java - 如何从Google App Engine访问CSV数据？

我有一个简单的网络应用，可让用户将CSV上传到GAE blob存储。我正在尝试将该数据传递给Google Analytics（分析）API方法，但无法解决。遵循教程文档之后，我似乎只能返回响应头中的文件。

有没有办法将blob作为文件直接传递给方法？

或者，是否可以上传Blob，然后将数据映射到Cloud Storage？

最佳答案

如果您按照此处的代码https://cloud.google.com/appengine/docs/java/blobstore/，它将引导您设置上传URL并提供回调URL，等等。当文件被上传并调用回调URL时，您需要记住Blob键，您可以保存在数据存储区中，将其保留在会话中，或者将其保存在会话中以从数据存储区中读取Blob。

下面的代码应该会有所帮助，特别是您感兴趣的方法是getBlobAsString，或者您可以简单地使用blobStream（BlobstoreInputStream blobStream = new BlobstoreInputStream（blobKey）;）将文件内容作为InputStream传递给周围

在您的Servlet中处理上传回调

import org.apache.commons.io.IOUtils;

import com.google.appengine.api.blobstore.BlobKey;
import com.google.appengine.api.blobstore.BlobstoreInputStream;
import com.google.appengine.api.blobstore.BlobstoreService;
import com.google.appengine.api.blobstore.BlobstoreServiceFactory;

public class Upload extends HttpServlet {
    private BlobstoreService blobstoreService = BlobstoreServiceFactory.getBlobstoreService();

    @Override
    public void doPost(HttpServletRequest req, HttpServletResponse res)
        throws ServletException, IOException {

        Map<String, BlobKey> blobs = blobstoreService.getUploadedBlobs(req);
        BlobKey blobKey = blobs.get("myFile");

        if (blobKey != null) {
            String keyString = blobKey.getKeyString();
            // you can store keyString in the datastore or whatever
            // if you want the call the analytics API then you need the blob as string

             String csv = getBlobAsString(keyString);

             // you can do with csv whatever you like, convert it as an array, etc... then pass it
             // over to the analytic API
        }
    }


   public static String getBlobAsString(String keyString) throws IOException {
        BlobKey blobKey = new BlobKey(keyString);
        BlobstoreInputStream blobStream = new BlobstoreInputStream(blobKey);

        return IOUtils.toString(blobStream, "UTF-8");
    }
 }