trunk/core/src/main/java/org/apache/commons/vfs2/util/FileObjectUtils.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.vfs2.util;

import org.apache.commons.vfs2.FileObject;
import org.apache.commons.vfs2.FileSystemException;
import org.apache.commons.vfs2.impl.DecoratedFileObject;
import org.apache.commons.vfs2.provider.AbstractFileObject;

/**
 * Stuff to get some strange things from an FileObject.
 */
public final class FileObjectUtils
{
    private FileObjectUtils()
    {
    }

    /**
     * Get access to the base object even if decorated.
     * @param fileObject The FileObject.
     * @return The decorated FileObject or null.
     * @throws FileSystemException if an error occurs.
     */
    public static AbstractFileObject getAbstractFileObject(final FileObject fileObject) throws FileSystemException
    {
        Object searchObject = fileObject;
        while (searchObject instanceof DecoratedFileObject)
        {
            searchObject = ((DecoratedFileObject) searchObject).getDecoratedFileObject();
        }
        if (searchObject instanceof AbstractFileObject)
        {
            return (AbstractFileObject) searchObject;
        }
        if (searchObject == null)
        {
            return null;
        }

        throw new FileSystemException("vfs.util/find-abstract-file-object.error",
                fileObject == null ? "null" : fileObject.getClass().getName());
    }

    /**
     * Check if the given FileObject is instance of given class argument.
     * @param fileObject The FileObject.
     * @param wantedClass The Class to check.
     * @return true if fileObject is an instance of the specified Class.
     * @throws FileSystemException if an error occurs.
     */
    public static boolean isInstanceOf(final FileObject fileObject, final Class<?> wantedClass)
        throws FileSystemException
    {
        Object searchObject = fileObject;
        while (searchObject instanceof DecoratedFileObject)
        {
            if (wantedClass.isInstance(searchObject))
            {
                return true;
            }

            searchObject = ((DecoratedFileObject) searchObject).getDecoratedFileObject();
        }

        if (wantedClass.isInstance(searchObject))
        {
            return true;
        }

        return false;
    }
}