Android Open Source - base-android-utils File Utils

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License

The source code is released under:

Apache License

Java Source Code

package me.pc.mobile.helper.v14.files;
//w  ww . j a  va 2s.c  o m
import android.content.Context;
import android.util.Log;

import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;

/** Common File IO Utils */
public class FileUtils {

  private FileUtils() {}

  private static String TAG = FileUtils.class.getSimpleName();
  private static boolean WARN = false;

  // =========================================================================
  // Android IO methods wrappers
  // =========================================================================
  /**
   * Given a string which corresponds to a directory path relative to the root
   * of *internal* storage creates this directory path if it does not exists.
   * Returns this path or throws IOException on failure
   *
   * @param directoryName
   *            the path to the desired directory *relative* to the root of
   *            *internal* storage
   * @return the File that corresponds to the path if it was created
   *         successfully or the path already existed and is a directory
   * @throws IOException
   *             if the directory can't be created
   */
  public static File createDirInternal(Context ctx,
      String directoryName) throws IOException {
    File directory = new File(ctx.getFilesDir(), directoryName);
    if (createDir(directory)) return directory;
    throw new IOException("Cannot create directory " + directoryName
      + " in internal storage");
  }

  // =========================================================================
  // IO FileUtils
  // =========================================================================
  /**
   * Returns true if the directory exists and is empty *OR* if it does not
   * exist. Will also return true if the directory is security restricted.
   * Will throw IllegalArgumentException if the directory is not a directory.
   *
   * @param directory
   *            must be a directory
   * @return true if the directory does not exist or is empty or not
   *         accessible, false otherwise
   * @throws NullPointerException
   *             if the directory is <code>null</code>
   * @throws IllegalArgumentException
   *             if the directory is not a directory
   */
  public static boolean isEmptyOrAbsent(File directory) {
    if (!directory.exists()) {
      return true;
    }
    return sizeOfDirectory(directory) == 0;
  }

  /**
   * List the files in the directory. Wrapper around {@link File#listFiles()}.
   *
   * @param directory
   *            directory to inspect, must not be <code>null</code>
   * @return a List<File> of the files contained in the directory
   * @throws NullPointerException
   *             if the directory is <code>null</code>
   * @throws IllegalArgumentException
   *             if the directory does not exist or is not a directory
   */
  public static List<File> listFiles(File directory) {
    File[] listFiles = directory.listFiles();
    if (listFiles == null) {
      String message = directory
        + ((directory.exists()) ? " is not a directory"
            : " does not exist");
      throw new IllegalArgumentException(message);
    }
    return Arrays.asList(listFiles); // empty array => empty List
  }

  // =========================================================================
  // Package helpers
  // =========================================================================
  /**
   * Given a File which corresponds to a _directory_ path creates this path if
   * it does not exists.
   *
   * @param directory
   *            the File instance whose path must be created
   * @return true if the path already exists and is a directory or was created
   *         successfully as a directory, false otherwise
   */
  static boolean createDir(File directory) {
    return directory.isDirectory() || directory.mkdirs();
  }

  // =========================================================================
  // Helpers
  // =========================================================================
  /**
   * Counts the size of a directory recursively (sum of the length of all
   * files). Modifies Apache commons <a href=
   * "http://commons.apache.org/proper/commons-io/javadocs/api-release/org/apache/commons/io/FileUtils.html#sizeOfDirectory%28java.io.File%29"
   * >FileUtils#sizeOfDirectory(java.io.File)</a> TODO : <a
   * href="http://stackoverflow.com/a/3169970/281545">circular paths</a>
   *
   * @param directory
   *            directory to inspect, must not be <code>null</code>
   * @return size of directory in bytes, 0 if directory is security restricted
   * @throws NullPointerException
   *             if the directory is <code>null</code>
   * @throws IllegalArgumentException
   *             if the directory does not exist or is not a directory
   */
  private static long sizeOfDirectory(File directory) {
    File[] files = directory.listFiles();
    if (files == null) { // null maybe if security restricted
      String message = null;
      if (!directory.exists()) {
        message = directory + " does not exist";
      } else if (!directory.isDirectory()) {
        message = directory + " is not a directory";
      }
      if (message != null) {
        throw new IllegalArgumentException(message);
      }
      return 0L;
    }
    long size = 0;
    for (int i = 0; i < files.length; ++i) {
      File file = files[i];
      if (file.isDirectory()) size += sizeOfDirectory(file);
      else size += file.length();
    }
    return size;
  }

  private static void w(String string, Throwable t) {
    if (WARN) {
      Log.w(TAG, string, t);
    }
  }
}

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