FileHandler.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.commons.configuration2.io;
import java.io.Closeable;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;
import java.util.Map;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.atomic.AtomicReference;
import org.apache.commons.configuration2.ex.ConfigurationException;
import org.apache.commons.configuration2.io.FileLocator.FileLocatorBuilder;
import org.apache.commons.configuration2.sync.LockMode;
import org.apache.commons.configuration2.sync.NoOpSynchronizer;
import org.apache.commons.configuration2.sync.Synchronizer;
import org.apache.commons.configuration2.sync.SynchronizerSupport;
import org.apache.commons.logging.LogFactory;
/**
* <p>
* A class that manages persistence of an associated {@link FileBased} object.
* </p>
* <p>
* Instances of this class can be used to load and save arbitrary objects implementing the {@code FileBased} interface
* in a convenient way from and to various locations. At construction time the {@code FileBased} object to manage is
* passed in. Basically, this object is assigned a location from which it is loaded and to which it can be saved. The
* following possibilities exist to specify such a location:
* </p>
* <ul>
* <li>URLs: With the method {@code setURL()} a full URL to the configuration source can be specified. This is the most
* flexible way. Note that the {@code save()} methods support only <em>file:</em> URLs.</li>
* <li>Files: The {@code setFile()} method allows to specify the configuration source as a file. This can be either a
* relative or an absolute file. In the former case the file is resolved based on the current directory.</li>
* <li>As file paths in string form: With the {@code setPath()} method a full path to a configuration file can be
* provided as a string.</li>
* <li>Separated as base path and file name: The base path is a string defining either a local directory or a URL. It
* can be set using the {@code setBasePath()} method. The file name, non surprisingly, defines the name of the
* configuration file.</li>
* </ul>
* <p>
* An instance stores a location. The {@code load()} and {@code save()} methods that do not take an argument make use of
* this internal location. Alternatively, it is also possible to use overloaded variants of {@code load()} and
* {@code save()} which expect a location. In these cases the location specified takes precedence over the internal one;
* the internal location is not changed.
* </p>
* <p>
* The actual position of the file to be loaded is determined by a {@link FileLocationStrategy} based on the location
* information that has been provided. By providing a custom location strategy the algorithm for searching files can be
* adapted. Save operations require more explicit information. They cannot rely on a location strategy because the file
* to be written may not yet exist. So there may be some differences in the way location information is interpreted by
* load and save operations. In order to avoid this, the following approach is recommended:
* </p>
* <ul>
* <li>Use the desired {@code setXXX()} methods to define the location of the file to be loaded.</li>
* <li>Call the {@code locate()} method. This method resolves the referenced file (if possible) and fills out all
* supported location information.</li>
* <li>Later on, {@code save()} can be called. This method now has sufficient information to store the file at the
* correct location.</li>
* </ul>
* <p>
* When loading or saving a {@code FileBased} object some additional functionality is performed if the object implements
* one of the following interfaces:
* </p>
* <ul>
* <li>{@code FileLocatorAware}: In this case an object with the current file location is injected before the load or
* save operation is executed. This is useful for {@code FileBased} objects that depend on their current location, e.g.
* to resolve relative path names.</li>
* <li>{@code SynchronizerSupport}: If this interface is implemented, load and save operations obtain a write lock on
* the {@code FileBased} object before they access it. (In case of a save operation, a read lock would probably be
* sufficient, but because of the possible injection of a {@link FileLocator} object it is not allowed to perform
* multiple save operations in parallel; therefore, by obtaining a write lock, we are on the safe side.)</li>
* </ul>
* <p>
* This class is thread-safe.
* </p>
*
* @since 2.0
*/
public class FileHandler {
/**
* An internal class that performs all update operations of the handler's {@code FileLocator} in a safe way even if
* there is concurrent access. This class implements anon-blocking algorithm for replacing the immutable
* {@code FileLocator} instance stored in an atomic reference by a manipulated instance. (If we already had lambdas,
* this could be done without a class in a more elegant way.)
*/
private abstract class AbstractUpdater {
/**
* Performs an update of the enclosing file handler's {@code FileLocator} object.
*/
public void update() {
boolean done;
do {
final FileLocator oldLocator = fileLocator.get();
final FileLocatorBuilder builder = FileLocatorUtils.fileLocator(oldLocator);
updateBuilder(builder);
done = fileLocator.compareAndSet(oldLocator, builder.create());
} while (!done);
fireLocationChangedEvent();
}
/**
* Updates the passed in builder object to apply the manipulation to be performed by this {@code Updater}. The builder
* has been setup with the former content of the {@code FileLocator} to be manipulated.
