Convert a Part to File and Read Excel File

I am uploading an excel file to a servlet and trying to read its content. I am able to upload and send the file to the servlet. Over at the servlet, I am able to get the upload as a Part and read its name, file size and content type correctly. But how do I use this 'Part' to read as a file?

I am trying to use POI to read the Excel file. It requires me to pass in a file thus I passed in the 'Part' and cast it as a File. At runtime it returns an exception telling me that casting is not allowed.

I don't see a request.getFile option. Is there anyway to come around to make that Part into a File? Or another way to request File instead of Part. Please advice.

 <!-- HTML -->
    <form method="post" action="MyServlet" enctype="multipart/form-data">
        <input type="file" name="file" id="file">
        <button type="submit">Send</button>
    </form>

    //Servlet
public class ExcelUploadServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request,
                          HttpServletResponse response) throws ServletException, IOException {

        Part filePart = request.getPart("file");

        if (filePart != null) {
            // These prints out the correct data
            System.out.println(filePart.getName());
            System.out.println(filePart.getSize());
            System.out.println(filePart.getContentType());
        }


        //Need to read excel file as follows  but how do I call the filepart here? 
        FileInputStream fis  = new FileInputStream((File)filePart);//cast doesn't work
        HSSFWorkbook wb  = new HSSFWorkbook(fis);
        HSSFSheet sheet = wb.getSheetAt(0);
        for(Row row : sheet){
            for (Cell cell : row){
                System.out.println(cell.getStringCellValue());
            }
        }
    }
}