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所以我正在使用 Google App Engine 作为应用程序，我需要将图片从 GAE 传递到 android 客户端。为了做到这一点，我虽然将图片转换为字符串并将其作为 json 发送......（我发现这是一个不错的想法：使用 Python Base64 压缩 GAE Blob 图像？）。

问题是我很难在 Base64 中进行转换。我已经尝试过这种方法（在 AppEngine 上对上传的二进制数据进行 Base64 编码），但它对我不起作用，因为我收到错误：

 File "/base/data/home/apps/s~testehan/1.366670408737847123/main.py", line 462, in post
    img = Imagine( name=fileupload.filename, data=fileupload.file.read() )
  File "/python27_runtime/python27_lib/versions/1/google/appengine/ext/db/__init__.py", line 970, in __init__
    prop.__set__(self, value)
  File "/python27_runtime/python27_lib/versions/1/google/appengine/ext/db/__init__.py", line 614, in __set__
    value = self.validate(value)
  File "/python27_runtime/python27_lib/versions/1/google/appengine/ext/db/__init__.py", line 2806, in validate
    value = super(UnindexedProperty, self).validate(value)
  File "/python27_runtime/python27_lib/versions/1/google/appengine/ext/db/__init__.py", line 641, in validate
    raise BadValueError('Property %s is required' % self.name)
BadValueError: Property data is required

原因是当我在日志中显示 upload_file.file.read() 时，我得到了这个：

Content-Type: image/jpeg
Content-Length: 36187
X-AppEngine-Upload-Creation: 2013-04-14 08:35:46.123191
Content-MD5: MDYzNWE2Y2FkMzFlMGVhNzgwNmEwNzhiOGNkZTdhNTI=
Content-Disposition: form-data; name=img; filename="blabla.jpg"

所以我的问题是..我如何阅读这张图片并将其存储为文本属性，以便我能够传递它？

谢谢

编辑：后处理程序

   class Imagine(db.Model):
    name = db.StringProperty(required=True)
    data = db.TextProperty(required=True)
    created = db.DateTimeProperty(auto_now_add=True)

class PostImage(UserHandler):  
    def post(self, restaurant, category):
        logging.info("ImagestoreHandler#post %s", self.request.path)
        name= self.request.get('name')
        description= self.request.get('description')
        sizes = int(self.request.get('sizes'))

        fileupload = self.request.POST.get("img",None)
        if fileupload is None : return self.error(400)

        content_type = fileupload.type or getContentType( fileupload.filename )
        if content_type is None: 
            self.error(400)
            self.response.headers['Content-Type'] = 'text/plain'
            self.response.out.write( "Unsupported image type: " + fileupload.filename )
            return
        logging.debug( "File upload: %s, mime type: %s", fileupload.filename, content_type )

        try:
            logging.info('citesc fisierul : ' + fileupload.file.read())
            img = Imagine( name=fileupload.filename, data=fileupload.file.read() )
            img.put()
            (img_name, img_url) = self._store_image( fileupload.filename, fileupload.file, content_type )
            self.response.headers['Location'] = img_url
            ex=None
        except Exception, err:
            logging.exception( "Error while storing image" )
            self.error(400)
            self.response.headers['Content-Type'] = 'text/plain'
            self.response.out.write("Error uploading image: " + str(err))
            return
    #self.redirect(urlBase % img.key() )  #dummy redirect is acceptable for non-AJAX clients,
    # location header should be acceptable for true REST clients, however AJAX requests 
    # might not be able to access the location header so we'll write a 200 response with 
    # the new URL in the response body:

        acceptType = self.request.accept.best_match( listRenderers.keys() )
        out = self.response.out
        if acceptType == 'application/json':
            self.response.headers['Content-Type'] = 'application/json'
            out.write( '{"name":"%s","href":"%s"}' % ( img_name, img_url ) )
        elif re.search( 'html|xml', acceptType ):
            self.response.headers['Content-Type'] = 'text/html'
            out.write( '<a href="%s">%s</a>' % ( img_url, img_name) )

    def _store_image(self, name, file, content_type):
        """POST handler delegates to this method for actual image storage; as
        a result, alternate implementation may easily override the storage
        mechanism without rewriting the same content-type handling. 

        This method returns a tuple of file name and image URL."""

        img_enc = base64.b64encode(file.read())
        img_enc_struct = "data:%s;base64,%s" % (content_type, img_enc)
        logging.info('file name is '+name)
        logging.info('file is '+file.read())
        img = Imagine( name=name, data=file.read() )
        img.put()
        return ( str(img.name), img.key() )

形式 ：

<form action="{{ upload_url }}" method="POST" enctype="multipart/form-data">
    <input name="name" placeholder="Product name" type="text" /> 
        <input type="file" name="img"/>
             <br />
    <input type="submit" value="Submit product!" />
</form>
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