*
* @param builder the builder for creating an updated {@code FileLocator}
*/
protected abstract void updateBuilder(FileLocatorBuilder builder);
}
/** Constant for the URI scheme for files. */
private static final String FILE_SCHEME = "file:";
/** Constant for the URI scheme for files with slashes. */
private static final String FILE_SCHEME_SLASH = FILE_SCHEME + "//";
/**
* A dummy implementation of {@code SynchronizerSupport}. This object is used when the file handler's content does not
* implement the {@code SynchronizerSupport} interface. All methods are just empty dummy implementations.
*/
private static final SynchronizerSupport DUMMY_SYNC_SUPPORT = new SynchronizerSupport() {
@Override
public Synchronizer getSynchronizer() {
return NoOpSynchronizer.INSTANCE;
}
@Override
public void lock(final LockMode mode) {
// empty
}
@Override
public void setSynchronizer(final Synchronizer sync) {
// empty
}
@Override
public void unlock(final LockMode mode) {
// empty
}
};
/**
* Helper method for checking a file handler which is to be copied. Throws an exception if the handler is <b>null</b>.
*
* @param c the {@code FileHandler} from which to copy the location
* @return the same {@code FileHandler}
*/
private static FileHandler checkSourceHandler(final FileHandler c) {
if (c == null) {
throw new IllegalArgumentException("FileHandler to assign must not be null!");
}
return c;
}
/**
* A helper method for closing a stream. Occurring exceptions will be ignored.
*
* @param cl the stream to be closed (may be <b>null</b>)
*/
private static void closeSilent(final Closeable cl) {
try {
if (cl != null) {
cl.close();
}
} catch (final IOException e) {
LogFactory.getLog(FileHandler.class).warn("Exception when closing " + cl, e);
}
}
/**
* Creates a {@code File} object from the content of the given {@code FileLocator} object. If the locator is not
* defined, result is <b>null</b>.
*
* @param loc the {@code FileLocator}
* @return a {@code File} object pointing to the associated file
*/
private static File createFile(final FileLocator loc) {
if (loc.getFileName() == null && loc.getSourceURL() == null) {
return null;
}
if (loc.getSourceURL() != null) {
return FileLocatorUtils.fileFromURL(loc.getSourceURL());
}
return FileLocatorUtils.getFile(loc.getBasePath(), loc.getFileName());
}
/**
* Creates an uninitialized file locator.
*
* @return the locator
*/
private static FileLocator emptyFileLocator() {
return FileLocatorUtils.fileLocator().create();
}
/**
* Creates a new {@code FileHandler} instance from properties stored in a map. This method tries to extract a
* {@link FileLocator} from the map. A new {@code FileHandler} is created based on this {@code FileLocator}.
*
* @param map the map (may be <b>null</b>)
* @return the newly created {@code FileHandler}
* @see FileLocatorUtils#fromMap(Map)
*/
public static FileHandler fromMap(final Map<String, ?> map) {
return new FileHandler(null, FileLocatorUtils.fromMap(map));
}
/**
* Normalizes URLs to files. Ensures that file URLs start with the correct protocol.
*
* @param fileName the string to be normalized
* @return the normalized file URL
*/
private static String normalizeFileURL(String fileName) {
if (fileName != null && fileName.startsWith(FILE_SCHEME) && !fileName.startsWith(FILE_SCHEME_SLASH)) {
fileName = FILE_SCHEME_SLASH + fileName.substring(FILE_SCHEME.length());
}
return fileName;
}
/** The file-based object managed by this handler. */
private final FileBased content;
/** A reference to the current {@code FileLocator} object. */
private final AtomicReference<FileLocator> fileLocator;
/** A collection with the registered listeners. */
private final List<FileHandlerListener> listeners = new CopyOnWriteArrayList<>();
/**
* Creates a new instance of {@code FileHandler} which is not associated with a {@code FileBased} object and thus does
* not have a content. Objects of this kind can be used to define a file location, but it is not possible to actually
* load or save data.
*/
public FileHandler() {
this(null);
}
/**
* Creates a new instance of {@code FileHandler} and sets the managed {@code FileBased} object.
*
* @param obj the file-based object to manage
*/
public FileHandler(final FileBased obj) {
this(obj, emptyFileLocator());
}
/**
* Creates a new instance of {@code FileHandler} which is associated with the given {@code FileBased} object and the
* location defined for the given {@code FileHandler} object. A copy of the location of the given {@code FileHandler} is
* created. This constructor is a possibility to associate a file location with a {@code FileBased} object.
*
* @param obj the {@code FileBased} object to manage
* @param c the {@code FileHandler} from which to copy the location (must not be <b>null</b>)
* @throws IllegalArgumentException if the {@code FileHandler} is <b>null</b>
*/
public FileHandler(final FileBased obj, final FileHandler c) {
this(obj, checkSourceHandler(c).getFileLocator());
}
/**
* Creates a new instance of {@code FileHandler} based on the given {@code FileBased} and {@code FileLocator} objects.
