Android:读取所选文件并返回字符串的函数

private String readFileAsString(Uri uri) {
    StringBuilder stringBuilder = new StringBuilder();
    try {
        InputStream inputStream = getContentResolver().openInputStream(uri);
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        String line;
        while ((line = reader.readLine()) != null) {
            stringBuilder.append(line);
        }
        reader.close();
        inputStream.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
    return stringBuilder.toString();
}