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.File;
020import java.net.MalformedURLException;
021import java.net.URI;
022import java.net.URL;
023import java.util.Arrays;
024import java.util.Map;
025
026import org.apache.commons.configuration2.ex.ConfigurationException;
027import org.apache.commons.lang3.ObjectUtils;
028import org.apache.commons.lang3.StringUtils;
029import org.apache.commons.logging.Log;
030import org.apache.commons.logging.LogFactory;
031
032/**
033 * <p>
034 * A utility class providing helper methods related to locating files.
035 * </p>
036 * <p>
037 * The methods of this class are used behind the scenes when retrieving
038 * configuration files based on different criteria, e.g. URLs, files, or more
039 * complex search strategies. They also implement functionality required by the
040 * default {@link FileSystem} implementations. Most methods are intended to be
041 * used internally only by other classes in the {@code io} package.
042 * </p>
043 *
044 * @version $Id: FileLocatorUtils.java 1750126 2016-06-24 15:49:12Z oheger $
045 * @since 2.0
046 */
047public final class FileLocatorUtils
048{
049    /**
050     * Constant for the default {@code FileSystem}. This file system is used by
051     * operations of this class if no specific file system is provided. An
052     * instance of {@link DefaultFileSystem} is used.
053     */
054    public static final FileSystem DEFAULT_FILE_SYSTEM =
055            new DefaultFileSystem();
056
057    /**
058     * Constant for the default {@code FileLocationStrategy}. This strategy is
059     * used by the {@code locate()} method if the passed in {@code FileLocator}
060     * does not define its own location strategy. The default location strategy
061     * is roughly equivalent to the search algorithm used in version 1.x of
062     * <em>Commons Configuration</em> (there it was hard-coded though). It
063     * behaves in the following way when passed a {@code FileLocator}:
064     * <ul>
065     * <li>If the {@code FileLocator} has a defined URL, this URL is used as the
066     * file's URL (without any further checks).</li>
067     * <li>Otherwise, base path and file name stored in the {@code FileLocator}
068     * are passed to the current {@code FileSystem}'s {@code locateFromURL()}
069     * method. If this results in a URL, it is returned.</li>
070     * <li>Otherwise, if the locator's file name is an absolute path to an
071     * existing file, the URL of this file is returned.</li>
072     * <li>Otherwise, the concatenation of base path and file name is
073     * constructed. If this path points to an existing file, its URL is
074     * returned.</li>
075     * <li>Otherwise, a sub directory of the current user's home directory as
076     * defined by the base path is searched for the referenced file. If the file
077     * can be found there, its URL is returned.</li>
078     * <li>Otherwise, the base path is ignored, and the file name is searched in
079     * the current user's home directory. If the file can be found there, its
080     * URL is returned.</li>
081     * <li>Otherwise, a resource with the name of the locator's file name is
082     * searched in the classpath. If it can be found, its URL is returned.</li>
083     * <li>Otherwise, the strategy gives up and returns <b>null</b> indicating
084     * that the file cannot be resolved.</li>
085     * </ul>
086     */
087    public static final FileLocationStrategy DEFAULT_LOCATION_STRATEGY =
088            initDefaultLocationStrategy();
089
090    /** Constant for the file URL protocol */
091    private static final String FILE_SCHEME = "file:";
092
093    /** The logger.*/
094    private static final Log LOG = LogFactory.getLog(FileLocatorUtils.class);
095
096    /** Property key for the base path. */
097    private static final String PROP_BASE_PATH = "basePath";
098
099    /** Property key for the encoding. */
100    private static final String PROP_ENCODING = "encoding";
101
102    /** Property key for the file name. */
103    private static final String PROP_FILE_NAME = "fileName";
104
105    /** Property key for the file system. */
106    private static final String PROP_FILE_SYSTEM = "fileSystem";
107
108    /** Property key for the location strategy. */
109    private static final String PROP_STRATEGY = "locationStrategy";
110
111    /** Property key for the source URL. */
112    private static final String PROP_SOURCE_URL = "sourceURL";
113
114    /**
115     * Private constructor so that no instances can be created.