*
* @param obj the {@code FileBased} object to manage
* @param locator the {@code FileLocator}
*/
private FileHandler(final FileBased obj, final FileLocator locator) {
content = obj;
fileLocator = new AtomicReference<>(locator);
}
/**
* Adds a listener to this {@code FileHandler}. It is notified about property changes and IO operations.
*
* @param l the listener to be added (must not be <b>null</b>)
* @throws IllegalArgumentException if the listener is <b>null</b>
*/
public void addFileHandlerListener(final FileHandlerListener l) {
if (l == null) {
throw new IllegalArgumentException("Listener must not be null!");
}
listeners.add(l);
}
/**
* Checks whether a content object is available. If not, an exception is thrown. This method is called whenever the
* content object is accessed.
*
* @throws ConfigurationException if not content object is defined
*/
private void checkContent() throws ConfigurationException {
if (getContent() == null) {
throw new ConfigurationException("No content available!");
}
}
/**
* Checks whether a content object is available and returns the current {@code FileLocator}. If there is no content
* object, an exception is thrown. This is a typical operation to be performed before a load() or save() operation.
*
* @return the current {@code FileLocator} to be used for the calling operation
* @throws ConfigurationException if not content object is defined
*/
private FileLocator checkContentAndGetLocator() throws ConfigurationException {
checkContent();
return getFileLocator();
}
/**
* Clears the location of this {@code FileHandler}. Afterwards this handler does not point to any valid file.
*/
public void clearLocation() {
new AbstractUpdater() {
@Override
protected void updateBuilder(final FileLocatorBuilder builder) {
builder.basePath(null).fileName(null).sourceURL(null);
}
}.update();
}
/**
* Creates a {@code FileLocator} which is a copy of the passed in one, but has the given file name set to reference the
* target file.
*
* @param fileName the file name
* @param locator the {@code FileLocator} to copy
* @return the manipulated {@code FileLocator} with the file name
*/
private FileLocator createLocatorWithFileName(final String fileName, final FileLocator locator) {
return FileLocatorUtils.fileLocator(locator).sourceURL(null).fileName(fileName).create();
}
/**
* Obtains a {@code SynchronizerSupport} for the current content. If the content implements this interface, it is
* returned. Otherwise, result is a dummy object. This method is called before load and save operations. The returned
* object is used for synchronization.
*
* @return the {@code SynchronizerSupport} for synchronization
*/
private SynchronizerSupport fetchSynchronizerSupport() {
if (getContent() instanceof SynchronizerSupport) {
return (SynchronizerSupport) getContent();
}
return DUMMY_SYNC_SUPPORT;
}
/**
* Notifies the registered listeners about a completed load operation.
*/
private void fireLoadedEvent() {
listeners.forEach(l -> l.loaded(this));
}
/**
* Notifies the registered listeners about the start of a load operation.
*/
private void fireLoadingEvent() {
listeners.forEach(l -> l.loading(this));
}
/**
* Notifies the registered listeners about a property update.
*/
private void fireLocationChangedEvent() {
listeners.forEach(l -> l.locationChanged(this));
}
/**
* Notifies the registered listeners about a completed save operation.
*/
private void fireSavedEvent() {
listeners.forEach(l -> l.saved(this));
}
/**
* Notifies the registered listeners about the start of a save operation.
*/
private void fireSavingEvent() {
listeners.forEach(l -> l.saving(this));
}
/**
* Gets the base path. If no base path is defined, but a URL, the base path is derived from there.
*
* @return the base path
*/
public String getBasePath() {
final FileLocator locator = getFileLocator();
if (locator.getBasePath() != null) {
return locator.getBasePath();
}
if (locator.getSourceURL() != null) {
return FileLocatorUtils.getBasePath(locator.getSourceURL());
}
return null;
}
/**
* Gets the {@code FileBased} object associated with this {@code FileHandler}.
*
* @return the associated {@code FileBased} object
*/
public final FileBased getContent() {
return content;
}
/**
* Gets the encoding of the associated file. Result can be <b>null</b> if no encoding has been set.
*
* @return the encoding of the associated file
*/
public String getEncoding() {
return getFileLocator().getEncoding();
}
/**
* Gets the location of the associated file as a {@code File} object. If the base path is a URL with a protocol
* different than "file", or the file is within a compressed archive, the return value will not point to a
* valid file object.
*
* @return the location as {@code File} object; this can be <b>null</b>
*/
public File getFile() {
return createFile(getFileLocator());
}
/**
* Gets a {@code FileLocator} object with the specification of the file stored by this {@code FileHandler}. Note that
* this method returns the internal data managed by this {@code FileHandler} as it was defined. This is not necessarily
* the same as the data returned by the single access methods like {@code getFileName()} or {@code getURL()}: These
* methods try to derive missing data from other values that have been set.
