从jsp中删除'null'文本 [英] remove 'null' text from jsp

问题描述

在我的Login.jsp页面中有

In my Login.jsp page has

<p><%=request.getAttribute("loginMsg") %></p>

line ..用于显示消息。但在显示之前，它会显示null。如何显示我之前显示没有显示'null'的消息？



这里我的servlet中的代码向jsp调用消息。

line..It is for display a message.But before it displays ,it displays 'null'.How can i display message without display 'null' before that?

here my code in servlet which call a message to jsp.

private void loginDetail(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException{
		
		User u = new User();
		UserService us =new UserServiceImpl() ;
		
		String Uname = request.getParameter("txtUname");		
		String Pwrd = request.getParameter("txtPwrd");	
		
		u.setUname(Uname);
		u.setPwrd(Pwrd);
		
		System.out.println(Uname+""+Pwrd);
		try {
			if(us.Userlogin(u.getUname(),u.getPwrd())){
				String message = "Thank you, " + Uname +"..You are now logged into the system";			    
				request.setAttribute("message", message);
				RequestDispatcher rd = getServletContext().getRequestDispatcher("/menu.jsp");
				rd.forward(request, response); 
				HttpSession session = request.getSession(true);
			    session.setAttribute("loggedUser", u);
			    String reqUrl = (String)session.getAttribute("requestedURL");
			    session.removeAttribute("requestedURL");
				response.sendRedirect(reqUrl);				
			}else {
				String message = "You have to register first or check Your user name password again!";				
				request.setAttribute("loginMsg", message);
				RequestDispatcher rd = getServletContext().getRequestDispatcher("/login2.jsp");
				rd.forward(request, response); 
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block			
			e.printStackTrace();
		}
	}

请告诉我哪里出错了以及如何解决？



先谢谢你！

Please tell me where i go wrong and how to fix it?

Thank you in Advance!

推荐答案

在jsp中使用if else语句以避免显示空值



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Use if else statements in jsp to avoid displaying null values

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