116     */
117    private FileLocatorUtils()
118    {
119    }
120
121    /**
122     * Tries to convert the specified URL to a file object. If this fails,
123     * <b>null</b> is returned.
124     *
125     * @param url the URL
126     * @return the resulting file object
127     */
128    public static File fileFromURL(URL url)
129    {
130        return FileUtils.toFile(url);
131    }
132
133    /**
134     * Returns an uninitialized {@code FileLocatorBuilder} which can be used
135     * for the creation of a {@code FileLocator} object. This method provides
136     * a convenient way to create file locators using a fluent API as in the
137     * following example:
138     * <pre>
139     * FileLocator locator = FileLocatorUtils.fileLocator()
140     *     .basePath(myBasePath)
141     *     .fileName("test.xml")
142     *     .create();
143     * </pre>
144     * @return a builder object for defining a {@code FileLocator}
145     */
146    public static FileLocator.FileLocatorBuilder fileLocator()
147    {
148        return fileLocator(null);
149    }
150
151    /**
152     * Returns a {@code FileLocatorBuilder} which is already initialized with
153     * the properties of the passed in {@code FileLocator}. This builder can
154     * be used to create a {@code FileLocator} object which shares properties
155     * of the original locator (e.g. the {@code FileSystem} or the encoding),
156     * but points to a different file. An example use case is as follows:
157     * <pre>
158     * FileLocator loc1 = ...
159     * FileLocator loc2 = FileLocatorUtils.fileLocator(loc1)
160     *     .setFileName("anotherTest.xml")
161     *     .create();
162     * </pre>
163     * @param src the source {@code FileLocator} (may be <b>null</b>)
164     * @return an initialized builder object for defining a {@code FileLocator}
165     */
166    public static FileLocator.FileLocatorBuilder fileLocator(FileLocator src)
167    {
168        return new FileLocator.FileLocatorBuilder(src);
169    }
170
171    /**
172     * Creates a new {@code FileLocator} object with the properties defined in
173     * the given map. The map must be conform to the structure generated by the
174     * {@link #put(FileLocator, Map)} method; unexpected data can cause
175     * {@code ClassCastException} exceptions. The map can be <b>null</b>, then
176     * an uninitialized {@code FileLocator} is returned.
177     *
178     * @param map the map
179     * @return the new {@code FileLocator}
180     * @throws ClassCastException if the map contains invalid data
181     */
182    public static FileLocator fromMap(Map<String, ?> map)
183    {
184        FileLocator.FileLocatorBuilder builder = fileLocator();
185        if (map != null)
186        {
187            builder.basePath((String) map.get(PROP_BASE_PATH))
188                    .encoding((String) map.get(PROP_ENCODING))
189                    .fileName((String) map.get(PROP_FILE_NAME))
190                    .fileSystem((FileSystem) map.get(PROP_FILE_SYSTEM))
191                    .locationStrategy(
192                            (FileLocationStrategy) map.get(PROP_STRATEGY))
193                    .sourceURL((URL) map.get(PROP_SOURCE_URL));
194        }
195        return builder.create();
196    }
197
198    /**
199     * Stores the specified {@code FileLocator} in the given map. With the
200     * {@link #fromMap(Map)} method a new {@code FileLocator} with the same
201     * properties as the original one can be created.
