为什么jsp request.getParameter取不到值，但request.getQueryString()却有值呢
Servlet:
public class StudentLoginSvlt extends HttpServlet {
public void doGet(HttpServletRequest req, HttpServletResponse res)
{
res.sendRedirect("jsp/DisplayCourse.jsp?username=wgy&ww=eee");
}
}


DisplayCourse.jsp:

request.getQueryString() 得到值为：username=wgy&ww=eee;
request.getParameter（"username”）为空
[最优解释]
都重定向了上哪取值。