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我在接收字节 [] 格式的图像的谷歌应用引擎上运行 servlet。我想使用 POST 请求将此图像保存在谷歌云存储中。

为了得到这个想法,一些代码不起作用但方向正确:

public void postReq( byte[] image) {
    HttpClient httpclient = new DefaultHttpClient();
    HttpPost httpPost = new HttpPost(getUploadUrl());
    FileBody uploadFilePart = new FileBody(?????, "image/jpg");
    MultipartEntity reqEntity = new MultipartEntity();
    reqEntity.addPart("upload-file", uploadFilePart);
    httpPost.setEntity(reqEntity);
    HttpResponse response = httpclient.execute(httpPost);
}

public String getUploadUrl() {
    BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();
    UploadOptions uploadOptions = null;
    String bucket = Constants.BUCKET_NAME;
    uploadOptions = UploadOptions.Builder.withGoogleStorageBucketName(bucket);
    return blobstoreService.createUploadUrl("/upload", uploadOptions);
}

org.apache.http.impl.client.DefaultHttpClient;已弃用,因此显然不是正确的方法。我在互联网上找到的一些东西,但我无法运行它们: http: //knowledge-serve.blogspot.com/2012/09/upload-file-on-google-cloud-storage.html 上传文件 -使用 java.net.URLConnection 触发和处理 HTTP 请求

谷歌做了一些非常好的教程,但用于从 html 页面上传图片: https ://developers.google.com/cloud/samples/photofeed/servephotos

目标是让 POST 请求向谷歌发送多部分/数据,然后谷歌将请求返回给我的 GAE Servlet,在这种情况下是“/上传”。所以我应该这样做,但在 servlet 和 byte[] 图像中:

<form action="<%=serviceManager.getUploadUrl()%>" method="post" enctype="multipart/form-data">
    <input id="input-file" class="inactive file btn" type="file" name="photo" onchange="onFileSelected()">
    <textarea name="title" placeholder="Write a description"></textarea>
    <input id="btn-post" class="active btn" type="submit" value="Post">
    <a class="cancel" onclick="togglePhotoPost(false)">Cancel</a>
</form>
4

2 回答 2

2
 1. Send the image via json from android device to the server. 
 2. register your two servlets. One for seving the image to Blob store and one for downloading the image:


<servlet>
    <servlet-name>UploadHandlerServlet</servlet-name>
    <servlet-class>.servlet.UploadHandlerServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>UploadHandlerServlet</servlet-name>
    <url-pattern>/upload</url-pattern>
</servlet-mapping>
    <servlet>
    <servlet-name>ImagesDownloadServlet</servlet-name>
    <servlet-class>.servlet.ImagesDownloadServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>ImagesDownloadServlet</servlet-name>
    <url-pattern>/download</url-pattern>
</servlet-mapping>

and one more servlet that receives the post request with the image. Lets call it "PhoneServlet"
 3. From PhoneServlet we are making post request this way:



    import java.io.IOException;
    import java.io.OutputStream;
    import java.io.OutputStreamWriter;
    import java.io.PrintWriter;
    import java.io.StringReader;
    import java.net.HttpURLConnection;
    import java.net.MalformedURLException;
    import java.net.URL;
    private void sendMultipartDataPostReq(byte[] imageByteArray, long boundary, String type) throws MalformedURLException, IOException {        
        log.warning("sendMultipartDataPostReq( ) START");
        String charset = "UTF-8";
        String CRLF = "\r\n"; // Line separator required by multipart/form-data.
        HttpURLConnection  connection = (HttpURLConnection)new URL(getUploadUrl()).openConnection();
        connection.setInstanceFollowRedirects(true);
        connection.setDoOutput(true);// fires POST request
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
        PrintWriter writer = null;
        try {
            OutputStream output = connection.getOutputStream();
            writer = new PrintWriter(new OutputStreamWriter(output, charset), true);// true = autoFlush, important! 
            // Send normal param issueId
            writer.append("--" + boundary).append(CRLF);
            writer.append("Content-Disposition: form-data; name=\""+Constants.PARAMETER_TYPE_ISSUEID+"\"").append(CRLF);
            writer.append("Content-Type: text/plain; charset=" + charset).append(CRLF);
            writer.append(CRLF);
            writer.append(Integer.toString(image.getIssueId())).append(CRLF).flush();
            // Send normal param boundary
            writer.append("--" + boundary).append(CRLF);
            writer.append("Content-Disposition: form-data; name=\""+Constants.PARAMETER_TYPE_BOUNDARY+"\"").append(CRLF);
            writer.append("Content-Type: text/plain; charset=" + charset).append(CRLF);
            writer.append(CRLF);
            writer.append(Long.toString(boundary)).append(CRLF).flush();
            // Send normal param type
            writer.append("--" + boundary).append(CRLF);
            writer.append("Content-Disposition: form-data; name=\""+Constants.PARAMETER_TYPE_TYPE+"\"").append(CRLF);
            writer.append("Content-Type: text/plain; charset=" + charset).append(CRLF);
            writer.append(CRLF);
            writer.append(type).append(CRLF).flush();
            // Send binary file.
            writer.append("--" + boundary).append(CRLF);
            writer.append("Content-Disposition: form-data; name=\""+Constants.PARAMETER_TYPE_PHOTO+"\"; filename=\""+ boundary+".jpg" + "\"").append(CRLF);
            writer.append("Content-Type: image/jpg").append(CRLF);
            writer.append("Content-Transfer-Encoding: binary").append(CRLF);
            writer.append(CRLF).flush();
            output.write(imageByteArray);
            output.flush();// Important! Output cannot be closed. Close of writer will close output as well. 
            writer.append(CRLF).flush(); // CRLF is important! It indicates end of binary boundary.
            writer.append("--" + boundary + "--").append(CRLF);// End of multipart/form-data.
            writer.close();
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                log.warning("COnection HTTP_OK");
            } else {
                log.warning("Server returned HTTP error code");
            }
        } catch (Exception e) {
            log.log(Level.SEVERE, e.toString(), e);
        }
        log.warning("sendMultipartDataPostReq( ) END");
    }