202     *
203     * @param locator the {@code FileLocator} to be stored
204     * @param map the map in which to store the {@code FileLocator} (must not be
205     *        <b>null</b>)
206     * @throws IllegalArgumentException if the map is <b>null</b>
207     */
208    public static void put(FileLocator locator, Map<String, Object> map)
209    {
210        if (map == null)
211        {
212            throw new IllegalArgumentException("Map must not be null!");
213        }
214
215        if (locator != null)
216        {
217            map.put(PROP_BASE_PATH, locator.getBasePath());
218            map.put(PROP_ENCODING, locator.getEncoding());
219            map.put(PROP_FILE_NAME, locator.getFileName());
220            map.put(PROP_FILE_SYSTEM, locator.getFileSystem());
221            map.put(PROP_SOURCE_URL, locator.getSourceURL());
222            map.put(PROP_STRATEGY, locator.getLocationStrategy());
223        }
224    }
225
226    /**
227     * Checks whether the specified {@code FileLocator} contains enough
228     * information to locate a file. This is the case if a file name or a URL is
229     * defined. If the passed in {@code FileLocator} is <b>null</b>, result is
230     * <b>false</b>.
231     *
232     * @param locator the {@code FileLocator} to check
233     * @return a flag whether a file location is defined by this
234     *         {@code FileLocator}
235     */
236    public static boolean isLocationDefined(FileLocator locator)
237    {
238        return (locator != null)
239                && (locator.getFileName() != null || locator.getSourceURL() != null);
240    }
241
242    /**
243     * Returns a flag whether all components of the given {@code FileLocator}
244     * describing the referenced file are defined. In order to reference a file,
245     * it is not necessary that all components are filled in (for instance, the
246     * URL alone is sufficient). For some use cases however, it might be of
247     * interest to have different methods for accessing the referenced file.
248     * Also, depending on the filled out properties, there is a subtle
249     * difference how the file is accessed: If only the file name is set (and
250     * optionally the base path), each time the file is accessed a
251     * {@code locate()} operation has to be performed to uniquely identify the
252     * file. If however the URL is determined once based on the other components
253     * and stored in a fully defined {@code FileLocator}, it can be used
254     * directly to identify the file. If the passed in {@code FileLocator} is
255     * <b>null</b>, result is <b>false</b>.
256     *
257     * @param locator the {@code FileLocator} to be checked (may be <b>null</b>)
258     * @return a flag whether all components describing the referenced file are
259     *         initialized
260     */
261    public static boolean isFullyInitialized(FileLocator locator)
262    {
263        if (locator == null)
264        {
265            return false;
266        }
267        return locator.getBasePath() != null && locator.getFileName() != null
268                && locator.getSourceURL() != null;
269    }
270
271    /**
272     * Returns a {@code FileLocator} object based on the passed in one whose
273     * location is fully defined. This method ensures that all components of the
274     * {@code FileLocator} pointing to the file are set in a consistent way. In
275     * detail it behaves as follows:
276     * <ul>
277     * <li>If the {@code FileLocator} has already all components set which
278     * define the file, it is returned unchanged. <em>Note:</em> It is not
279     * checked whether all components are really consistent!</li>
280     * <li>{@link #locate(FileLocator)} is called to determine a unique URL
281     * pointing to the referenced file. If this is successful, a new
282     * {@code FileLocator} is created as a copy of the passed in one, but with
283     * all components pointing to the file derived from this URL.</li>
284     * <li>Otherwise, result is <b>null</b>.</li>
285     * </ul>
286     *
287     * @param locator the {@code FileLocator} to be completed
288     * @return a {@code FileLocator} with a fully initialized location if
289     *         possible or <b>null</b>
290     */
291    public static FileLocator fullyInitializedLocator(FileLocator locator)
292    {
293        if (isFullyInitialized(locator))
294        {
295            // already fully initialized
296            return locator;
297        }
298
299        URL url = locate(locator);
300        return (url != null) ? createFullyInitializedLocatorFromURL(locator,
301                url) : null;
302    }
303
304    /**
305     * Locates the provided {@code FileLocator}, returning a URL for accessing
306     * the referenced file. This method uses a {@link FileLocationStrategy} to
307     * locate the file the passed in {@code FileLocator} points to. If the
308     * {@code FileLocator} contains itself a {@code FileLocationStrategy}, it is
309     * used. Otherwise, the default {@code FileLocationStrategy} is applied. The
310     * strategy is passed the locator and a {@code FileSystem}. The resulting
311     * URL is returned. If the {@code FileLocator} is <b>null</b>, result is
312     * <b>null</b>.
