如何修复HTTP 500错误并且Blob文件未上传

Question

在jsp和servlet的

post和doPost中。不能正常工作，而是获取并且服务正常工作。 而且Blob图片文件也没有上传。

jsp代码：

<form  method="post" enctype="multipart/form-data" action="insertbooks">

servlet代码：

protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");


//retrieving image
        InputStream inputStream = null; // input stream of the upload file

        String Title = request.getParameter("title");

         // obtains the upload file part in this multipart request
        Part filePart = request.getPart("image");
        if (filePart != null) {
            // prints out some information for debugging
            System.out.println(filePart.getName());
            System.out.println(filePart.getSize());
            System.out.println(filePart.getContentType());

            // obtains input stream of the upload file
            inputStream = filePart.getInputStream();

              pw.println("Got photooo");
        }


        String Author = request.getParameter("author");
        String Price = request.getParameter("price");

        float Pricef = Float.valueOf(Price);
          pw.println("Got parameters");




Connection conn = null;
    Statement stmt = null;

      try{
            Class.forName("com.mysql.cj.jdbc.Driver");

      pw.println("Driver Loaded");
      conn = DriverManager.getConnection(dbURL, dbUser, dbPass); 
      pw.println("Connection Established_1");
      stmt = conn.createStatement();

     // String query = "Insert into books(title,image,author,price) values('"+Title +"','"+inputStream +"','"+Author+"','"+Pricef +"')" ;
     String query = "Insert into books(title,image,author,price) values(?,?,?,?)" ;

     PreparedStatement ps =conn.prepareStatement(query);
     ps.setNString(1,Title);
     if(inputStream != null){
     // fetches input stream of the upload file for the blob column
     ps.setBinaryStream(2, inputStream);
     }
     ps.setNString(3,Author);
     ps.setFloat(4, Pricef);



     // Sends the statement to the database server
     int row= ps.executeUpdate();
     if(row>0){
     pw.println("data inserted");

     }


     /*int row = stmt.executeUpdate(query);
            if (row > 0) {

                pw.println("Data Inserted");
            }  */


      } catch (SQLException ex) {
             ex.getMessage();
          //  ex.printStackTrace();
          ex.printStackTrace(pw);
            pw.println("Connection not Established_1");
        } catch (ClassNotFoundException ex) {
            Logger.getLogger(insertbooks.class.getName()).log(Level.SEVERE, null, ex);
        } finally {
            if (conn != null) {
                // closes the database connection
                try {
                    conn.close();
                } catch (SQLException ex) {
                    ex.printStackTrace();
                }
            }

            System.out.println("Successfully");
            // sets the message in request scope
          //  request.setAttribute("message", message);

            // forwards to the message page
           // getServletContext().getRequestDispatcher("/message.jsp").forward(request, response);
        }

    pw.close();
    }
}

错误：

HTTP状态500- 输入例外报告

消息

说明服务器遇到内部错误，导致服务器无法执行   完成此请求。

例外

java.lang.NullPointerException
 sun.misc.FloatingDecimal.readJavaFormatString(FloatingDecimal.java:1838)
  sun.misc.FloatingDecimal.parseFloat(FloatingDecimal.java:122)
  java.lang.Float.parseFloat(Float.java:451)
  java.lang.Float.valueOf(Float.java:416)
  insertbooks.doPost(insertbooks.java:63)
  javax.servlet.http.HttpServlet.service(HttpServlet.java:646)
  javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
  org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)