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sendRedirect with passing some values.

Vinoth Thirunavukarasu
Ranch Hand

Joined: Dec 18, 2008
Posts: 164

Hi,
I'm using a servlet to check whether the userName and password are exist if it is false I have to redirect to the login page with some message like "Invalid user name or password".
Now I used session.setAttribute("error",msg);
Is there any other way to pass error message to login page.


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Bauke Scholtz
Ranch Hand

Joined: Oct 08, 2006
Posts: 2458
You can use a request parameter for that. You can just do a forward instead of redirect.
Steve Luke
Bartender

Joined: Jan 28, 2003
Posts: 4181
    
  21

You can pass the error to the next page as a url parameter:
String url = "/login?error="+URLEncoder.encode("Invalid Username or Password", "UTF-8");
The URLEncoder is needed to encode spaces so they don't break the URL.

A way to make passing the parameter easier is to store the possible errors in a central location with a lookup table. You would use a basic lookup value (like an integer) as a key for the lookup value, which simplifies the URL from:
/login?error=Invalid+Username+or+Password
to
/login?error=1

Here is an example below. Note that I don't have the webapp where I used this with me and I haven't done servlet/jsp programming in a few months so I am likely making mistakes, so take it as a guideline.

Central store for the error messages

Somewhere early in the webapp, like a context listener

In the Servlet that detects the error and does the forward

In the JSP that displays the login form:

[ December 19, 2008: Message edited by: Steve Luke ]

Steve
Knaresh Gupta
Greenhorn

Joined: Nov 22, 2008
Posts: 5
Hello you can simple write the HTML Code in else part like this
out.println("<li><i>we con't find the username/password provided by you</i></li>");
return;

it simply display the message in browser and automatically come back.
 
It is sorta covered in the JavaRanch Style Guide.
 
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