iText“找不到文件或资源”错误

Question

我遇到问题“<file_name>.pdf not found as file or resource”代码从选择的路径上传文件到数据库。以下是我使用的代码： 它读取PDF文件并作为CLOB上传到DB。然而，它应该是一项简单的任务，由于某些原因它无法正常工作。

public class FileUpload extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public FileUpload() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        doPost(request,response);
    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
         String uploadData="";
         BusinessLogic bl=new BusinessLogic();
         String user=(String) request.getSession().getAttribute("UserName");
         //InputStream inputStream = null;  

         String fileName = request.getParameter("file");
         File file = new File(fileName);
         try {
           // Load an existing document
             PdfReader reader = new PdfReader(fileName);            
             int n = reader.getNumberOfPages();
             /*for (int i=1;i<=n;i++)
             {*/
                 /*String str=PdfTextExtractor.getTextFromPage(reader, i);*/
             String str=PdfTextExtractor.getTextFromPage(reader, 2);
             uploadData=uploadData+str;
             /*}*/
             bl.updateAckFile(file,uploadData,user);

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

         /*File file = new File(fileName);
         FileInputStream fis = new FileInputStream(file);
         bl.updateAckFile(file,fis,user);*/
         RequestDispatcher rd = request.getRequestDispatcher("/AcknowFile.jsp");        
         rd.forward(request, response);

    }

}

非常感谢您提供任何帮助。