java GoogleTokenResponse未执行。。！

Question

我正在尝试制作一个应用程序，该应用程序应该可以在没有安装播放服务的设备上运行。目前我正在使用webview登录。我已在此处成功收到授权码，&；为了检索访问令牌，我使用以下代码段（来自https://developers.google.com/api-client-library/java/google-api-java-client/reference/1.20.0/com/google/api/client/googleapis/auth/oauth2/GoogleAuthorizationCodeTokenRequest）

不知何故，在GoogleTokenResponse上，应用程序在.execute()崩溃。。。我应该在这里改变什么

@Override
            public void onPageFinished(安卓.webkit.WebView view, String url) {
                super.onPageFinished(view, url);
                if (url.startsWith(OAuth2Client.REDIRECT_URI)) {
                    try {
                        if (url.indexOf("code=") != -1) {
                            String code = extractCodeFromUrl(url);

                            try {
                                GoogleTokenResponse response =
                                        new GoogleAuthorizationCodeTokenRequest(new NetHttpTransport(), new JacksonFactory(),
                                                OAuth2Client.CLIENT_ID, OAuth2Client.CLIENT_SECRET,
                                                code, OAuth2Client.REDIRECT_URI)
                                                .execute();                                                                  //debugging stops here!!
                                System.out.println("Access token: " + response.getAccessToken());
                            } catch (TokenResponseException e) {
                                if (e.getDetails() != null) {
                                    System.err.println("Error: " + e.getDetails().getError());
                                    if (e.getDetails().getErrorDescription() != null) {
                                        System.err.println(e.getDetails().getErrorDescription());
                                    }
                                    if (e.getDetails().getErrorUri() != null) {
                                        System.err.println(e.getDetails().getErrorUri());
                                    }
                                } else {
                                    System.err.println(e.getMessage());
                                }
                            }


                        } else if (url.indexOf("error=") != -1) {
                            OAuth2Client.ClearAccessToken(getApplicationContext());
                        }
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                System.out.println("onPageFinished : " + url);
            }