private void queryFiles(){

        String[] projection = new String[] { MediaStore.Files.FileColumns._ID,

            MediaStore.Files.FileColumns.DATA,

            MediaStore.Files.FileColumns.SIZE

        };

        Cursor cursor = getContentResolver().query(

            Uri.parse("content://media/external/file"),

            projection,

            MediaStore.Files.FileColumns.DATA + " like ?",

            new String[]{"%.txt"},

            null);

        if (cursor != null) {

            if (cursor.moveToFirst()) {

                int idindex = cursor

                    .getColumnIndex(MediaStore.Files.FileColumns._ID);

                int dataindex = cursor

                    .getColumnIndex(MediaStore.Files.FileColumns.DATA);

                int sizeindex = cursor

                    .getColumnIndex(MediaStore.Files.FileColumns.SIZE);

                do {

                    String id = cursor.getString(idindex);

                    String path = cursor.getString(dataindex);

                    String size = cursor.getString(sizeindex);

                    docBean.setId(id);

                    docBean.setPath(path);

                    docBean.setSize(size);

                    int dot=path.lastIndexOf("/");

                    String name=path.substring(dot+1);

                    Log.e("test",name);

                } while (cursor.moveToNext());

            }

        }

        cursor.close();

    }