java BlobStore和Google SPI AppEngine端点

Question

我正在使用localhost:8080/_ah/api/explorer google explore:我一直在获取

{
 "error": {
  "message": "com.google.appengine.repackaged.org.codehaus.jackson.map.JsonMappingException: Can not construct instance of javax.servlet.http.HttpServletResponse, problem: abstract types can only be instantiated with additional type information\n at [Source: N/A; line: -1, column: -1]",
  "code": 400,
  "errors": [
   {
    "domain": "global",
    "reason": "badRequest",
    "message": "com.google.appengine.repackaged.org.codehaus.jackson.map.JsonMappingException: Can not construct instance of javax.servlet.http.HttpServletResponse, problem: abstract types can only be instantiated with additional type information\n at [Source: N/A; line: -1, column: -1]"
   }
  ]
 }

我的Google SPI代码是：

    @ApiMethod(name = "findBillImage", httpMethod = ApiMethod.HttpMethod.GET )
public void findImage(HttpServletResponse httpServletResponse ,  @Named("blobkey") String blobKeyValue)   throws IOException {
     BlobKey blobKey = new BlobKey( blobKeyValue );
     BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();          
     blobstoreService.serve(blobKey, httpServletResponse);       
}

每当我尝试向HttpServletResponse写入任何内容时，都会收到此错误。我不明白为什么我不能写入httpServletResponse

Answer 1

所以。对我来说，答案实际上是“设计”。

由于我使用谷歌应用引擎实现了"REST“，所以我不应该修改HttpResponse来返回”图像“。

因此，将图像“服务”回HttpResponse并不理想。我应该直接将带有存储URL的映像公开给客户端。

https://storage.cloud.google.com/myapp.appspot.com/20160603_154924.jpg

我不能说我“100%”喜欢这个答案，但从我读到的内容来看，我相信这是正确的。