session().getAttribute返回null [英] session().getAttribute is returning null

问题描述

我有一个servlet，它调用jsp页面. 在servlet中，我正在正确检索登录名提供的用户名. 但是在会话中设置了相同的值之后，当我访问被调用的jsp页面时，其返回null.

I have a servlet which calls a jsp page. In the servlet I am retrieving the username provided at the login correctly. But after setting the same in session, when i access the called jsp page, its returning null.

public class AdminServlet extends HttpServlet {
/**
 * 
 */
private static final long serialVersionUID = -4244742541587179390L;

public void doGet(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    String userName =  request.getParameter("name");
    System.out.println("UserName: " + userName); // Here it prints the username properly
    request.getSession(true).setAttribute(request.getParameter("name"), userName );
    RequestDispatcher rd = request.getRequestDispatcher("upload.jsp");
    rd.forward(request, response);
//  response.sendRedirect("upload.jsp");
}

public void doPost(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {
    doGet(request,response);
}
}

我正在访问此代码的JSP代码段:

JSP Code snippet where I am accessing this:

<label class="message">Welcome <%= session.getAttribute("userName") %></label>

我在这里做错了什么?谁能帮忙

What am I doing wrong here? Can anyone help please

推荐答案

我认为您颠倒了两个参数.应该是这样的:

I think you inverted the two params. It should be like this:

   request.getSession(true).setAttribute("userName", userName );

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