    /**
    761     * Internal helper method for transforming an input stream to a reader and reading its content.
    762     *
    763     * @param in the input stream
    764     * @param encoding the encoding
    765     * @throws ConfigurationException if an error occurs
    766     */
    767    private void loadFromTransformedStream(final InputStream in, final String encoding) throws ConfigurationException {
    768        Reader reader = null;
    769
    770        if (encoding != null) {
    771            try {
    772                reader = new InputStreamReader(in, encoding);
    773            } catch (final UnsupportedEncodingException e) {
    774                throw new ConfigurationException("The requested encoding is not supported, try the default encoding.", e);
    775            }
    776        }
    777
    778        if (reader == null) {
    779            reader = new InputStreamReader(in);
    780        }
    781
    782        loadFromReader(reader);
    783    }
    784
    785    /**
    786     * Locates the referenced file if necessary and ensures that the associated {@link FileLocator} is fully initialized.
    787     * When accessing the referenced file the information stored in the associated {@code FileLocator} is used. If this
    788     * information is incomplete (e.g. only the file name is set), an attempt to locate the file may have to be performed on
    789     * each access. By calling this method such an attempt is performed once, and the results of a successful localization
    790     * are stored. Hence, later access to the referenced file can be more efficient. Also, all properties pointing to the
    791     * referenced file in this object's {@code FileLocator} are set (i.e. the URL, the base path, and the file name). If the
    792     * referenced file cannot be located, result is <b>false</b>. This means that the information in the current
    793     * {@code FileLocator} is insufficient or wrong. If the {@code FileLocator} is already fully defined, it is not changed.
    794     *
    795     * @return a flag whether the referenced file could be located successfully
    796     * @see FileLocatorUtils#fullyInitializedLocator(FileLocator)
    797     */
    798    public boolean locate() {
    799        boolean result;
    800        boolean done;
    801
    802        do {
    803            final FileLocator locator = getFileLocator();
    804            FileLocator fullLocator = FileLocatorUtils.fullyInitializedLocator(locator);
    805            if (fullLocator == null) {
    806                result = false;
    807                fullLocator = locator;
    808            } else {
    809                result = fullLocator != locator || FileLocatorUtils.isFullyInitialized(locator);
    810            }
    811            done = fileLocator.compareAndSet(locator, fullLocator);
    812        } while (!done);
    813
    814        return result;
    815    }
    816
    817    /**
    818     * Prepares a builder for a {@code FileLocator} which does not have a defined file location. Other properties (e.g.
    819     * encoding or file system) are initialized from the {@code FileLocator} associated with this object.
    820     *
    821     * @return the initialized builder for a {@code FileLocator}
    822     */
    823    private FileLocatorBuilder prepareNullLocatorBuilder() {
    824        return FileLocatorUtils.fileLocator(getFileLocator()).sourceURL(null).basePath(null).fileName(null);
    825    }
    826
    827    /**
    828     * Removes the specified listener from this object.
    829     *
    830     * @param l the listener to be removed
    831     */
    832    public void removeFileHandlerListener(final FileHandlerListener l) {
    833        listeners.remove(l);
    834    }
    835
    836    /**
    837     * Resets the {@code FileSystem} used by this object. It is set to the default file system.
    838     */
    839    public void resetFileSystem() {
    840        setFileSystem(null);
    841    }
    842
    843    /**
    844     * Saves the associated file to the current location set for this object. Before this method can be called a valid
    845     * location must have been set.
    846     *
    847     * @throws ConfigurationException if an error occurs or no location has been set yet
    848     */
    849    public void save() throws ConfigurationException {
    850        save(checkContentAndGetLocator());
    851    }
    852
    853    /**
    854     * Saves the associated file to the specified {@code File}. The file is created automatically if it doesn't exist. This
    855     * does not change the location of this object (use {@link #setFile} if you need it).
    856     *
    857     * @param file the target file
    858     * @throws ConfigurationException if an error occurs during the save operation
    859     */
    860    public void save(final File file) throws ConfigurationException {
    861        save(file, checkContentAndGetLocator());
    862    }
    863
    864    /**
    865     * Internal helper method for saving data to the given {@code File}.
    866     *
    867     * @param file the target file
    868     * @param locator the current {@code FileLocator}
    869     * @throws ConfigurationException if an error occurs during the save operation
    870     */
    871    private void save(final File file, final FileLocator locator) throws ConfigurationException {
    872        OutputStream out = null;
    873
    874        try {
    875            out = FileLocatorUtils.getFileSystem(locator).getOutputStream(file);
    876            saveToStream(out, locator.getEncoding(), file.toURI().toURL());
    877        } catch (final MalformedURLException muex) {
    878            throw new ConfigurationException(muex);
    879        } finally {
    880            closeSilent(out);
    881        }
    882    }
    883
    884    /**
    885     * Internal helper method for saving data to the internal location stored for this object.