 4. This invokes UploadServlet 

        public class UploadHandlerServlet extends HttpServlet {
        private static final long serialVersionUID = 1L;
        private static Logger log = Logger.getLogger(UploadHandlerServlet.class.getName());

        @Override
        public void doPost(HttpServletRequest req, HttpServletResponse res) throws IOException {
            log.warning("UploadHandlerServlet doPost START");
            BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();
            Map<String, List<BlobKey>> blobs = blobstoreService.getUploads(req);
            List<BlobKey> keys = blobs.get(Constants.PARAMETER_TYPE_PHOTO);
            String issueId = req.getParameter(Constants.PARAMETER_TYPE_ISSUEID);
            String type = req.getParameter(Constants.PARAMETER_TYPE_TYPE);
            String boundary = req.getParameter(Constants.PARAMETER_TYPE_BOUNDARY);

            EntityManager em = EMF.get().createEntityManager();
            if (type!=null && type.equals(Constants.IMAGE_TYPE_IMAGE)) {
                log.warning("UploadHandlerServlet doPost: IMAGE_TYPE_IMAGE");
                Issue issue = em.find(Issue.class, Integer.parseInt(issueId));
                //we expect only one image so we get only the first key
                Image image = new Image(issue,keys.get(0).getKeyString(),true, Long.parseLong(boundary));
                em.getTransaction().begin();
                em.persist(image);
                em.getTransaction().commit();
                log.warning("UploadHandlerServlet doPost new Image key is saved");
            }
            else if (type!=null && type.equals(Constants.IMAGE_TYPE_THUMBNAIL)) {
                log.warning("UploadHandlerServlet doPost: IMAGE_TYPE_THUMBNAIL");
                Image image = ImageDAO.getImageByTimeCreated(Long.parseLong(boundary));
                if (image !=null) {
                    image.setBlobKeyThumbnail(keys.get(0).getKeyString());
                    em.getTransaction().begin();
                    em.merge(image);
                    em.getTransaction().commit();
                }
                log.warning("UploadHandlerServlet doPost new Thumbnail key is saved");
            }
            log.warning("UploadHandlerServlet doPost END");
        }
    }

and after UploadHandlerServlet our pictures are in the database as blob keys and in the google BlobStore. 
5. We can download them using the ImagesDownloadServlet:

        public class ImagesDownloadServlet extends HttpServlet {
        private static final long serialVersionUID = 1L;

        @Override
        public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException {
            String blobkeyString = req.getParameter("blobkey");
            if (blobkeyString != null) {
                BlobKey blobKey = new BlobKey(blobkeyString);
                BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();
                blobstoreService.serve(blobKey, res);
            }
            else {
                res.sendError(400, "One or more parameters are not set");
            }
        }
    }

6. The important thing for making the POST request is to use java.net library and nothing else from apache for example to make POST request. All these servlets are on our server. 
于 2013-12-16T16:34:26.550 回答
0

我正在使用 spring MVC servlet 上传文件。以下是 png 文件的示例:

@RequestMapping(value="/gcs/{bucket}/{id}", method = RequestMethod.PUT)
public void doPost(HttpServletRequest req, HttpServletResponse resp) throws    IOException {
  GcsService gcsService =
               GcsServiceFactory.createGcsService(RetryParams.getDefaultInstance());
//  GcsFileOptions go = new GcsFileOptions(Builder.);
  GcsFileOptions options = new    GcsFileOptions.Builder().mimeType("image/png").build();
GcsOutputChannel outputChannel =
    gcsService.createOrReplace(getFileName(req), options);
//outputChannel.write(ByteBuffer.wrap(content));
copy(req.getInputStream(), Channels.newOutputStream(outputChannel));
}

private GcsFilename getFileName(HttpServletRequest req) {
String[] splits = req.getRequestURI().split("/", 4);
if (!splits[0].equals("") || !splits[1].equals("gcs")) {
  throw new IllegalArgumentException("The URL is not formed as expected. " +
      "Expecting /gcs/<bucket>/<object>");
}
return new GcsFilename(splits[2], splits[3]);
} 

然后你可以发送一个 PUT 请求(而不是 POST)到 url /gcs/{your_bucket}/{your_file}

于 2013-10-15T16:30:35.760 回答