Google App Engine-使用模拟的POST通过字节数组更新blobstore

WARNING: /_ah/login
java.lang.NullPointerException
  at com.google.appengine.api.users.dev.LoginCookieUtils.encodeEmailAsUserId(LoginCookieUtils.java:89)
  at com.google.appengine.api.users.dev.LoginCookieUtils.createCookie(LoginCookieUtils.java:41)
  at com.google.appengine.api.users.dev.LocalLoginServlet.doPost(LocalLoginServlet.java:90)

byte[] htmlData = // ...I already have the byte array I want to store/update)

    BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();
            String uploadURL = blobstoreService.createUploadUrl(\"/upload\");

                         //add host if in dev mode
             if(uploadURL.indexOf(\"http\") == -1)
             {
                 uploadURL = \"http://localhost:8888\" + uploadURL;
             }
             URL url = new URL(uploadURL);
             // create a boundary string
             String boundary = MultiPartFormOutputStream.createBoundary();
             URLConnection urlConn = MultiPartFormOutputStream.createConnection(url);
             urlConn.setReadTimeout(15000);
             urlConn.setRequestProperty(\"Accept\", \"*/*\");
             urlConn.setRequestProperty(\"Content-Type\", MultiPartFormOutputStream.getContentType(boundary));
             // set some other request headers...
             urlConn.setRequestProperty(\"Connection\", \"Keep-Alive\");
             urlConn.setRequestProperty(\"Cache-Control\", \"no-cache\");
             // no need to connect because getOutputStream() does it
             MultiPartFormOutputStream out = new MultiPartFormOutputStream(urlConn.getOutputStream(), boundary);
out.writeField(\"param\", \"value\")
out.writeFile(\"myFile\", \"multipart/form-data\", \"content.html\", htmlData);
         out.close();

public class Upload extends HttpServlet 
{

    private BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();

    public void doPost(HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException 
    {
        UserService userService = UserServiceFactory.getUserService();
        User user = userService.getCurrentUser();
        Map<String, BlobKey> blobs = blobstoreService.getUploadedBlobs(req);
        BlobKey blobKey = blobs.get(\"myFile\");
        String value = req.getParameter(\"param\");
        Topic t = pm.getObjectById(Topic.class, key);
        t.setParam(\"value\");
    try
    {
        pm.makePersistent(t);
    }