使用Google App Engine将文件上传到Blobstore时出现HTTP 400错误

Question

我正在尝试使用Google App Engine Blobstore上传文件。

它应该是这样工作的：您调用BlobstoreService以获得一个上传URL，并提供一个回调URL。 客户端将重定向到上载URL，发送数据，然后在完成后将使用两个代表blobstore密钥的参数将其重定向到回调URL。

我们将看到，开发服务器的行为与生产服务器不同。

针对生产，我的代码可以完成上传，然后得到一个400错误响应（暗示我的请求有问题），而不是重定向回我的回调URL。 我该如何在生产中调试呢？ 我不知道如何打开Blobstore的日志记录。

因此，我尝试在开发服务器上本地运行它。 这次，如果我未设置'content-length'属性，则会得到411（未设置内容长度）。 但是，如果尝试设置该属性，则会收到“ IllegalStateException：已连接”。 这些例外都不会针对生产发生。

所以我不知道下一步要去哪里。 我需要让它与开发人员合作，以希望可以在本地调试blobstore，或者弄清楚为什么它不能在生产环境中在blobstore上运行。

    public void upload(String uri, File file) throws IOException    {
    HttpURLConnection conn=null;
    HttpURLConnection conn2=null;
    FileInputStream fileInputStream = null;
    DataOutputStream dos=null;
    try {
        String lineEnd = "\r\n";
        String twoHyphens = "--";
        String boundary = "*****";
        int bytesRead, bytesAvailable, bufferSize;
        byte[] buffer;
        int maxBufferSize = 1 * 1024 * 1024; 
        // open a URL connection to the Servlet
        fileInputStream = new FileInputStream(file);
        URL url = new URL(uri);

        // Open a HTTP  connection to  the URL
        conn = (HttpURLConnection) url.openConnection();
        conn.setDoInput(true); // Allow Inputs
        conn.setDoOutput(true); // Allow Outputs
        conn.setUseCaches(false); // Don't use a Cached Copy
        conn.setInstanceFollowRedirects(false);
        conn.setRequestMethod("POST");
        conn.setRequestProperty("Connection", "Keep-Alive");
        conn.setRequestProperty("ENCTYPE", "multipart/form-data");
        conn.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
//          conn.setChunkedStreamingMode(1024);
        conn.setRequestProperty("content-length", String.valueOf(file.length()));   //caused IllegalStateException "Already connected" locally, but not remotely

        log("Orignal URL: " + conn.getURL());
        //conn.connect();   //TODO duplicates url.openConnection() above?
        conn.getInputStream();  //so we can follow the redirect
        String redirectedUrl = conn.getHeaderField("Location");
        log("Redirected URL: " + redirectedUrl);
        //this is horrible and messy but let's get it working then clean it up later

        conn.disconnect();
        url = new URL(redirectedUrl);

        // Open a new HTTP  connection to  the URL
        conn2 = (HttpURLConnection) url.openConnection();
        conn2.setDoInput(true); // Allow Inputs
        conn2.setDoOutput(true); // Allow Outputs
        conn2.setUseCaches(false); // Don't use a Cached Copy
        conn2.setInstanceFollowRedirects(false);
        conn2.setRequestMethod("POST");
        conn2.setRequestProperty("Connection", "Keep-Alive");
        conn2.setRequestProperty("ENCTYPE", "multipart/form-data");
        conn2.setRequestProperty("Content-Type", "multipart/form-data;boundary=" + boundary);
        conn2.setChunkedStreamingMode(maxBufferSize);
        conn2.setRequestProperty("Content-Length", String.valueOf(file.length()));
        conn2.connect();
        dos = new DataOutputStream(conn2.getOutputStream());

        dos.writeBytes(twoHyphens + boundary + lineEnd);
        dos.writeBytes("Content-Disposition: form-data; name=\"myFile\";filename=\""+file.getName()+"\"" + lineEnd);
        dos.writeBytes(lineEnd);

        // create a buffer of  maximum size
        bytesAvailable = fileInputStream.available();

        bufferSize = Math.min(bytesAvailable, maxBufferSize);
        buffer = new byte[bufferSize];

        // read file and write it into form...
        bytesRead = fileInputStream.read(buffer, 0, bufferSize); 

        while (bytesRead > 0) {
            dos.write(buffer, 0, bufferSize);
            bytesAvailable = fileInputStream.available();
            bufferSize = Math.min(bytesAvailable, maxBufferSize);
            bytesRead = fileInputStream.read(buffer, 0, bufferSize);  
        }

        // send multipart form data necesssary after file data...
        dos.writeBytes(lineEnd);
        dos.writeBytes(twoHyphens + boundary + twoHyphens + lineEnd);