313     *
314     * @param locator the {@code FileLocator} to be resolved
315     * @return the URL pointing to the referenced file or <b>null</b> if the
316     *         {@code FileLocator} could not be resolved
317     * @see #DEFAULT_LOCATION_STRATEGY
318     */
319    public static URL locate(FileLocator locator)
320    {
321        if (locator == null)
322        {
323            return null;
324        }
325
326        return obtainLocationStrategy(locator).locate(
327                obtainFileSystem(locator), locator);
328    }
329
330    /**
331     * Tries to locate the file referenced by the passed in {@code FileLocator}.
332     * If this fails, an exception is thrown. This method works like
333     * {@link #locate(FileLocator)}; however, in case of a failed location
334     * attempt an exception is thrown.
335     *
336     * @param locator the {@code FileLocator} to be resolved
337     * @return the URL pointing to the referenced file
338     * @throws ConfigurationException if the file cannot be resolved
339     */
340    public static URL locateOrThrow(FileLocator locator)
341            throws ConfigurationException
342    {
343        URL url = locate(locator);
344        if (url == null)
345        {
346            throw new ConfigurationException("Could not locate: " + locator);
347        }
348        return url;
349    }
350
351    /**
352     * Return the path without the file name, for example http://xyz.net/foo/bar.xml
353     * results in http://xyz.net/foo/
354     *
355     * @param url the URL from which to extract the path
356     * @return the path component of the passed in URL
357     */
358    static String getBasePath(URL url)
359    {
360        if (url == null)
361        {
362            return null;
363        }
364
365        String s = url.toString();
366        if (s.startsWith(FILE_SCHEME) && !s.startsWith("file://"))
367        {
368            s = "file://" + s.substring(FILE_SCHEME.length());
369        }
370
371        if (s.endsWith("/") || StringUtils.isEmpty(url.getPath()))
372        {
373            return s;
374        }
375        else
376        {
377            return s.substring(0, s.lastIndexOf("/") + 1);
378        }
379    }
380
381    /**
382     * Extract the file name from the specified URL.
383     *
384     * @param url the URL from which to extract the file name
385     * @return the extracted file name
386     */
387    static String getFileName(URL url)
388    {
389        if (url == null)
390        {
391            return null;
392        }
393
394        String path = url.getPath();
395
396        if (path.endsWith("/") || StringUtils.isEmpty(path))
397        {
398            return null;
399        }
400        else
401        {
402            return path.substring(path.lastIndexOf("/") + 1);
403        }
404    }
405
406    /**
407     * Tries to convert the specified base path and file name into a file object.
408     * This method is called e.g. by the save() methods of file based
409     * configurations. The parameter strings can be relative files, absolute
410     * files and URLs as well. This implementation checks first whether the passed in
411     * file name is absolute. If this is the case, it is returned. Otherwise
412     * further checks are performed whether the base path and file name can be
413     * combined to a valid URL or a valid file name. <em>Note:</em> The test
414     * if the passed in file name is absolute is performed using
415     * {@code java.io.File.isAbsolute()}. If the file name starts with a
416     * slash, this method will return <b>true</b> on Unix, but <b>false</b> on
417     * Windows. So to ensure correct behavior for relative file names on all
418     * platforms you should never let relative paths start with a slash. E.g.
419     * in a configuration definition file do not use something like that:
420     * <pre>
421     * &lt;properties fileName="/subdir/my.properties"/&gt;
422     * </pre>
423     * Under Windows this path would be resolved relative to the configuration
424     * definition file. Under Unix this would be treated as an absolute path
425     * name.
