ch.unibas.fittingwizard.infrastructure.base.ResourceUtils.java Source code

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Here is the source code for ch.unibas.fittingwizard.infrastructure.base.ResourceUtils.java

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/*
 * Copyright (c) 2015, Florent Hedin, Markus Meuwly, and the University of Basel
 * All rights reserved.
 *
 * The 3-clause BSD license is applied to this software.
 * see LICENSE.txt
 *
 */
package ch.unibas.fittingwizard.infrastructure.base;

import java.io.File;
import java.util.regex.Pattern;
import org.apache.commons.io.FilenameUtils;
import org.apache.log4j.Logger;

/**
 * Take from http://stackoverflow.com/questions/204784/how-to-construct-a-relative-path-in-java-from-two-absolute-paths-or-urls
 * User: mhelmer
 * Date: 12.12.13
 * Time: 12:30
 */
public class ResourceUtils {

    private final static Logger logger = Logger.getLogger(ResourceUtils.class);

    public static String getRelativePath(File targetPath, File basePath) {
        return getRelativePath(targetPath.getAbsolutePath(), basePath.getAbsolutePath(), File.separator);
    }

    public static String getRelativePath(String targetPath, String basePath) {
        logger.info(targetPath + "\tand\t" + basePath);
        return getRelativePath(targetPath, basePath, File.separator);
    }

    /**
     * Get the relative path from one file to another, specifying the directory separator.
     * If one of the provided resources does not exist, it is assumed to be a file unless it ends with '/' or
     * '\'.
     *
     * @param targetPath targetPath is calculated to this file
     * @param basePath basePath is calculated from this file
     * @param pathSeparator directory separator. The platform default is not assumed so that we can test Unix behaviour when running on Windows (for example)
     * @return
     */
    public static String getRelativePath(String targetPath, String basePath, String pathSeparator) {

        // Normalize the paths
        String normalizedTargetPath = FilenameUtils.normalizeNoEndSeparator(targetPath);
        String normalizedBasePath = FilenameUtils.normalizeNoEndSeparator(basePath);

        // Undo the changes to the separators made by normalization
        if (pathSeparator.equals("/")) {
            normalizedTargetPath = FilenameUtils.separatorsToUnix(normalizedTargetPath);
            normalizedBasePath = FilenameUtils.separatorsToUnix(normalizedBasePath);

        } else if (pathSeparator.equals("\\")) {
            normalizedTargetPath = FilenameUtils.separatorsToWindows(normalizedTargetPath);
            normalizedBasePath = FilenameUtils.separatorsToWindows(normalizedBasePath);

        } else {
            throw new IllegalArgumentException("Unrecognised dir separator '" + pathSeparator + "'");
        }

        String[] base = normalizedBasePath.split(Pattern.quote(pathSeparator));
        String[] target = normalizedTargetPath.split(Pattern.quote(pathSeparator));

        // First get all the common elements. Store them as a string,
        // and also count how many of them there are.
        StringBuffer common = new StringBuffer();

        int commonIndex = 0;
        while (commonIndex < target.length && commonIndex < base.length
                && target[commonIndex].equals(base[commonIndex])) {
            common.append(target[commonIndex] + pathSeparator);
            commonIndex++;
        }

        if (commonIndex == 0) {
            // No single common path element. This most
            // likely indicates differing drive letters, like C: and D:.
            // These paths cannot be relativized.
            throw new PathResolutionException("No common path element found for '" + normalizedTargetPath
                    + "' and '" + normalizedBasePath + "'");
        }

        // The number of directories we have to backtrack depends on whether the base is a file or a dir
        // For example, the relative path from
        //
        // /foo/bar/baz/gg/ff to /foo/bar/baz
        //
        // ".." if ff is a file
        // "../.." if ff is a directory
        //
        // The following is a heuristic to figure out if the base refers to a file or dir. It's not perfect, because
        // the resource referred to by this path may not actually exist, but it's the best I can do
        boolean baseIsFile = true;

        File baseResource = new File(normalizedBasePath);

        if (baseResource.exists()) {
            baseIsFile = baseResource.isFile();

        } else if (basePath.endsWith(pathSeparator)) {
            baseIsFile = false;
        }

        StringBuffer relative = new StringBuffer();

        if (base.length != commonIndex) {
            int numDirsUp = baseIsFile ? base.length - commonIndex - 1 : base.length - commonIndex;

            for (int i = 0; i < numDirsUp; i++) {
                relative.append(".." + pathSeparator);
            }
        }
        relative.append(normalizedTargetPath.substring(common.length()));
        return relative.toString();
    }

    static class PathResolutionException extends RuntimeException {
        PathResolutionException(String msg) {
            super(msg);
        }
    }
}