On 6/19/2012 10:22 AM, Tim Watts wrote:
Hopefully, you're trying to use or move toward the MVC (Model, View,
Controller) pattern. If not, you should. Google "MVC design pattern".
There are many, many frameworks that will make this easier for you (once
you learn them): Struts, Spring MVC...
If you're well into your project and don't want to add a framework to it
you could write a simple servlet that uses an algorithm to map URI paths
to JSPs then forwards to the JSP using a dispatcher. For instance, you
could put your JSPs in myapp/WEB-INF/jsps. Then have the servlet map a
URI such as /sample to /WEB-INF/jsps/sample.jsp (all relative
to /myapp).
http://localhost:8080/mysite/WEB-INF/jsp/newjsp.jsp
I just created folder jsp under WEB-INF and then added newjsp.jsp(this
is hello world jsp) and then ran the file.I get 404 error. I am trying
all this with netbeans.
Well I hope by now you understand why or we're just going in circles.
Of course, that URL gives a 404: it's trying to access WEB-INF which is
never accessible via HTTP. But it is accessible via
RequestDispatcher.forward() -- e.g.:
servletCtx.getRequestDispatcher("/WEB-INF/jsp/newjsp.jsp").forward(request,
response);
This is kind of like what you said earlier that your servlets are
essentially doing, right?
No I did not do the way you mentioned.I just created a jsp under WEB-INF
and invoked it directly and got 404.I think I now see what you are
mentioning.
and its wonderful idea.Makes perfect sense now.Thanks Tim.
This isn't a great approach because you really aren't separating the
model from the view (all the app logic and display logic are housed in
the JSP -- a maintenance nightmare). But if you don't have time to
re-architect the app now, it will hide the .jsp's from "direct access".
And it will put you in a slightly better position if/WHEN you do
re-architect it.
I think I am using kind of MVC pattern of course the one used around 6
to 8 years back.I am using jsp as view, servlet as kind controller and
then some beans/jstl and el to make my life easy somewhat. I would love
to work with frameworks like spring or struts someday.
They're free you know. :-) But of course, free software doesn't add
hours to the day. You're basically rolling your own MVC and that will
probably help you understand better what these frameworks do. But move
away from this as soon as you can. They've solved a lot of problems you
probably haven't even considered and they can make your applications
much less brittle if you take the time to learn them well.
Yup I have another project in mind which I plan to roll out soon
probably either with spring or JSF.Maybe in a month or 2.I am fast
learner and risk taker.
Ok let me explain as what I need again,
I have form A with say about 10 fields, lets call this as jsp A. So in
browser bar it looks like http://localhost:8080/mysite/A.jsp
Ah, so you do want SOME of your JSPs to be URL accessible! Well, if
A.jsp doesn't and never ever will have any dependencies on the
application's state then fine. Maybe it's true today but I doubt it
will stay that way. So it's probably better to be consistent and hide
this as well.
User fills this A.jsp and then clicks Submit button. It posts the form
to Servlet B which does insert in the database and then forwards the
request via request dispatcher to C.jsp which has some confirmation
details in it.(Unique reference ids pulled out from DB).
So on submit, an HTTP POST is sent to http://localhost:8080/mysite/B.
Then servlet B does its work and essentially invokes:
ctx.getRequestDispatcher("/C.jsp").forward(request, response);
then C.jsp sends back the response using data from the session.
Is this right?
(btw, you know your app'ss requirements better than I, but storing all
data in the session isn't the only scope available. It's likely that a
lot of response data needn't survive past the current request. In that
case, setting request attributes would be better -- less memory needed,
less likely to pick up data that's inappropriate for the current
request).
Yup thats correct.I will explore this option of moving attributes to
request.Thanks.
Now with my existing setup if I directly give url like
http://localhost:8080/mysite/C.jsp I go directly to C Jsp which I
should not because its not suppose to be accessed directly.
Right. Put C.jsp in WEB-INF, get a request dispatcher for
"/WEB-INF/C.jsp", forward to that and go home.
Yup got it.I think this should resolve my issue.
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