426     *
427     * @param basePath the base path
428     * @param fileName the file name (must not be <b>null</b>)
429     * @return the file object (<b>null</b> if no file can be obtained)
430     */
431    static File getFile(String basePath, String fileName)
432    {
433        // Check if the file name is absolute
434        File f = new File(fileName);
435        if (f.isAbsolute())
436        {
437            return f;
438        }
439
440        // Check if URLs are involved
441        URL url;
442        try
443        {
444            url = new URL(new URL(basePath), fileName);
445        }
446        catch (MalformedURLException mex1)
447        {
448            try
449            {
450                url = new URL(fileName);
451            }
452            catch (MalformedURLException mex2)
453            {
454                url = null;
455            }
456        }
457
458        if (url != null)
459        {
460            return fileFromURL(url);
461        }
462
463        return constructFile(basePath, fileName);
464    }
465
466    /**
467     * Convert the specified file into an URL. This method is equivalent
468     * to file.toURI().toURL(). It was used to work around a bug in the JDK
469     * preventing the transformation of a file into an URL if the file name
470     * contains a '#' character. See the issue CONFIGURATION-300 for
471     * more details. Now that we switched to JDK 1.4 we can directly use
472     * file.toURI().toURL().
473     *
474     * @param file the file to be converted into an URL
475     */
476    static URL toURL(File file) throws MalformedURLException
477    {
478        return file.toURI().toURL();
479    }
480
481    /**
482     * Tries to convert the specified URI to a URL. If this causes an exception,
483     * result is <b>null</b>.
484     *
485     * @param uri the URI to be converted
486     * @return the resulting URL or <b>null</b>
487     */
488    static URL convertURIToURL(URI uri)
489    {
490        try
491        {
492            return uri.toURL();
493        }
494        catch (MalformedURLException e)
495        {
496            return null;
497        }
498    }
499
500    /**
501     * Tries to convert the specified file to a URL. If this causes an
502     * exception, result is <b>null</b>.
503     *
504     * @param file the file to be converted
505     * @return the resulting URL or <b>null</b>
506     */
507    static URL convertFileToURL(File file)
508    {
509        return convertURIToURL(file.toURI());
510    }
511
512    /**
513     * Tries to find a resource with the given name in the classpath.
514     *
515     * @param resourceName the name of the resource
516     * @return the URL to the found resource or <b>null</b> if the resource
517     *         cannot be found
518     */
519    static URL locateFromClasspath(String resourceName)
520    {
521        URL url = null;
522        // attempt to load from the context classpath
523        ClassLoader loader = Thread.currentThread().getContextClassLoader();
524        if (loader != null)
525        {
526            url = loader.getResource(resourceName);
527
528            if (url != null)
529            {
530                LOG.debug("Loading configuration from the context classpath (" + resourceName + ")");
531            }
532        }
533
534        // attempt to load from the system classpath
535        if (url == null)
536        {
537            url = ClassLoader.getSystemResource(resourceName);
538
539            if (url != null)
540            {
541                LOG.debug("Loading configuration from the system classpath (" + resourceName + ")");
542            }
543        }
544        return url;
545    }
546
547    /**
548     * Helper method for constructing a file object from a base path and a
549     * file name. This method is called if the base path passed to
550     * {@code getURL()} does not seem to be a valid URL.
551     *
552     * @param basePath the base path
553     * @param fileName the file name (must not be <b>null</b>)
554     * @return the resulting file
555     */
556    static File constructFile(String basePath, String fileName)
557    {
558        File file;
559
560        File absolute = new File(fileName);
561        if (StringUtils.isEmpty(basePath) || absolute.isAbsolute())
562        {
563            file = absolute;
564        }
565        else
566        {
567            file = new File(appendPath(basePath, fileName));
568        }
569
570        return file;
571    }
572
573    /**
574     * Extends a path by another component. The given extension is added to the
575     * already existing path adding a separator if necessary.
576     *
577     * @param path the path to be extended
578     * @param ext the extension of the path
579     * @return the extended path
580     */
581    static String appendPath(String path, String ext)
582    {
583        StringBuilder fName = new StringBuilder();
584        fName.append(path);
585
586        // My best friend. Paranoia.