    886     *
    887     * @param locator the current {@code FileLocator}
    888     * @throws ConfigurationException if an error occurs during the save operation
    889     */
    890    private void save(final FileLocator locator) throws ConfigurationException {
    891        if (!FileLocatorUtils.isLocationDefined(locator)) {
    892            throw new ConfigurationException("No file location has been set!");
    893        }
    894
    895        if (locator.getSourceURL() != null) {
    896            save(locator.getSourceURL(), locator);
    897        } else {
    898            save(locator.getFileName(), locator);
    899        }
    900    }
    901
    902    /**
    903     * Saves the associated file to the specified stream using the encoding returned by {@link #getEncoding()}.
    904     *
    905     * @param out the output stream
    906     * @throws ConfigurationException if an error occurs during the save operation
    907     */
    908    public void save(final OutputStream out) throws ConfigurationException {
    909        save(out, checkContentAndGetLocator());
    910    }
    911
    912    /**
    913     * Internal helper method for saving a file to the given output stream.
    914     *
    915     * @param out the output stream
    916     * @param locator the current {@code FileLocator}
    917     * @throws ConfigurationException if an error occurs during the save operation
    918     */
    919    private void save(final OutputStream out, final FileLocator locator) throws ConfigurationException {
    920        save(out, locator.getEncoding());
    921    }
    922
    923    /**
    924     * Saves the associated file to the specified stream using the specified encoding. If the encoding is <b>null</b>, the
    925     * default encoding is used.
    926     *
    927     * @param out the output stream
    928     * @param encoding the encoding to be used, {@code null} to use the default encoding
    929     * @throws ConfigurationException if an error occurs during the save operation
    930     */
    931    public void save(final OutputStream out, final String encoding) throws ConfigurationException {
    932        saveToStream(out, encoding, null);
    933    }
    934
    935    /**
    936     * Saves the associated file to the specified file name. This does not change the location of this object (use
    937     * {@link #setFileName(String)} if you need it).
    938     *
    939     * @param fileName the file name
    940     * @throws ConfigurationException if an error occurs during the save operation
    941     */
    942    public void save(final String fileName) throws ConfigurationException {
    943        save(fileName, checkContentAndGetLocator());
    944    }
    945
    946    /**
    947     * Internal helper method for saving data to the given file name.
    948     *
    949     * @param fileName the path to the target file
    950     * @param locator the current {@code FileLocator}
    951     * @throws ConfigurationException if an error occurs during the save operation
    952     */
    953    private void save(final String fileName, final FileLocator locator) throws ConfigurationException {
    954        final URL url;
    955        try {
    956            url = FileLocatorUtils.getFileSystem(locator).getURL(locator.getBasePath(), fileName);
    957        } catch (final MalformedURLException e) {
    958            throw new ConfigurationException(e);
    959        }
    960
    961        if (url == null) {
    962            throw new ConfigurationException("Cannot locate configuration source " + fileName);
    963        }
    964        save(url, locator);
    965    }
    966
    967    /**
    968     * Saves the associated file to the specified URL. This does not change the location of this object (use
    969     * {@link #setURL(URL)} if you need it).
    970     *
    971     * @param url the URL
    972     * @throws ConfigurationException if an error occurs during the save operation
    973     */
    974    public void save(final URL url) throws ConfigurationException {
    975        save(url, checkContentAndGetLocator());
    976    }
    977
    978    /**
    979     * Internal helper method for saving data to the given URL.
    980     *
    981     * @param url the target URL
    982     * @param locator the {@code FileLocator}
    983     * @throws ConfigurationException if an error occurs during the save operation
    984     */
    985    private void save(final URL url, final FileLocator locator) throws ConfigurationException {
    986        OutputStream out = null;
    987        try {
    988            out = FileLocatorUtils.getFileSystem(locator).getOutputStream(url);
    989            saveToStream(out, locator.getEncoding(), url);
    990            if (out instanceof VerifiableOutputStream) {
    991                try {
    992                    ((VerifiableOutputStream) out).verify();
    993                } catch (final IOException e) {
    994                    throw new ConfigurationException(e);
    995                }
    996            }
    997        } finally {
    998            closeSilent(out);
    999        }
    1000    }
    1001
    1002    /**
    1003     * Saves the associated file to the given {@code Writer}.