*
* @return a {@code FileLocator} with the referenced file
*/
public FileLocator getFileLocator() {
return fileLocator.get();
}
/**
* Gets the name of the file. If only a URL is defined, the file name is derived from there.
*
* @return the file name
*/
public String getFileName() {
final FileLocator locator = getFileLocator();
if (locator.getFileName() != null) {
return locator.getFileName();
}
if (locator.getSourceURL() != null) {
return FileLocatorUtils.getFileName(locator.getSourceURL());
}
return null;
}
/**
* Gets the {@code FileSystem} to be used by this object when locating files. Result is never <b>null</b>; if no file
* system has been set, the default file system is returned.
*
* @return the used {@code FileSystem}
*/
public FileSystem getFileSystem() {
return FileLocatorUtils.getFileSystem(getFileLocator());
}
/**
* Gets the {@code FileLocationStrategy} to be applied when accessing the associated file. This method never returns
* <b>null</b>. If a {@code FileLocationStrategy} has been set, it is returned. Otherwise, result is the default
* {@code FileLocationStrategy}.
*
* @return the {@code FileLocationStrategy} to be used
*/
public FileLocationStrategy getLocationStrategy() {
return FileLocatorUtils.getLocationStrategy(getFileLocator());
}
/**
* Gets the full path to the associated file. The return value is a valid {@code File} path only if this location is
* based on a file on the local disk. If the file was loaded from a packed archive, the returned value is the string
* form of the URL from which the file was loaded.
*
* @return the full path to the associated file
*/
public String getPath() {
final FileLocator locator = getFileLocator();
final File file = createFile(locator);
return FileLocatorUtils.getFileSystem(locator).getPath(file, locator.getSourceURL(), locator.getBasePath(), locator.getFileName());
}
/**
* Gets the location of the associated file as a URL. If a URL is set, it is directly returned. Otherwise, an attempt
* to locate the referenced file is made.
*
* @return a URL to the associated file; can be <b>null</b> if the location is unspecified
*/
public URL getURL() {
final FileLocator locator = getFileLocator();
return locator.getSourceURL() != null ? locator.getSourceURL() : FileLocatorUtils.locate(locator);
}
/**
* Injects a {@code FileLocator} pointing to the specified URL if the current {@code FileBased} object implements the
* {@code FileLocatorAware} interface.
*
* @param url the URL for the locator
*/
private void injectFileLocator(final URL url) {
if (url == null) {
injectNullFileLocator();
} else if (getContent() instanceof FileLocatorAware) {
final FileLocator locator = prepareNullLocatorBuilder().sourceURL(url).create();
((FileLocatorAware) getContent()).initFileLocator(locator);
}
}
/**
* Checks whether the associated {@code FileBased} object implements the {@code FileLocatorAware} interface. If this is
* the case, a {@code FileLocator} instance is injected which returns only <b>null</b> values. This method is called if
* no file location is available (e.g. if data is to be loaded from a stream). The encoding of the injected locator is
* derived from this object.
*/
private void injectNullFileLocator() {
if (getContent() instanceof FileLocatorAware) {
final FileLocator locator = prepareNullLocatorBuilder().create();
((FileLocatorAware) getContent()).initFileLocator(locator);
}
}
/**
* Tests whether a location is defined for this {@code FileHandler}.
*
* @return <b>true</b> if a location is defined, <b>false</b> otherwise
*/
public boolean isLocationDefined() {
return FileLocatorUtils.isLocationDefined(getFileLocator());
}
/**
* Loads the associated file from the underlying location. If no location has been set, an exception is thrown.
*
* @throws ConfigurationException if loading of the configuration fails
*/
public void load() throws ConfigurationException {
load(checkContentAndGetLocator());
}
/**
* Loads the associated file from the specified {@code File}.
*
* @param file the file to load
* @throws ConfigurationException if an error occurs
*/
public void load(final File file) throws ConfigurationException {
final URL url;
try {
url = FileLocatorUtils.toURL(file);
} catch (final MalformedURLException e1) {
throw new ConfigurationException("Cannot create URL from file " + file);
}
load(url);
}
/**
* Internal helper method for loading the associated file from the location specified in the given {@code FileLocator}.
*
* @param locator the current {@code FileLocator}
* @throws ConfigurationException if an error occurs
*/
private void load(final FileLocator locator) throws ConfigurationException {
load(FileLocatorUtils.locateOrThrow(locator), locator);
}
/**
* Loads the associated file from the specified stream, using the encoding returned by {@link #getEncoding()}.
