How to get uploaded excel file from blobstore and how to assign that file to FileInputStream

Question

I am working on project using GWT Java. I uploaded excel file into blobstore in google app engine. I want to read excel file from blobstore. So I have to assign the that excel file from blobstore to FileInputStream.

Example:

 FileInputStream file = new FileInpuStream("what is path shall i provide here")  

What are the possible ways to assign that excel file from blobstore to FileInputStream? Any help?

Thanks in Advance

Answer 1

You can use the Apache POI to open the Excel File using your FileInputStream with for example:

XSSFWorkbook wb = new XSSFWorkbook(new FileInputStream(<whatever>));

and work with the POI API to modify the Excelsheet or get the cellinfos. More information to Apache POI: click here .

Or to see a similar problem on SO: click here

Answer 2

The Apache POI XSSFWorkbook accepts either a File or an InputStream . Assuming that you can access your Blob object via BlobstoreInputStream instance, you can call:

 // BlobKey blobKey = initialize your blob key
 XSSFWorkbook wb = new XSSFWorkbook(new BlobstoreInputStream(blobKey));

You can access the Blobstore via:

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

    @Override
    public void doPost(HttpServletRequest req, HttpServletResponse res)
        throws ServletException, IOException {
        Map<String, List<BlobKey>> blobs = blobstoreService.getUploads(req);
        List<BlobKey> blobKeys = blobs.get("myFile");

        if (blobKeys != null && !blobKeys.isEmpty()) {
            XSSFWorkbook wb = new XSSFWorkbook(new BlobstoreInputStream(blobKeys.get(0)));
        }
    }
}

Further reading: Blobstore Java API Overview