android 获取u盘下所有图片路径存入List

public List<String> mList = new ArrayList<String>();
Uri mImageUri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
ContentResolver mContentResolver = getContext()
        .getContentResolver();
Cursor mCursor = mContentResolver.query(mImageUri, null,
        MediaStore.Images.Media.MIME_TYPE + "=? or "
                + MediaStore.Images.Media.MIME_TYPE + "=? or "
                + MediaStore.Images.Media.MIME_TYPE + "=? or "
                + MediaStore.Images.Media.MIME_TYPE + "=?",
        new String[]{"image/jpeg", "image/png", "image/gif", "image/x-ms-bmp"},
        MediaStore.Images.Media.DATE_MODIFIED);
if (mCursor == null) {
    return;
}
mCursor.moveToLast();
while (mCursor.moveToPrevious()) {
    String path = mCursor.getString(mCursor
            .getColumnIndex(MediaStore.Images.Media.DATA));
    if (!mList.contains(path))
        mList.add(path);
}
mCursor.close();