*
* @param in the input stream
* @throws ConfigurationException if an error occurs during the load operation
*/
public void load(final InputStream in) throws ConfigurationException {
load(in, checkContentAndGetLocator());
}
/**
* Internal helper method for loading a file from the given input stream.
*
* @param in the input stream
* @param locator the current {@code FileLocator}
* @throws ConfigurationException if an error occurs
*/
private void load(final InputStream in, final FileLocator locator) throws ConfigurationException {
load(in, locator.getEncoding());
}
/**
* Loads the associated file from the specified stream, using the specified encoding. If the encoding is <b>null</b>,
* the default encoding is used.
*
* @param in the input stream
* @param encoding the encoding used, {@code null} to use the default encoding
* @throws ConfigurationException if an error occurs during the load operation
*/
public void load(final InputStream in, final String encoding) throws ConfigurationException {
loadFromStream(in, encoding, null);
}
/**
* Loads the associated file from the specified reader.
*
* @param in the reader
* @throws ConfigurationException if an error occurs during the load operation
*/
public void load(final Reader in) throws ConfigurationException {
checkContent();
injectNullFileLocator();
loadFromReader(in);
}
/**
* Loads the associated file from the given file name. The file name is interpreted in the context of the already set
* location (e.g. if it is a relative file name, a base path is applied if available). The underlying location is not
* changed.
*
* @param fileName the name of the file to be loaded
* @throws ConfigurationException if an error occurs
*/
public void load(final String fileName) throws ConfigurationException {
load(fileName, checkContentAndGetLocator());
}
/**
* Internal helper method for loading a file from a file name.
*
* @param fileName the file name
* @param locator the current {@code FileLocator}
* @throws ConfigurationException if an error occurs
*/
private void load(final String fileName, final FileLocator locator) throws ConfigurationException {
final FileLocator locFileName = createLocatorWithFileName(fileName, locator);
final URL url = FileLocatorUtils.locateOrThrow(locFileName);
load(url, locator);
}
/**
* Loads the associated file from the specified URL. The location stored in this object is not changed.
*
* @param url the URL of the file to be loaded
* @throws ConfigurationException if an error occurs
*/
public void load(final URL url) throws ConfigurationException {
load(url, checkContentAndGetLocator());
}
/**
* Internal helper method for loading a file from the given URL.
*
* @param url the URL
* @param locator the current {@code FileLocator}
* @throws ConfigurationException if an error occurs
*/
private void load(final URL url, final FileLocator locator) throws ConfigurationException {
InputStream in = null;
try {
final FileSystem fileSystem = FileLocatorUtils.getFileSystem(locator);
final URLConnectionOptions urlConnectionOptions = locator.getURLConnectionOptions();
in = urlConnectionOptions == null ? fileSystem.getInputStream(url) : fileSystem.getInputStream(url, urlConnectionOptions);
loadFromStream(in, locator.getEncoding(), url);
} catch (final ConfigurationException e) {
throw e;
} catch (final Exception e) {
throw new ConfigurationException("Unable to load the configuration from the URL " + url, e);
} finally {
closeSilent(in);
}
}
/**
* Internal helper method for loading a file from the given reader.
*
* @param in the reader
* @throws ConfigurationException if an error occurs
*/
private void loadFromReader(final Reader in) throws ConfigurationException {
fireLoadingEvent();
try {
getContent().read(in);
} catch (final IOException ioex) {
throw new ConfigurationException(ioex);
} finally {
fireLoadedEvent();
}
}
/**
* Internal helper method for loading a file from an input stream.
*
* @param in the input stream
* @param encoding the encoding
* @param url the URL of the file to be loaded (if known)
* @throws ConfigurationException if an error occurs
*/
private void loadFromStream(final InputStream in, final String encoding, final URL url) throws ConfigurationException {
checkContent();
final SynchronizerSupport syncSupport = fetchSynchronizerSupport();
syncSupport.lock(LockMode.WRITE);
try {
injectFileLocator(url);
if (getContent() instanceof InputStreamSupport) {
loadFromStreamDirectly(in);
} else {
loadFromTransformedStream(in, encoding);
}
} finally {
syncSupport.unlock(LockMode.WRITE);
}
}
/**
* Loads data from an input stream if the associated {@code FileBased} object implements the {@code InputStreamSupport}
* interface.
*
* @param in the input stream
* @throws ConfigurationException if an error occurs
*/
private void loadFromStreamDirectly(final InputStream in) throws ConfigurationException {
try {
((InputStreamSupport) getContent()).read(in);
} catch (final IOException e) {
throw new ConfigurationException(e);
}
}
/**
* Internal helper method for transforming an input stream to a reader and reading its content.
