Google App Engine和Cloud Storage API

Question

我尝试通过 GAE 应用从 Google云端存储获取文件。

我用params（一个简单的HTML表单）得到了桶和文件名，我称之为Servlet：

String bucket = req.getParameter("bucket");
String filename = req.getParameter("filename");

BlobstoreService blobstoreService = BlobstoreServiceFactory
        .getBlobstoreService();
BlobKey blobKey = blobstoreService.createGsBlobKey("/gs/" + bucket
        + "/" + filename);
blobstoreService.serve(blobKey, resp);

我在 localhost 和 GAE 上收到此错误：

The API package 'blobstore' or call 'CreateEncodedGoogleStorageKey()' was not found.