587        if (!path.endsWith(File.separator))
588        {
589            fName.append(File.separator);
590        }
591
592        //
593        // We have a relative path, and we have
594        // two possible forms here. If we have the
595        // "./" form then just strip that off first
596        // before continuing.
597        //
598        if (ext.startsWith("." + File.separator))
599        {
600            fName.append(ext.substring(2));
601        }
602        else
603        {
604            fName.append(ext);
605        }
606        return fName.toString();
607    }
608
609    /**
610     * Obtains a non-<b>null</b> {@code FileSystem} object from the passed in
611     * {@code FileLocator}. If the passed in {@code FileLocator} has a
612     * {@code FileSystem} object, it is returned. Otherwise, result is the
613     * default {@code FileSystem}.
614     *
615     * @param locator the {@code FileLocator} (may be <b>null</b>)
616     * @return the {@code FileSystem} to be used for this {@code FileLocator}
617     */
618    static FileSystem obtainFileSystem(FileLocator locator)
619    {
620        return (locator != null) ? ObjectUtils.defaultIfNull(
621                locator.getFileSystem(), DEFAULT_FILE_SYSTEM)
622                : DEFAULT_FILE_SYSTEM;
623    }
624
625    /**
626     * Obtains a non <b>null</b> {@code FileLocationStrategy} object from the
627     * passed in {@code FileLocator}. If the {@code FileLocator} is not
628     * <b>null</b> and has a {@code FileLocationStrategy} defined, this strategy
629     * is returned. Otherwise, result is the default
630     * {@code FileLocationStrategy}.
631     *
632     * @param locator the {@code FileLocator}
633     * @return the {@code FileLocationStrategy} for this {@code FileLocator}
634     */
635    static FileLocationStrategy obtainLocationStrategy(FileLocator locator)
636    {
637        return (locator != null) ? ObjectUtils.defaultIfNull(
638                locator.getLocationStrategy(), DEFAULT_LOCATION_STRATEGY)
639                : DEFAULT_LOCATION_STRATEGY;
640    }
641
642    /**
643     * Creates a fully initialized {@code FileLocator} based on the specified
644     * URL.
645     *
646     * @param src the source {@code FileLocator}
647     * @param url the URL
648     * @return the fully initialized {@code FileLocator}
649     */
650    private static FileLocator createFullyInitializedLocatorFromURL(FileLocator src,
651            URL url)
652    {
653        FileLocator.FileLocatorBuilder fileLocatorBuilder = fileLocator(src);
654        if (src.getSourceURL() == null)
655        {
656            fileLocatorBuilder.sourceURL(url);
657        }
658        if (StringUtils.isBlank(src.getFileName()))
659        {
660            fileLocatorBuilder.fileName(getFileName(url));
661        }
662        if (StringUtils.isBlank(src.getBasePath()))
663        {
664            fileLocatorBuilder.basePath(getBasePath(url));
665        }
666        return fileLocatorBuilder.create();
667    }
668
669    /**
670     * Creates the default location strategy. This method creates a combined
671     * location strategy as described in the comment of the
672     * {@link #DEFAULT_LOCATION_STRATEGY} member field.
673     *
674     * @return the default {@code FileLocationStrategy}
675     */
676    private static FileLocationStrategy initDefaultLocationStrategy()
677    {
678        FileLocationStrategy[] subStrategies =
679                new FileLocationStrategy[] {
680                        new ProvidedURLLocationStrategy(),
681                        new FileSystemLocationStrategy(),
682                        new AbsoluteNameLocationStrategy(),
683                        new BasePathLocationStrategy(),
684                        new HomeDirectoryLocationStrategy(true),
685                        new HomeDirectoryLocationStrategy(false),
686                        new ClasspathLocationStrategy()
687                };
688        return new CombinedLocationStrategy(Arrays.asList(subStrategies));
689    }
690}