*
* @param in the input stream
* @param encoding the encoding
* @throws ConfigurationException if an error occurs
*/
private void loadFromTransformedStream(final InputStream in, final String encoding) throws ConfigurationException {
Reader reader = null;
if (encoding != null) {
try {
reader = new InputStreamReader(in, encoding);
} catch (final UnsupportedEncodingException e) {
throw new ConfigurationException("The requested encoding is not supported, try the default encoding.", e);
}
}
if (reader == null) {
reader = new InputStreamReader(in);
}
loadFromReader(reader);
}
/**
* Locates the referenced file if necessary and ensures that the associated {@link FileLocator} is fully initialized.
* When accessing the referenced file the information stored in the associated {@code FileLocator} is used. If this
* information is incomplete (e.g. only the file name is set), an attempt to locate the file may have to be performed on
* each access. By calling this method such an attempt is performed once, and the results of a successful localization
* are stored. Hence, later access to the referenced file can be more efficient. Also, all properties pointing to the
* referenced file in this object's {@code FileLocator} are set (i.e. the URL, the base path, and the file name). If the
* referenced file cannot be located, result is <b>false</b>. This means that the information in the current
* {@code FileLocator} is insufficient or wrong. If the {@code FileLocator} is already fully defined, it is not changed.
*
* @return a flag whether the referenced file could be located successfully
* @see FileLocatorUtils#fullyInitializedLocator(FileLocator)
*/
public boolean locate() {
boolean result;
boolean done;
do {
final FileLocator locator = getFileLocator();
FileLocator fullLocator = FileLocatorUtils.fullyInitializedLocator(locator);
if (fullLocator == null) {
result = false;
fullLocator = locator;
} else {
result = fullLocator != locator || FileLocatorUtils.isFullyInitialized(locator);
}
done = fileLocator.compareAndSet(locator, fullLocator);
} while (!done);
return result;
}
/**
* Prepares a builder for a {@code FileLocator} which does not have a defined file location. Other properties (e.g.
* encoding or file system) are initialized from the {@code FileLocator} associated with this object.
*
* @return the initialized builder for a {@code FileLocator}
*/
private FileLocatorBuilder prepareNullLocatorBuilder() {
return FileLocatorUtils.fileLocator(getFileLocator()).sourceURL(null).basePath(null).fileName(null);
}
/**
* Removes the specified listener from this object.
*
* @param l the listener to be removed
*/
public void removeFileHandlerListener(final FileHandlerListener l) {
listeners.remove(l);
}
/**
* Resets the {@code FileSystem} used by this object. It is set to the default file system.
*/
public void resetFileSystem() {
setFileSystem(null);
}
/**
* Saves the associated file to the current location set for this object. Before this method can be called a valid
* location must have been set.
*
* @throws ConfigurationException if an error occurs or no location has been set yet
*/
public void save() throws ConfigurationException {
save(checkContentAndGetLocator());
}
/**
* Saves the associated file to the specified {@code File}. The file is created automatically if it doesn't exist. This
* does not change the location of this object (use {@link #setFile} if you need it).
*
* @param file the target file
* @throws ConfigurationException if an error occurs during the save operation
*/
public void save(final File file) throws ConfigurationException {
save(file, checkContentAndGetLocator());
}
/**
* Internal helper method for saving data to the given {@code File}.
*
* @param file the target file
* @param locator the current {@code FileLocator}
* @throws ConfigurationException if an error occurs during the save operation
*/
private void save(final File file, final FileLocator locator) throws ConfigurationException {
OutputStream out = null;
try {
out = FileLocatorUtils.getFileSystem(locator).getOutputStream(file);
saveToStream(out, locator.getEncoding(), file.toURI().toURL());
} catch (final MalformedURLException muex) {
throw new ConfigurationException(muex);
} finally {
closeSilent(out);
}
}
/**
* Internal helper method for saving data to the internal location stored for this object.
*
* @param locator the current {@code FileLocator}
* @throws ConfigurationException if an error occurs during the save operation
*/
private void save(final FileLocator locator) throws ConfigurationException {
if (!FileLocatorUtils.isLocationDefined(locator)) {
throw new ConfigurationException("No file location has been set!");
}
if (locator.getSourceURL() != null) {
save(locator.getSourceURL(), locator);
} else {
save(locator.getFileName(), locator);
}
}
/**
* Saves the associated file to the specified stream using the encoding returned by {@link #getEncoding()}.
*
* @param out the output stream
* @throws ConfigurationException if an error occurs during the save operation
*/
public void save(final OutputStream out) throws ConfigurationException {
save(out, checkContentAndGetLocator());
}
/**
* Internal helper method for saving a file to the given output stream.
*
* @param out the output stream
* @param locator the current {@code FileLocator}
* @throws ConfigurationException if an error occurs during the save operation
*/
private void save(final OutputStream out, final FileLocator locator) throws ConfigurationException {
save(out, locator.getEncoding());
}
/**
* Saves the associated file to the specified stream using the specified encoding. If the encoding is <b>null</b>, the
* default encoding is used.
