FileUtils.java Source code

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Here is the source code for FileUtils.java

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/* 
 * 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.
 *
 */

import java.io.File;

/**
 * 
 * FileUtils is a collection of routines for common file system operations.
 * 
 * @author Dan Jemiolo (danj)
 * 
 */

public final class FileUtils {

    /**
     * 
     * Merges the two paths to create a valid version of the second path. This
     * method should be used when you encounter a relative path in a document and
     * must resolve it based on the path of the current document. An example would
     * be: <br>
     * <br>
     * <b>original path</b> - files/customers/Orders.xml <br>
     * <br>
     * <b>relative path</b> - ../Accounts.xml <br>
     * <br>
     * <b>result</b> - files/customers/Accounts.xml <br>
     * <br>
     * The only time this method cannot be used is if the original path is for a
     * file that is in the root (has no directory as part of its path) and the
     * relative path starts with "..".
     * 
     * @param originalPath
     *          The path of the file that references another file.
     * 
     * @param relativePath
     *          The path of the other file, which is relative to the original.
     * 
     * @return A proper path for the other file, one that can be used to open and
     *         verify the file.
     * 
     */
    public static String createRelativePath(String originalPath, String relativePath) {
        if (originalPath == null)
            throw new NullPointerException("NullOriginalPath");

        if (relativePath == null)
            throw new NullPointerException("NullRelativePath");

        //
        // remove ./ if present
        //
        if (relativePath.startsWith("./"))
            relativePath = relativePath.substring(2);

        //
        // remove any .. reference by taking off the last section/ of
        // the original path
        //
        if (relativePath.startsWith("../")) {
            int slash = originalPath.lastIndexOf('/');
            originalPath = originalPath.substring(0, slash);
            relativePath = relativePath.substring(3);
        }

        int slash = originalPath.lastIndexOf('/');

        if (slash < 0)
            return relativePath;

        String dir = originalPath.substring(0, slash + 1);
        return dir + relativePath;
    }

}