使用Android购买状态API：未找到

Question

我有一个Android应用程序，它正在使用“Google Play In-app Billing”库来购买应用程序。

我读过最好使用Purchase Status API（Google Play Android Developer API v1.1）验证后端服务器中的购买情况。

我找到了一个关于如何获取刷新令牌，如何使用它来获取访问令牌以及如何使用API​​的示例。

HttpHost proxy = new HttpHost("10.12.54.8", 8080, "http");

HttpClient client = new DefaultHttpClient();
client.getParams().setParameter(ConnRoutePNames.DEFAULT_PROXY, proxy);
ApacheHttpTransport HTTP_TRANSPORT = new ApacheHttpTransport(client);

JsonFactory JSON_FACTORY = new JacksonFactory();   

TokenResponse tokenResponse = new TokenResponse();        
tokenResponse.setAccessToken(accessToken);
tokenResponse.setRefreshToken(refreshToken);
tokenResponse.setExpiresInSeconds(3600L);
tokenResponse.setScope("https://www.googleapis.com/auth/androidpublisher/v1.1/applications");
tokenResponse.setTokenType("Bearer");

HttpRequestInitializer credential = new GoogleCredential.Builder().setTransport(HTTP_TRANSPORT).setJsonFactory(JSON_FACTORY)
                .setClientSecrets(GOOGLE_CLIENT_ID, GOOGLE_CLIENT_SECRET).build().setFromTokenResponse(tokenResponse);

AndroidPublisher publisher = new AndroidPublisher.Builder(HTTP_TRANSPORT, JSON_FACTORY, credential).setApplicationName(GOOGLE_PRODUCT_NAME).build(); 

AndroidPublisher.Inapppurchases purchases = publisher.inapppurchases();
Get get = purchases.get(GOOGLE_PACKAGE_NAME, ITEM_ID, purchaseToken);
InappPurchase purch = get.execute();

但是我收到了404 Not Found。为什么呢？

提前致谢。