[IO-250] Add FileUtils.pathTo(File aFile, File fromAnotherFile)

• Type: New Feature
• Status: Resolved
• Priority: Minor
• Resolution: Won't Do
• Fix Version/s: 3.x

Environment

n/a

• Assignee: Unassigned
• Reporter: Jasper Blues
• Created: 30/Sep/10 08:35
• Updated: 03/Feb/24 01:46
• Resolved: 03/Feb/24 01:46

Description

Please consider adding the following method to org.apache.commons.io.FileUtils. I've submitted the method, with test cases below (rather than create a patch file). As a single method, it should prove very simple to integrate.

The method returns the path to a file, from another file, as described in the Javadoc method header below:

    /**
     * Returns the path of a aFile relative to another aFile, for example the location of a file: 
     * <code>resources/language/english/foobar.properties</code> relative to
     * <code>resources/language/japanese/foobar.properties</code> is
     * <code>../../english/foobar.properties</code>
     *
     * @param aFile           the aFile to check relative location
     * @param fromAnotherFile the base location
     * @return the relative location path
     * @throws java.io.IOException on IO error
     */
    public static String pathTo(File aFile, File fromAnotherFile) throws IOException {
        LOGGER.debug("Find path to file: " + aFile.toString() + " from file: " + fromAnotherFile.toString());
        Stack<File> fileToDirectories = directoriesFor(aFile);
        Stack<File> fileFromDirectories = directoriesFor(fromAnotherFile);

        while (fileToDirectories.peek().equals(fileFromDirectories.peek())) {
            fileToDirectories.pop();
            fileFromDirectories.pop();
            if (fileToDirectories.isEmpty() || fileFromDirectories.isEmpty()) {
                break;
            }
        }

        StringBuilder pathToCommonParentDirectory = new StringBuilder();
        while (!fileFromDirectories.isEmpty()) {
            pathToCommonParentDirectory.append("../");
            fileFromDirectories.pop();
        }

        StringBuilder pathToFileFromCommonParentDirectory = new StringBuilder();
        while (!fileToDirectories.isEmpty()) {
            pathToFileFromCommonParentDirectory.append(fileToDirectories.pop().getName());
            if (!fileToDirectories.isEmpty()) {
                pathToFileFromCommonParentDirectory.append("/");
            }
        }
        return pathToCommonParentDirectory.toString() + pathToFileFromCommonParentDirectory.toString();
    }

    private static Stack<File> directoriesFor(File file) throws IOException {
        Stack<File> pathElements = new Stack<File>();
        for (File element = file.getCanonicalFile(); element != null; element = element.getParentFile()) {
            pathElements.push(element);
        }
        return pathElements;
    }

. . . this is useful for batch processing, web applications, etc.

Test Cases:

     @Test
    public void pathTo() throws IOException {
        //Setup
        File file1 = new File("configs/js/en/a.xml");
        File file2 = new File("configs/js/ja/a.xml");
        Assert.assertNotNull(file1);
        Assert.assertNotNull(file2);

        //Test
        Assert.assertEquals("../../en/a.xml", FileUtils.pathTo(file1, file2));
    }

    @Test
    public void pathTo_windowsStyleOnUnixMachine() throws IOException {
        File file1 = new File("c:/fred/foobar/dude.properties");
        File file2 = new File("c:/data/zz.txt");

        Assert.assertEquals("../../fred/foobar/dude.properties", FileUtils.pathTo(file1, file2));
        Assert.assertEquals("../../../data/zz.txt", FileUtils.pathTo(file2, file1));
    }

    @Test
    public void pathTo_fromParentDirectory() throws IOException {
        File file1 = new File("ui-performance-enhancer/out/test/ui-performance-enhancer/configs/css/imported.xml");
        File file2 = new File("ui-performance-enhancer/out/test/ui-performance-enhancer/configs/css");
        Assert.assertEquals("imported.xml", FileUtils.pathTo(file1, file2));

    }