【发布时间】：2020-11-05 15:16:19
【问题描述】：
tl;dr:如何让 Google Cloud Vision OCR 在 Cloud Shell 编辑器的本地主机上工作？
我正在使用Google Cloud Shell editor，它包含一个web preview 功能，可以在https://8080-dot-10727374-dot-devshell.appspot.com/index.html 等URL 上为“本地”网络服务器提供服务。
我正在关注 Cloud Vision OCR 的 this tutorial。我将该示例代码放入使用 Blobstore 作为图像主机的 servlet：
package com.google.servlets;
import com.google.appengine.api.blobstore.BlobInfo;
import com.google.appengine.api.blobstore.BlobInfoFactory;
import com.google.appengine.api.blobstore.BlobKey;
import com.google.appengine.api.blobstore.BlobstoreService;
import com.google.appengine.api.blobstore.BlobstoreServiceFactory;
import com.google.appengine.api.images.ImagesService;
import com.google.appengine.api.images.ImagesServiceFactory;
import com.google.appengine.api.images.ServingUrlOptions;
import com.google.cloud.vision.v1.AnnotateImageRequest;
import com.google.cloud.vision.v1.AnnotateImageResponse;
import com.google.cloud.vision.v1.BatchAnnotateImagesResponse;
import com.google.cloud.vision.v1.Feature;
import com.google.cloud.vision.v1.Image;
import com.google.cloud.vision.v1.ImageAnnotatorClient;
import com.google.cloud.vision.v1.ImageSource;
import com.google.cloud.vision.v1.TextAnnotation;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
* When the user submits the form, Blobstore processes the file upload and then forwards the request
* to this servlet. This servlet can then analyze the image using the Vision API.
*/
@WebServlet("/image-analysis")
public class ImageAnalysisServlet extends HttpServlet {
@Override
public void doPost(HttpServletRequest request, HttpServletResponse response) throws IOException {
PrintWriter out = response.getWriter();
// Get the BlobKey that points to the image uploaded by the user.
BlobKey blobKey = getBlobKey(request, "image");
// Get the URL of the image that the user uploaded.
String imageUrl = getUploadedFileUrl(blobKey);
// Extract text from the image
String text = detectDocumentText(imageUrl);
// Output some HTML.
response.setContentType("text/html");
out.println("<p>Here's the image you uploaded:</p>");
out.println("<a href=\"" + imageUrl + "\">");
out.println("<img src=\"" + imageUrl + "\" />");
out.println("</a>");
out.println("<h1>text: " + text + "</h1>");
}
/**
* Returns the BlobKey that points to the file uploaded by the user, or null if the user didn't
* upload a file.
*/
private BlobKey getBlobKey(HttpServletRequest request, String formInputElementName) {
BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();
Map<String, List<BlobKey>> blobs = blobstoreService.getUploads(request);
List<BlobKey> blobKeys = blobs.get("image");
// User submitted form without selecting a file, so we can't get a BlobKey. (dev server)
if (blobKeys == null || blobKeys.isEmpty()) {
return null;
}
// Our form only contains a single file input, so get the first index.
BlobKey blobKey = blobKeys.get(0);
// User submitted form without selecting a file, so the BlobKey is empty. (live server)
BlobInfo blobInfo = new BlobInfoFactory().loadBlobInfo(blobKey);
if (blobInfo.getSize() == 0) {
blobstoreService.delete(blobKey);
return null;
}
return blobKey;
}
/** Returns a URL that points to the uploaded file. */
private String getUploadedFileUrl(BlobKey blobKey) {
ImagesService imagesService = ImagesServiceFactory.getImagesService();
ServingUrlOptions options = ServingUrlOptions.Builder.withBlobKey(blobKey);
String url = imagesService.getServingUrl(options);
// GCS's localhost preview is not actually on localhost,
// so make the URL relative to the current domain.
if(url.startsWith("http://localhost:8080/")){
url = url.replace("http://localhost:8080/", "https://8080-dot-10727374-dot-devshell.appspot.com/");
}
return url;
}
private String detectDocumentText(String path) throws IOException {
List<AnnotateImageRequest> requests = new ArrayList<>();
ImageSource imgSource = ImageSource.newBuilder().setImageUri(path).build();
Image img = Image.newBuilder().setSource(imgSource).build();
Feature feat = Feature.newBuilder().setType(Feature.Type.DOCUMENT_TEXT_DETECTION).build();
AnnotateImageRequest request = AnnotateImageRequest.newBuilder().addFeatures(feat).setImage(img).build();
requests.add(request);
// Initialize client that will be used to send requests. This client only needs to be created
// once, and can be reused for multiple requests. After completing all of your requests, call
// the "close" method on the client to safely clean up any remaining background resources.
try (ImageAnnotatorClient client = ImageAnnotatorClient.create()) {
BatchAnnotateImagesResponse response = client.batchAnnotateImages(requests);
List<AnnotateImageResponse> responses = response.getResponsesList();
client.close();
// Check to see if any of the responses are errors
for (AnnotateImageResponse res : responses) {
if (res.hasError()) {
System.out.format("Error: %s%n", res.getError().getMessage());
return "Error: " + res.getError().getMessage();
}
// For full list of available annotations, see http://g.co/cloud/vision/docs
TextAnnotation annotation = res.getFullTextAnnotation();
return annotation.getText();
}
}
catch(Exception e) {
return "ERROR: ImageAnnotatorClient Failed, " + e;
}
// Case where the ImageAnnotatorClient works, but there are no responses from it.
return "Error: No responses";
}
}
当我使用mvn package appengine:deploy 命令部署到真实服务器时，这非常有效：
（嗯，正如从这张测试图片中可以预期的那样完美。）
但是，如果我使用 mvn package appengine:run 命令部署到“本地”开发服务器，则 Google Cloud Vision 会返回一般的“错误图像数据”错误：
我猜这是因为图像 URL (https://8080-dot-10727374-dot-devshell.appspot.com/_cloudshellProxy/_ah/img/TjxgeYiHlCkix-XRj94jnw) 无法公开访问，因为它运行在“假”本地主机上，需要我登录到我的 Google 帐户才能查看。
如何让 Google Cloud Vision OCR 在 Cloud Shell 编辑器的“假”本地主机上工作？
【问题讨论】：
标签： java google-app-engine blobstore google-cloud-vision google-cloud-shell