se.kth.depclean.util.FileUtils Maven / Gradle / Ivy

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package se.kth.depclean.util;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.file.Files;

public final class FileUtils {

    //--------------------------------/
    //-------- CONSTRUCTOR/S --------/
    //------------------------------/

    private FileUtils() {
    }

    //--------------------------------/
    //------- PUBLIC METHOD/S -------/
    //------------------------------/

    /**
     * Deletes a directory recursively.
     *
     * @param directory The directory to be deleted.
     * @throws IOException In case of IO issues.
     */
    public static void deleteDirectory(final File directory) throws IOException {
        if (!directory.exists()) {
            return;
        }
        if (!isSymlink(directory)) {
            cleanDirectory(directory);
        }
        if (!directory.delete()) {
            final String message = "Unable to delete directory " + directory + '.';
            throw new IOException(message);
        }
    }

    //--------------------------------/
    //------ PRIVATE METHOD/S -------/
    //------------------------------/

    private static boolean isSymlink(final File file) throws IOException {
        if (file == null) {
            throw new NullPointerException("File must be not null");
        }
        return Files.isSymbolicLink(file.toPath());
    }

    private static void cleanDirectory(final File directory) throws IOException {
        final File[] files = verifiedListFiles(directory);
        IOException exception = null;
        for (final File file : files) {
            try {
                forceDelete(file);
            } catch (final IOException ioe) {
                exception = ioe;
            }
        }
        if (null != exception) {
            throw exception;
        }
    }

    private static File[] verifiedListFiles(final File directory) throws IOException {
        if (!directory.exists()) {
            final String message = directory + " does not exist";
            throw new IllegalArgumentException(message);
        }
        if (!directory.isDirectory()) {
            final String message = directory + " is not a directory";
            throw new IllegalArgumentException(message);
        }
        final File[] files = directory.listFiles();
        if (files == null) {  // null if security restricted
            throw new IOException("Failed to list contents of " + directory);
        }
        return files;
    }

    private static void forceDelete(final File file) throws IOException {
        if (file.isDirectory()) {
            deleteDirectory(file);
        } else {
            final boolean filePresent = file.exists();
            if (file.delete()) {
                return;
            }
            if (!filePresent) {
                throw new FileNotFoundException("File does not exist: " + file);
            }
            final String message = "Unable to delete file: " + file;
            throw new IOException(message);
        }
    }
}