Android Studio无法向电脑D盘写入文件

我利用安卓的单元测试向D盘写入从网上获取的压缩包文件，后缀名是.rar，但是无法写入D盘

@Test
    public void Test() throws IOException {
        Response<ResponseBody> response = wanAndroidService3.download("http://down.crx4.com/down.php?id=L0kvOFdPeS9OQ3Q3WGt0OW92NnFFR2o3QXNyMlhuWTZaSjNsZGE3RVR0SXBDRnA0OGIrdWZsUEl0b2RFeWF0OA==").execute();
        InputStream inputStream = response.body().byteStream();
        FileOutputStream fileOutputStream = new FileOutputStream("D:\\a.rar");
        byte[] bytes = new byte[4096];
        int len = 0; //读到了多长
        while((len = inputStream.read(bytes)) != -1) { //把读到的数据放到bytes里
            fileOutputStream.write(bytes, 0, len);
        }
        fileOutputStream.close();
        inputStream.close();
    }

报错如下

没有权限，换个路径试试