我想从jsp文件中调用servlet中的某个方法，但我不知道该怎么做。
以下是jsp：

imageUpload user = new imageUpload();
    out.println(clicked);

    String img = request.getParameter("picture");
    user.insertProfPic(request, response, id, img);

下面是servlet：

public class imageUpload extends HttpServlet implements insertToDB{

    private static final String SAVE_DIR = "uploads";
    public String dbFileName = "";
    java.sql.Date sqlDate = new java.sql.Date(new java.util.Date().getTime());

    @Override
    public void insertProfPic(HttpServletRequest request, HttpServletResponse response, int user_id, String file) throws IOException, ServletException {
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();

        Part part = request.getPart(file);//
        String fileName = extractFileName(part);//file name

        String applicationPath = getServletContext().getRealPath("");

        String uploadPath = applicationPath + File.separator + SAVE_DIR;
        System.out.println("applicationPath:" + applicationPath);
        File fileUploadDirectory = new File(uploadPath);
        if (!fileUploadDirectory.exists()) {
            fileUploadDirectory.mkdirs();
        }
        String savePath = uploadPath + File.separator + fileName;
        System.out.println("savePath: " + savePath);
        String sRootPath = new File(savePath).getAbsolutePath();
        System.out.println("sRootPath: " + sRootPath);
        part.write(savePath + File.separator);
        File fileSaveDir1 = new File(savePath);

        dbFileName = SAVE_DIR + File.separator + fileName;
        part.write(savePath + File.separator);

        try {
            Connection conn = DatabaseConnection.getCon();
            String query = "insert into images(user_id, images) values(?,?)";
            PreparedStatement pst = conn.prepareStatement("");
            pst.setInt(1, user_id);
            pst.setString(2, dbFileName);

            pst.executeUpdate();
            out.println("<center><h1>Image inserted Succesfully......</h1></center>");
            out.println("<center><a href='display.jsp?id=" + user_id + "'>Display</a></center>");
        } catch (Exception e) {
            out.println(e);
        }

    }

    private String extractFileName(Part part){
        String contentDisp = part.getHeader("content-disposition");
        String[] items = contentDisp.split(";");
        for(String s : items){
            if(s.trim().startsWith("filename")){
                return s.substring(s.indexOf("=") + 2, s.length() - 1);
            }
        }
        return "";
    }
}

我的dopost方法是空的，我试图从jsp文件调用insertprofpic方法。当我尝试时，它只会给我一个内部服务器错误