    1004     *
    1005     * @param out the {@code Writer}
    1006     * @throws ConfigurationException if an error occurs during the save operation
    1007     */
    1008    public void save(final Writer out) throws ConfigurationException {
    1009        checkContent();
    1010        injectNullFileLocator();
    1011        saveToWriter(out);
    1012    }
    1013
    1014    /**
    1015     * Internal helper method for saving a file to the given stream.
    1016     *
    1017     * @param out the output stream
    1018     * @param encoding the encoding
    1019     * @param url the URL of the output file if known
    1020     * @throws ConfigurationException if an error occurs
    1021     */
    1022    private void saveToStream(final OutputStream out, final String encoding, final URL url) throws ConfigurationException {
    1023        checkContent();
    1024        final SynchronizerSupport syncSupport = fetchSynchronizerSupport();
    1025        syncSupport.lock(LockMode.WRITE);
    1026        try {
    1027            injectFileLocator(url);
    1028            Writer writer = null;
    1029
    1030            if (encoding != null) {
    1031                try {
    1032                    writer = new OutputStreamWriter(out, encoding);
    1033                } catch (final UnsupportedEncodingException e) {
    1034                    throw new ConfigurationException("The requested encoding is not supported, try the default encoding.", e);
    1035                }
    1036            }
    1037
    1038            if (writer == null) {
    1039                writer = new OutputStreamWriter(out);
    1040            }
    1041
    1042            saveToWriter(writer);
    1043        } finally {
    1044            syncSupport.unlock(LockMode.WRITE);
    1045        }
    1046    }
    1047
    1048    /**
    1049     * Internal helper method for saving a file into the given writer.
    1050     *
    1051     * @param out the writer
    1052     * @throws ConfigurationException if an error occurs
    1053     */
    1054    private void saveToWriter(final Writer out) throws ConfigurationException {
    1055        fireSavingEvent();
    1056        try {
    1057            getContent().write(out);
    1058        } catch (final IOException ioex) {
    1059            throw new ConfigurationException(ioex);
    1060        } finally {
    1061            fireSavedEvent();
    1062        }
    1063    }
    1064
    1065    /**
    1066     * Sets the base path. The base path is typically either a path to a directory or a URL. Together with the value passed
    1067     * to the {@code setFileName()} method it defines the location of the configuration file to be loaded. The strategies
    1068     * for locating the file are quite tolerant. For instance if the file name is already an absolute path or a fully
    1069     * defined URL, the base path will be ignored. The base path can also be a URL, in which case the file name is
    1070     * interpreted in this URL's context. If other methods are used for determining the location of the associated file
    1071     * (e.g. {@code setFile()} or {@code setURL()}), the base path is automatically set. Setting the base path using this
    1072     * method automatically sets the URL to <b>null</b> because it has to be determined anew based on the file name and the
    1073     * base path.
    1074     *
    1075     * @param basePath the base path.
    1076     */
    1077    public void setBasePath(final String basePath) {
    1078        final String path = normalizeFileURL(basePath);
    1079        new AbstractUpdater() {
    1080            @Override
    1081            protected void updateBuilder(final FileLocatorBuilder builder) {
    1082                builder.basePath(path);
    1083                builder.sourceURL(null);
    1084            }
    1085        }.update();
    1086    }
    1087
    1088    /**
    1089     * Sets the encoding of the associated file. The encoding applies if binary files are loaded. Note that in this case
    1090     * setting an encoding is recommended; otherwise the platform's default encoding is used.
    1091     *
    1092     * @param encoding the encoding of the associated file
    1093     */
    1094    public void setEncoding(final String encoding) {
    1095        new AbstractUpdater() {
    1096            @Override
    1097            protected void updateBuilder(final FileLocatorBuilder builder) {
    1098                builder.encoding(encoding);
    1099            }
    1100        }.update();
    1101    }
    1102
    1103    /**
    1104     * Sets the location of the associated file as a {@code File} object. The passed in {@code File} is made absolute if it
    1105     * is not yet. Then the file's path component becomes the base path and its name component becomes the file name.
    1106     *
    1107     * @param file the location of the associated file
    1108     */
    1109    public void setFile(final File file) {
    1110        final String fileName = file.getName();
    1111        final String basePath = file.getParentFile() != null ? file.getParentFile().getAbsolutePath() : null;
    1112        new AbstractUpdater() {
    1113            @Override
    1114            protected void updateBuilder(final FileLocatorBuilder builder) {
    1115                builder.fileName(fileName).basePath(basePath).sourceURL(null);
    1116            }
    1117        }.update();
    1118    }
    1119
    1120    /**
    1121     * Sets the file to be accessed by this {@code FileHandler} as a {@code FileLocator} object.