*
* @param out the output stream
* @param encoding the encoding to be used, {@code null} to use the default encoding
* @throws ConfigurationException if an error occurs during the save operation
*/
public void save(final OutputStream out, final String encoding) throws ConfigurationException {
saveToStream(out, encoding, null);
}
/**
* Saves the associated file to the specified file name. This does not change the location of this object (use
* {@link #setFileName(String)} if you need it).
*
* @param fileName the file name
* @throws ConfigurationException if an error occurs during the save operation
*/
public void save(final String fileName) throws ConfigurationException {
save(fileName, checkContentAndGetLocator());
}
/**
* Internal helper method for saving data to the given file name.
*
* @param fileName the path to the target file
* @param locator the current {@code FileLocator}
* @throws ConfigurationException if an error occurs during the save operation
*/
private void save(final String fileName, final FileLocator locator) throws ConfigurationException {
final URL url;
try {
url = FileLocatorUtils.getFileSystem(locator).getURL(locator.getBasePath(), fileName);
} catch (final MalformedURLException e) {
throw new ConfigurationException(e);
}
if (url == null) {
throw new ConfigurationException("Cannot locate configuration source " + fileName);
}
save(url, locator);
}
/**
* Saves the associated file to the specified URL. This does not change the location of this object (use
* {@link #setURL(URL)} if you need it).
*
* @param url the URL
* @throws ConfigurationException if an error occurs during the save operation
*/
public void save(final URL url) throws ConfigurationException {
save(url, checkContentAndGetLocator());
}
/**
* Internal helper method for saving data to the given URL.
*
* @param url the target URL
* @param locator the {@code FileLocator}
* @throws ConfigurationException if an error occurs during the save operation
*/
private void save(final URL url, final FileLocator locator) throws ConfigurationException {
OutputStream out = null;
try {
out = FileLocatorUtils.getFileSystem(locator).getOutputStream(url);
saveToStream(out, locator.getEncoding(), url);
if (out instanceof VerifiableOutputStream) {
try {
((VerifiableOutputStream) out).verify();
} catch (final IOException e) {
throw new ConfigurationException(e);
}
}
} finally {
closeSilent(out);
}
}
/**
* Saves the associated file to the given {@code Writer}.
*
* @param out the {@code Writer}
* @throws ConfigurationException if an error occurs during the save operation
*/
public void save(final Writer out) throws ConfigurationException {
checkContent();
injectNullFileLocator();
saveToWriter(out);
}
/**
* Internal helper method for saving a file to the given stream.
*
* @param out the output stream
* @param encoding the encoding
* @param url the URL of the output file if known
* @throws ConfigurationException if an error occurs
*/
private void saveToStream(final OutputStream out, final String encoding, final URL url) throws ConfigurationException {
checkContent();
final SynchronizerSupport syncSupport = fetchSynchronizerSupport();
syncSupport.lock(LockMode.WRITE);
try {
injectFileLocator(url);
Writer writer = null;
if (encoding != null) {
try {
writer = new OutputStreamWriter(out, encoding);
} catch (final UnsupportedEncodingException e) {
throw new ConfigurationException("The requested encoding is not supported, try the default encoding.", e);
}
}
if (writer == null) {
writer = new OutputStreamWriter(out);
}
saveToWriter(writer);
} finally {
syncSupport.unlock(LockMode.WRITE);
}
}
/**
* Internal helper method for saving a file into the given writer.
*
* @param out the writer
* @throws ConfigurationException if an error occurs
*/
private void saveToWriter(final Writer out) throws ConfigurationException {
fireSavingEvent();
try {
getContent().write(out);
} catch (final IOException ioex) {
throw new ConfigurationException(ioex);
} finally {
fireSavedEvent();
}
}
/**
* Sets the base path. The base path is typically either a path to a directory or a URL. Together with the value passed
* to the {@code setFileName()} method it defines the location of the configuration file to be loaded. The strategies
* for locating the file are quite tolerant. For instance if the file name is already an absolute path or a fully
* defined URL, the base path will be ignored. The base path can also be a URL, in which case the file name is
* interpreted in this URL's context. If other methods are used for determining the location of the associated file
* (e.g. {@code setFile()} or {@code setURL()}), the base path is automatically set. Setting the base path using this
* method automatically sets the URL to <b>null</b> because it has to be determined anew based on the file name and the
* base path.
*
* @param basePath the base path.
