java pass data from servelt to jsp

Question

I alreayd saw many questions about this but it the proposed solutions didn't work for me:

In my servlet i do this:

protected void doGet(HttpServletRequest request,
        HttpServletResponse response) throws ServletException, IOException {
        request.setAttribute("title", "Level0and1ForUser");

        request.getRequestDispatcher("./testPages/resultSetFormatter.jsp")
                .forward(request, response);
    }
}

And in the jsp page:

<title>
<%= request.getParameter("title") %>
</title>

the result is null as you see:

You are writing the value into an *attribute*, then you are trying to read a *parameter*. That's not the same thing. — f1sh, Apr 04 '16 at 11:33

score 2 · Accepted Answer · edited May 23 '17 at 11:50

2

You can use:

${requestScope.title}

NOTE:

Never use java code inside a jsp page, its deprecated and highly discouraged

The usage of scriptlets is always discouraged. Instead one should use tag libs like JSTL or Expression Language (EL).

The question always arises that why should we not use scriptlets in JSP when the same task can be performed using scriptlets as well.

Here is why one should avoid using scriplets in JSPs:

JSP Scriptlets reduces the maintainability and readibility of the code and hence making it difficult to read and make further changes.

JSP Scriptlets can not be re-used.

JSP Scriptlets are not unit-testable.

JSP Scriplets merge the presentation with business logic which is highly prone to errors.

Last but not least, if JSP Scriptlets throws an exception, it breaks the whole page there and doesn’t move further in the processing.

edited May 23 '17 at 11:50

Community

1
1

answered Apr 04 '16 at 11:30

Jordi Castilla

26,609
8
70
109

and what is the possible (better) alternative to my code please ? – Ania David Apr 04 '16 at 12:02
Second line of my answer... Just place it between `` tags – Jordi Castilla Apr 04 '16 at 12:04
well the title becomes `{$requestScope.title}` not the actual value of the title, this is the code ` {$requestScope.title} ` – Ania David Apr 04 '16 at 12:09
Wow dude, you just had to copy a single line... Please double check to see typo ;) – Jordi Castilla Apr 04 '16 at 12:10
I am sorry, thank you – Ania David Apr 04 '16 at 12:12
My apologizes! Corrected comment and glad to help. Please read the posts about why not use scriptlets, if you are starting with jsp better do it with the right technologies ;) – Jordi Castilla Apr 04 '16 at 12:15
please is the same for other variables? for example when I send a `Map` object from my servlet to my jSP, how can I retrive it? (so I can make loop over it in my JSP ) ? really thanks – Ania David Apr 04 '16 at 12:15
Yes I am reading them right now , – Ania David Apr 04 '16 at 12:16
Yes with primitive types (string, int, long...) but for Collections or your own ojects you need to convert them using json – Jordi Castilla Apr 04 '16 at 12:17
so I should convert my map to JSON in my servlet and send that JSON to my jsp where I loop over it ? – Ania David Apr 04 '16 at 12:20
Yes, but iterate is more for lists or arrays, you might get map info without iterate with a javascript json library – Jordi Castilla Apr 04 '16 at 12:30

score 1 · Answer 2 · edited Apr 04 '16 at 11:34

1

if you put the value in an attribute of the request, you have to get it in the same way:

<title>
<%= (String)request.getAttribute("title") %>
</title>

but much more beautiful is Jordi's answer.

edited Apr 04 '16 at 11:34

f1sh

11,489
3
25
51

answered Apr 04 '16 at 11:26

nano_nano

12,351
8
55
83

java pass data from servelt to jsp

2 Answers2

NOTE: