java - 如何从谷歌驱动器读取大文件到 gae blobstore

Question

这是我目前用于将文件从 google drive 读取到 google app engine 的 blobstore 的代码。

private BlobKey getBlobKey(File f, DriveObject driveObject)
            throws IOException, MalformedURLException { 

        Drive service = ((GoogleDrive) driveObject).getService();

        byte[] buffer = new byte[(int) f.getFileSize().intValue()];
        GenericUrl url = new GenericUrl(f.getDownloadUrl());
        HttpResponse response = service.getRequestFactory()
                    .buildGetRequest(url).execute();

        InputStream is = response.getContent();

        FileService fileService = FileServiceFactory.getFileService();
        AppEngineFile file = null;
        boolean lock = true;
        try {
            file = fileService.createNewBlobFile("application/zip");
            FileWriteChannel writeChannel = fileService.openWriteChannel(
                        file, lock);

            int len;
            while ((len = is.read(buffer)) >= 0) {
            ByteBuffer bb = ByteBuffer.wrap(buffer, 0, len);
            writeChannel.write(bb);
            }
            writeChannel.closeFinally();

        } catch (IOException e) {
                // TODO Auto-generated catch block
            e.printStackTrace();
        }

            BlobKey bk = fileService.getBlobKey(file);

        return bk;
    }

这适用于小文件，但如果文件大于 ~25MB，则会出错。有没有更好的方法来完成我想做的事情？

这是我看到的错误

Uncaught exception from servlet
com.google.appengine.api.urlfetch.ResponseTooLargeException: The response from url https://doc-0o-bs-docs.googleusercontent.com/docs/securesc/97o44sjeam7f23b1flie9m3qqidhrago/97q4akk8bmpub24itqhclo1vakjusu84/1368259200000/14350098165097390874/14350098165097390874/0ByS2XCxCEzq-NUVuajAwWGVoR1U?h=16653014193614665626&e=download&gd=true was too large.
    at com.google.appengine.api.urlfetch.URLFetchServiceImpl.convertApplicationException(URLFetchServiceImpl.java:132)
    at com.google.appengine.api.urlfetch.URLFetchServiceImpl.fetch(URLFetchServiceImpl.java:43)
    at com.google.apphosting.utils.security.urlfetch.URLFetchServiceStreamHandler$Connection.fetchResponse(URLFetchServiceStreamHandler.java:417)
    at com.google.apphosting.utils.security.urlfetch.URLFetchServiceStreamHandler$Connection.getInputStream(URLFetchServiceStreamHandler.java:296)
    at com.google.apphosting.utils.security.urlfetch.URLFetchServiceStreamHandler$Connection.getResponseCode(URLFetchServiceStreamHandler.java:149)
    at com.google.api.client.http.javanet.NetHttpResponse.<init>(NetHttpResponse.java:37)
    at com.google.api.client.http.javanet.NetHttpRequest.execute(NetHttpRequest.java:95)
    at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:980)

我应该补充一点

Drive service = ((GoogleDrive) driveObject).getService();

返回

new Drive.Builder(httpTransport, jsonFactory, cred)
            .build()

Answer 1

您可以从云端硬盘分块下载文件。使用 Range下载请求中的 header ，如 Google Drive documentation 中所述.

Range: bytes=500-999