android.os.ParcelFileDescriptor#parseMode ( )源码实例Demo

/**
 * Convenience for subclasses that wish to implement {@link #openFile}
 * by looking up a column named "_data" at the given URI.
 *
 * @param uri The URI to be opened.
 * @param mode The file mode.  May be "r" for read-only access,
 * "w" for write-only access (erasing whatever data is currently in
 * the file), "wa" for write-only access to append to any existing data,
 * "rw" for read and write access on any existing data, and "rwt" for read
 * and write access that truncates any existing file.
 *
 * @return Returns a new ParcelFileDescriptor that can be used by the
 * client to access the file.
 */
protected final @NonNull ParcelFileDescriptor openFileHelper(@NonNull Uri uri,
        @NonNull String mode) throws FileNotFoundException {
    Cursor c = query(uri, new String[]{"_data"}, null, null, null);
    int count = (c != null) ? c.getCount() : 0;
    if (count != 1) {
        // If there is not exactly one result, throw an appropriate
        // exception.
        if (c != null) {
            c.close();
        }
        if (count == 0) {
            throw new FileNotFoundException("No entry for " + uri);
        }
        throw new FileNotFoundException("Multiple items at " + uri);
    }

    c.moveToFirst();
    int i = c.getColumnIndex("_data");
    String path = (i >= 0 ? c.getString(i) : null);
    c.close();
    if (path == null) {
        throw new FileNotFoundException("Column _data not found.");
    }

    int modeBits = ParcelFileDescriptor.parseMode(mode);
    return ParcelFileDescriptor.open(new File(path), modeBits);
}
 

/**
 * Convenience for subclasses that wish to implement {@link #openFile}
 * by looking up a column named "_data" at the given URI.
 *
 * @param uri The URI to be opened.
 * @param mode The file mode.  May be "r" for read-only access,
 * "w" for write-only access (erasing whatever data is currently in
 * the file), "wa" for write-only access to append to any existing data,
 * "rw" for read and write access on any existing data, and "rwt" for read
 * and write access that truncates any existing file.
 *
 * @return Returns a new ParcelFileDescriptor that can be used by the
 * client to access the file.
 */
protected final @NonNull ParcelFileDescriptor openFileHelper(@NonNull Uri uri,
        @NonNull String mode) throws FileNotFoundException {
    Cursor c = query(uri, new String[]{"_data"}, null, null, null);
    int count = (c != null) ? c.getCount() : 0;
    if (count != 1) {
        // If there is not exactly one result, throw an appropriate
        // exception.
        if (c != null) {
            c.close();
        }
        if (count == 0) {
            throw new FileNotFoundException("No entry for " + uri);
        }
        throw new FileNotFoundException("Multiple items at " + uri);
    }

    c.moveToFirst();
    int i = c.getColumnIndex("_data");
    String path = (i >= 0 ? c.getString(i) : null);
    c.close();
    if (path == null) {
        throw new FileNotFoundException("Column _data not found.");
    }

    int modeBits = ParcelFileDescriptor.parseMode(mode);
    return ParcelFileDescriptor.open(new File(path), modeBits);
}
 

private static int parseMode(String mode) {
  if (VERSION.SDK_INT >= VERSION_CODES.KITKAT) {
    return ParcelFileDescriptor.parseMode(mode);
  } else {
    final int modeBits;
    if ("r".equals(mode)) {
      modeBits = ParcelFileDescriptor.MODE_READ_ONLY;
    } else if ("w".equals(mode) || "wt".equals(mode)) {
      modeBits = ParcelFileDescriptor.MODE_WRITE_ONLY
          | ParcelFileDescriptor.MODE_CREATE
          | ParcelFileDescriptor.MODE_TRUNCATE;
    } else if ("wa".equals(mode)) {
      modeBits = ParcelFileDescriptor.MODE_WRITE_ONLY
          | ParcelFileDescriptor.MODE_CREATE
          | ParcelFileDescriptor.MODE_APPEND;
    } else if ("rw".equals(mode)) {
      modeBits = ParcelFileDescriptor.MODE_READ_WRITE
          | ParcelFileDescriptor.MODE_CREATE;
    } else if ("rwt".equals(mode)) {
      modeBits = ParcelFileDescriptor.MODE_READ_WRITE
          | ParcelFileDescriptor.MODE_CREATE
          | ParcelFileDescriptor.MODE_TRUNCATE;
    } else {
      throw new IllegalArgumentException("Bad mode '" + mode + "'");
    }
    return modeBits;
  }
}