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.vfs2;
018
019import java.lang.reflect.InvocationTargetException;
020import java.lang.reflect.Method;
021
022/**
023 * The main entry point for the VFS. Used to create {@link FileSystemManager} instances.
024 */
025public final class VFS {
026    /** The URI style */
027    private static Boolean uriStyle;
028
029    /** The FileSystemManager */
030    private static FileSystemManager instance;
031
032    private VFS() {
033    }
034
035    /**
036     * Returns the default {@link FileSystemManager} instance.
037     * <p>
038     * Warning, if you close this instance you may affect all current and future users of this manager singleton.
039     *
040     * @return The FileSystemManager.
041     * @throws FileSystemException if an error occurs creating the manager.
042     */
043    public static synchronized FileSystemManager getManager() throws FileSystemException {
044        if (instance == null) {
045            instance = createManager("org.apache.commons.vfs2.impl.StandardFileSystemManager");
046        }
047        return instance;
048    }
049
050    /**
051     * Creates a file system manager instance.
052     *
053     * @param managerClassName The specific manager impelmentation class name.
054     * @return The FileSystemManager.
055     * @throws FileSystemException if an error occurs creating the manager.
056     */
057    private static FileSystemManager createManager(final String managerClassName) throws FileSystemException {
058        try {
059            // Create instance
060            final Class<?> mgrClass = Class.forName(managerClassName);
061            final FileSystemManager mgr = (FileSystemManager) mgrClass.newInstance();
062
063            try {
064                // Initialize
065                final Method initMethod = mgrClass.getMethod("init", (Class[]) null);
066                initMethod.invoke(mgr, (Object[]) null);
067            } catch (final NoSuchMethodException ignored) {
068                /* Ignore; don't initialize. */
069            }
070
071            return mgr;
072        } catch (final InvocationTargetException e) {
073            throw new FileSystemException("vfs/create-manager.error", managerClassName, e.getTargetException());
074        } catch (final Exception e) {
075            throw new FileSystemException("vfs/create-manager.error", managerClassName, e);
076        }
077    }
078
079    public static boolean isUriStyle() {
080        if (uriStyle == null) {
081            uriStyle = Boolean.FALSE;
082        }
083        return uriStyle.booleanValue();
084    }
085
086    public static void setUriStyle(final boolean uriStyle) {
087        if (VFS.uriStyle != null && VFS.uriStyle.booleanValue() != uriStyle) {
088            throw new IllegalStateException("VFS.uriStyle was already set differently.");
089        }
090        VFS.uriStyle = Boolean.valueOf(uriStyle);
091    }
092
093    /**
094     * Sets the file system manager
095     *
096     * @param manager the file system manager
097     * @since 2.2
098     */
099    public static void setManager(final FileSystemManager manager) {
100        VFS.instance = manager;
101    }
102}