通过Servlet将文件从HTML表格上传到Google云端存储(使用Google Cloud Storage Client Library for Java)

Question

通过Servlet将文件从HTML表格上传到Google云端存储(使用Google Cloud Storage Client Library for Java)

Aer*_*rox 3 html java eclipse google-app-engine google-cloud-storage

我的项目是由GAE Plugin for Eclipse(没有Maven)创建的,我发布的代码由以下组成:

针对home.jsp

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
    <head>
    <title>Upload Test</title>
    </head>
    <body>
        <form action="/upload" method="post" name="putFile" id="putFile"
                enctype="multipart/form-data">
                <input type="file" name="myFile" id="fileName">
                <input type="submit" value="Upload">
        </form> 
    </body>
    </html>

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UploadServlet.java:

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.nio.channels.Channels;
import java.util.Enumeration;
import java.util.logging.Logger;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.FileItemIterator;
import org.apache.commons.fileupload.FileItemStream;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import com.google.appengine.tools.cloudstorage.GcsFileOptions;
import com.google.appengine.tools.cloudstorage.GcsFilename;
import com.google.appengine.tools.cloudstorage.GcsOutputChannel;
import com.google.appengine.tools.cloudstorage.GcsService;
import com.google.appengine.tools.cloudstorage.GcsServiceFactory;
import com.google.appengine.tools.cloudstorage.RetryParams;

public class UploadServlet extends HttpServlet {

    private static final Logger log = Logger.getLogger(UploadServlet.class.getName());

    private final GcsService gcsService = GcsServiceFactory.createGcsService(new RetryParams.Builder()
    .initialRetryDelayMillis(10)
    .retryMaxAttempts(10)
    .totalRetryPeriodMillis(15000)
    .build());

    private String bucketName = "myBucketNameOnGoogleCloudStorage";

    /**Used below to determine the size of chucks to read in. Should be > 1kb and < 10MB */
      private static final int BUFFER_SIZE = 2 * 1024 * 1024;

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

        String sctype = null, sfieldname, sname = null;
        ServletFileUpload upload;
        FileItemIterator iterator;
        FileItemStream item;
        InputStream stream = null;
        try {
            upload = new ServletFileUpload();
            res.setContentType("text/plain");

            iterator = upload.getItemIterator(req);
            while (iterator.hasNext()) {
                item = iterator.next();
                stream = item.openStream();

                if (item.isFormField()) {
                    log.warning("Got a form field: " + item.getFieldName());
                } else {
                    log.warning("Got an uploaded file: " + item.getFieldName() +
                            ", name = " + item.getName());

                    sfieldname = item.getFieldName();
                    sname = item.getName();

                    sctype = item.getContentType();

                    GcsFilename gcsfileName = new GcsFilename(bucketName, sname);

                    GcsFileOptions options = new GcsFileOptions.Builder()
                    .acl("public-read").mimeType(sctype).build();

                    GcsOutputChannel outputChannel =
                            gcsService.createOrReplace(gcsfileName, options);

                    copy(stream, Channels.newOutputStream(outputChannel));

                    res.sendRedirect("/");
                }
            }
        } catch (Exception ex) {
            throw new ServletException(ex);
        }
    }

    private void copy(InputStream input, OutputStream output) throws IOException {
        try {
          byte[] buffer = new byte[BUFFER_SIZE];
          int bytesRead = input.read(buffer);
          while (bytesRead != -1) {
            output.write(buffer, 0, bytesRead);
            bytesRead = input.read(buffer);
          }
        } finally {
          input.close();
          output.close();
        }
      }

}

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我还尝试使用upload.setMaxSize(-1)设置Upload的maximumSize; 或者将BUFFER_SIZE从2*1024*1024更改为200*1024*1024,但问题仍然存在.更具体地说,当上传达到100%时,我会在网页上收到此消息:

Error: Request Entity Too Large Your client issued a request that was too large.

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如何使用JAVA和Google Cloud Storage Client Library for Java解决这个问题？(我不打算用其他编程语言彻底改变项目)

你能帮我找一个解决方案吗？非常感谢!

Answer 1

ale*_*lex 6

App Engine请求限制为32Mb.这就是当您发送> 32Mb的文件时上传失败的原因.结帐配额和限额部分.

您有两种上传文件> 32Mb的选项:

Blobstore API.您可以指定GCS存储桶,而不是使用Blobstore存储空间.

要做那个使用createUploadUrl(java.lang.String successPath, UploadOptions uploadOptions)方法BlobstoreService.

这是一个示例应用程序:https://github.com/crhym3/java-blobstore-gcs-sample
GCS的签名URL功能

或者您可以使用Google云端硬盘并仅在数据存储区中存储文档ID :)

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