        // Responses from the server (code and message)
        int serverResponseCode = conn2.getResponseCode();
        String serverResponseMessage = conn2.getResponseMessage();
        //we are expecting another redirect here
        log("aaaargh! 400 instead of 302! "+serverResponseCode+" to "+conn2.getHeaderField("Location"));
    }catch (IOException e)  {
        log(e.getMessage());
        throw e;
    }catch(Exception e) {
        log(e.getMessage());
        throw new IOException(e);
    }   finally {
        //close the streams //
        if (dos!=null)  {   
            try {
                dos.flush();
                dos.close();
            }catch(IOException ioe){}
        }
        if (fileInputStream!=null)
            try {
                fileInputStream.close();
            }catch(IOException ioe){}

        if (conn!=null )
            try {
                conn.disconnect();
            }catch(Exception ioe){}

        if (conn2!=null)
            try {
                conn2.disconnect();
            }catch(Exception ioe){}

    }
}

注意，上面的serverResponseMessage字符串从生产blobstore作为“错误请求”返回

Answer 1

我不知道如何从Android客户端执行此操作，但是可以向您展示我们如何从javascript客户端执行操作，因为它可能会为您提供一些指导。

客户端非常简单（这是angular.js控制器），我们获得要使用的URL并上传到该URL

// model file upload
    $scope.onFileSelect = function ($files) {
        $scope.uploadStatus = 'loading';
        for (var i = 0; i < $files.length; i++) {
            var file = $files[i];
            console.log(file);

            $http.get('/endpoints/prototype/' + $scope.prototype.key + '/file/url')
                .success((function (data) {
                        console.log(data);

                        $scope.upload = $upload.upload({
                            url: data,
                            withCredentials: true,
                            file: file
                        })
                        .success(function (data) {
                            console.log(data);
                            $scope.prototype.modelFile = data;
                        })
                        .error(function (data, status) {
                            console.error(data);
                            $scope.uploadStatus = 'error';
                            $scope.uploadError = status;
                        });
                }))
                .error((function (data, status) {
                    console.error(data);
                    $scope.uploadStatus = 'error';
                    $scope.uploadError = status;
                }));
        }
    };

服务器端，我们有一个端点，该端点返回用于发布的URL（这是一个Spring MVC控制器）。 请注意，我们在createUploadUrl（）中指定成功路径

@RequestMapping(value = "/endpoints/prototype/{key}/file/url", method = RequestMethod.GET)
@ResponseBody
public String getFileUploadUrl(@PathVariable("key") String prototypeKey) {
    final UploadOptions uploadOptions = Builder.withDefaults()
          .googleStorageBucketName("palmyra-prototype-store");

    return blobstoreService.createUploadUrl("/endpoints/prototype/" + prototypeKey + "/file", uploadOptions);
}

最后，上传成功后调用的端点成功

@RequestMapping(value = "/endpoints/prototype/{key}/file", method = RequestMethod.POST)
@ResponseBody
public String handleFileUpload(@PathVariable("key") String prototypeKey, HttpServletRequest request) {
    final Map<String, List<BlobKey>> blobs = blobstoreService.getUploads(request);
    final Map<String, List<FileInfo>> allFileInfos = blobstoreService.getFileInfos(request);

    final List<BlobKey> blobKeys = blobs.get(INPUT_FILE_NAME);
    final List<FileInfo> fileInfos = allFileInfos.get(INPUT_FILE_NAME);

    if ((blobKeys == null) || (fileInfos == null)) {
        return "You failed to upload a model file for " + prototypeKey + " because the file was empty.";
    } else if ((blobKeys.size() == 1) && (fileInfos.size() == 1)) {
        final BlobKey blobKey = blobKeys.get(0);
        final FileInfo fileInfo = fileInfos.get(0);

        final Prototype prototype = prototypeService.findByKey(prototypeKey);
        prototype.setModelFile(blobInfoFactory.loadBlobInfo(blobKey).getFilename());
        prototype.setUploadedModelFile(fileInfo.getGsObjectName());

        prototypeService.updatePrototype(prototypeKey, prototype);

        return blobInfoFactory.loadBlobInfo(blobKey).getFilename();
    } else {
        return "One and only one file is allowed to be uploaded. The related prototype is " + prototypeKey +
              ". The number of blobs is " + blobKeys.size() + ", the number of files is " + fileInfos.size();
    }
}

就是这样，希望它可以帮助您解决问题。

Answer 2

我通过使用较高级别的API而不是尝试使用的较低级别的HttpConnection代码来解决此问题。

    public String uploadFile(String url, File f) throws Exception   {
    HttpClient httpClient = new DefaultHttpClient();    
    String str = "";
    HttpPost first = new HttpPost(url);  //a GET should work but I was getting 405
    HttpResponse firstResponse = httpClient.execute(first);
    str = firstResponse.getFirstHeader("Location").getValue();
    //Post image to generated url
    HttpPost second = new HttpPost(str);
    FileBody fileBody = new FileBody(f);
    MultipartEntity reqEntity = new MultipartEntity();
    reqEntity.addPart("file", fileBody);
    second.setEntity(reqEntity);
    httpClient = new DefaultHttpClient();
    HttpResponse secondResponse = httpClient.execute(second); 
    str = secondResponse.getFirstHeader("Location").getValue();
    log(str);
    return str;
}

此方法返回上载图像的服务URL。