*/
public void setBasePath(final String basePath) {
final String path = normalizeFileURL(basePath);
new AbstractUpdater() {
@Override
protected void updateBuilder(final FileLocatorBuilder builder) {
builder.basePath(path);
builder.sourceURL(null);
}
}.update();
}
/**
* Sets the encoding of the associated file. The encoding applies if binary files are loaded. Note that in this case
* setting an encoding is recommended; otherwise the platform's default encoding is used.
*
* @param encoding the encoding of the associated file
*/
public void setEncoding(final String encoding) {
new AbstractUpdater() {
@Override
protected void updateBuilder(final FileLocatorBuilder builder) {
builder.encoding(encoding);
}
}.update();
}
/**
* Sets the location of the associated file as a {@code File} object. The passed in {@code File} is made absolute if it
* is not yet. Then the file's path component becomes the base path and its name component becomes the file name.
*
* @param file the location of the associated file
*/
public void setFile(final File file) {
final String fileName = file.getName();
final String basePath = file.getParentFile() != null ? file.getParentFile().getAbsolutePath() : null;
new AbstractUpdater() {
@Override
protected void updateBuilder(final FileLocatorBuilder builder) {
builder.fileName(fileName).basePath(basePath).sourceURL(null);
}
}.update();
}
/**
* Sets the file to be accessed by this {@code FileHandler} as a {@code FileLocator} object.
*
* @param locator the {@code FileLocator} with the definition of the file to be accessed (must not be <b>null</b>
* @throws IllegalArgumentException if the {@code FileLocator} is <b>null</b>
*/
public void setFileLocator(final FileLocator locator) {
if (locator == null) {
throw new IllegalArgumentException("FileLocator must not be null!");
}
fileLocator.set(locator);
fireLocationChangedEvent();
}
/**
* Sets the name of the file. The passed in file name can contain a relative path. It must be used when referring files
* with relative paths from classpath. Use {@code setPath()} to set a full qualified file name. The URL is set to
* <b>null</b> as it has to be determined anew based on the file name and the base path.
*
* @param fileName the name of the file
*/
public void setFileName(final String fileName) {
final String name = normalizeFileURL(fileName);
new AbstractUpdater() {
@Override
protected void updateBuilder(final FileLocatorBuilder builder) {
builder.fileName(name);
builder.sourceURL(null);
}
}.update();
}
/**
* Sets the {@code FileSystem} to be used by this object when locating files. If a <b>null</b> value is passed in, the
* file system is reset to the default file system.
*
* @param fileSystem the {@code FileSystem}
*/
public void setFileSystem(final FileSystem fileSystem) {
new AbstractUpdater() {
@Override
protected void updateBuilder(final FileLocatorBuilder builder) {
builder.fileSystem(fileSystem);
}
}.update();
}
/**
* Sets the {@code FileLocationStrategy} to be applied when accessing the associated file. The strategy is stored in the
* underlying {@link FileLocator}. The argument can be <b>null</b>; this causes the default {@code FileLocationStrategy}
* to be used.
*
* @param strategy the {@code FileLocationStrategy}
* @see FileLocatorUtils#DEFAULT_LOCATION_STRATEGY
*/
public void setLocationStrategy(final FileLocationStrategy strategy) {
new AbstractUpdater() {
@Override
protected void updateBuilder(final FileLocatorBuilder builder) {
builder.locationStrategy(strategy);
}
}.update();
}
/**
* Sets the location of the associated file as a full or relative path name. The passed in path should represent a valid
* file name on the file system. It must not be used to specify relative paths for files that exist in classpath, either
* plain file system or compressed archive, because this method expands any relative path to an absolute one which may
* end in an invalid absolute path for classpath references.
*
* @param path the full path name of the associated file
*/
public void setPath(final String path) {
setFile(new File(path));
}
/**
* Sets the location of the associated file as a URL. For loading this can be an arbitrary URL with a supported
* protocol. If the file is to be saved, too, a URL with the "file" protocol should be provided. This method
* sets the file name and the base path to <b>null</b>. They have to be determined anew based on the new URL.
*
* @param url the location of the file as URL
*/
public void setURL(final URL url) {
setURL(url, URLConnectionOptions.DEFAULT);
}
/**
* Sets the location of the associated file as a URL. For loading this can be an arbitrary URL with a supported
* protocol. If the file is to be saved, too, a URL with the "file" protocol should be provided. This method
* sets the file name and the base path to <b>null</b>. They have to be determined anew based on the new URL.
*
* @param url the location of the file as URL
* @param urlConnectionOptions URL connection options
* @since 2.8.0
*/
public void setURL(final URL url, final URLConnectionOptions urlConnectionOptions) {
new AbstractUpdater() {
@Override
protected void updateBuilder(final FileLocatorBuilder builder) {
builder.sourceURL(url);
builder.urlConnectionOptions(urlConnectionOptions);
builder.basePath(null).fileName(null);
}
}.update();
}
}