    1122     *
    1123     * @param locator the {@code FileLocator} with the definition of the file to be accessed (must not be <b>null</b>
    1124     * @throws IllegalArgumentException if the {@code FileLocator} is <b>null</b>
    1125     */
    1126    public void setFileLocator(final FileLocator locator) {
    1127        if (locator == null) {
    1128            throw new IllegalArgumentException("FileLocator must not be null!");
    1129        }
    1130
    1131        fileLocator.set(locator);
    1132        fireLocationChangedEvent();
    1133    }
    1134
    1135    /**
    1136     * Sets the name of the file. The passed in file name can contain a relative path. It must be used when referring files
    1137     * with relative paths from classpath. Use {@code setPath()} to set a full qualified file name. The URL is set to
    1138     * <b>null</b> as it has to be determined anew based on the file name and the base path.
    1139     *
    1140     * @param fileName the name of the file
    1141     */
    1142    public void setFileName(final String fileName) {
    1143        final String name = normalizeFileURL(fileName);
    1144        new AbstractUpdater() {
    1145            @Override
    1146            protected void updateBuilder(final FileLocatorBuilder builder) {
    1147                builder.fileName(name);
    1148                builder.sourceURL(null);
    1149            }
    1150        }.update();
    1151    }
    1152
    1153    /**
    1154     * Sets the {@code FileSystem} to be used by this object when locating files. If a <b>null</b> value is passed in, the
    1155     * file system is reset to the default file system.
    1156     *
    1157     * @param fileSystem the {@code FileSystem}
    1158     */
    1159    public void setFileSystem(final FileSystem fileSystem) {
    1160        new AbstractUpdater() {
    1161            @Override
    1162            protected void updateBuilder(final FileLocatorBuilder builder) {
    1163                builder.fileSystem(fileSystem);
    1164            }
    1165        }.update();
    1166    }
    1167
    1168    /**
    1169     * Sets the {@code FileLocationStrategy} to be applied when accessing the associated file. The strategy is stored in the
    1170     * underlying {@link FileLocator}. The argument can be <b>null</b>; this causes the default {@code FileLocationStrategy}
    1171     * to be used.
    1172     *
    1173     * @param strategy the {@code FileLocationStrategy}
    1174     * @see FileLocatorUtils#DEFAULT_LOCATION_STRATEGY
    1175     */
    1176    public void setLocationStrategy(final FileLocationStrategy strategy) {
    1177        new AbstractUpdater() {
    1178            @Override
    1179            protected void updateBuilder(final FileLocatorBuilder builder) {
    1180                builder.locationStrategy(strategy);
    1181            }
    1182
    1183        }.update();
    1184    }
    1185
    1186    /**
    1187     * Sets the location of the associated file as a full or relative path name. The passed in path should represent a valid
    1188     * file name on the file system. It must not be used to specify relative paths for files that exist in classpath, either
    1189     * plain file system or compressed archive, because this method expands any relative path to an absolute one which may
    1190     * end in an invalid absolute path for classpath references.
    1191     *
    1192     * @param path the full path name of the associated file
    1193     */
    1194    public void setPath(final String path) {
    1195        setFile(new File(path));
    1196    }
    1197
    1198    /**
    1199     * Sets the location of the associated file as a URL. For loading this can be an arbitrary URL with a supported
    1200     * protocol. If the file is to be saved, too, a URL with the &quot;file&quot; protocol should be provided. This method
    1201     * sets the file name and the base path to <b>null</b>. They have to be determined anew based on the new URL.
    1202     *
    1203     * @param url the location of the file as URL
    1204     */
    1205    public void setURL(final URL url) {
    1206        setURL(url, URLConnectionOptions.DEFAULT);
    1207    }
    1208
    1209    /**
    1210     * Sets the location of the associated file as a URL. For loading this can be an arbitrary URL with a supported
    1211     * protocol. If the file is to be saved, too, a URL with the &quot;file&quot; protocol should be provided. This method
    1212     * sets the file name and the base path to <b>null</b>. They have to be determined anew based on the new URL.
    1213     *
    1214     * @param url the location of the file as URL
    1215     * @param urlConnectionOptions URL connection options
    1216     * @since 2.8.0
    1217     */
    1218    public void setURL(final URL url, final URLConnectionOptions urlConnectionOptions) {
    1219        new AbstractUpdater() {
    1220            @Override
    1221            protected void updateBuilder(final FileLocatorBuilder builder) {
    1222                builder.sourceURL(url);
    1223                builder.urlConnectionOptions(urlConnectionOptions);
    1224                builder.basePath(null).fileName(null);
    1225            }
    1226        }.update();
    1227    }
    1228}