如何在android studio中获取Facebook封面照片

Question

我正在开发一个应用程序，我已经使用我的Facebook帐户登录了。我在从facebook个人资料中获取封面照片并在ImageView中设置时遇到问题。我尝试按照本指南进行操作：https://developers.facebook.com/docs/graph-api/reference/v2.7/cover-photo/#Overview但是每次运行应用程序时都会崩溃。有谁知道我做错了什么？

/* make the API call */
       new GraphRequest(
               AccessToken.getCurrentAccessToken(),
               "...?fields={fieldname_of_type_CoverPhoto}",
               null,
               HttpMethod.GET,
               new GraphRequest.Callback() {
                   public void onCompleted(GraphResponse response) {
                       URL cover = response.getConnection().getURL();
                       try {
                           Bitmap coverPicture = BitmapFactory.decodeStream(cover.openConnection().getInputStream());
                           Toast.makeText(ProfilActivity.this, "bitmap" + coverPicture, Toast.LENGTH_SHORT).show();
                           ImageView coverS = (ImageView) findViewById(R.id.cover);
                           coverS.setImageBitmap(coverPicture);

                       } catch (IOException e) {
                           e.printStackTrace();
                       }
                       Toast.makeText(ProfilActivity.this, "URL" + cover, Toast.LENGTH_SHORT).show();
                   }
               }
       ).executeAsync();