java - 在第二个声明中从 JSP 到 Servlet 获取 Null 值

Question

我在声明 int dept_id = Integer.parseInt(request.getParameter("dept_id")); 时遇到问题，它总是得到 java.lang.NumberFormatException: null。但是 int emp_id 的第一个声明它正在工作，但是对于 dept_id 它总是得到 null 值。

这是我的 Servlet

public UserController() {
    super();
    udao = new UserDao();
    ddao = new DepartmentDao();

}

@Override
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    String forward="";
    String action = request.getParameter("action");

        forward = INSERT_OR_EDIT;
        int emp_id = Integer.parseInt(request.getParameter("emp_id"));
        int dept_id = Integer.parseInt(request.getParameter("dept_id"));


        User user = udao.GetUser(emp_id);
        User user2 = ddao.GetHub(dept_id);

        request.setAttribute("user", user);
        request.setAttribute("user2", user2);



    RequestDispatcher view = request.getRequestDispatcher(forward);
    view.forward(request, response);
}

JSP

<fieldset>
        <legend id="myLegend">User</legend>
<!--        <label for="emp_id">
                Employee ID :
                </label> -->
        <input type="text" readonly="readonly" name="emp_id" style="display:none"
                    value="<c:out value="${user.emp_id}"  />" />


        <label for="serial_number">Serial Number :</label>
                <input type="text" name="serial_number" placeholder="
                    value="<c:out value="${user.serial_number}" />" /><br /><br /> 


            <!--        <label for="dept_id">
                Department ID :
                </label> -->
        <input type="text" readonly="readonly" name="emp_id" style="display:none"
                    value="<c:out value="${user2.dept_id}"  />" />


                <label>Hub :</label>
                <input type="text" name="department_name" 
                    value="<c:out value="${user2.dept_name}" />" /><br /><br /> 



    </fieldset>

Answer 1

您的 dept_id 的名称是 emp_id。它应该看起来像:

<input type="text" readonly="readonly" name="dept_id" style="display:none"
                value="<c:out value="${user2.dept_id}"  />" />

我想你只是忽略了这一点!