I have a simple web application running in Tomcat. There is a servlet which is forwarding the request and response to a jsp page which in turn prints something to the browser.
Now I have an aspect which captures the response. In this case a HttpServletResponse. Now what I want to do is that I want to capture the reponse and add some content in it to be displayed in the browser through JSP page.
I dont want to add the content in the jsp page rather I want to add some content without changing my jsp or servlet, using runtime weaving functionality of aspectJ.
I have not been able to figure out any solution yet.Please help me with this.Thanks.
We don't do that with the response. Request object is a better candidate for that. You must understand that JSP is a server-side technology, therefore your request used to be alive in the JSP page.
Moreover, I would suggest you to look at Servlet Filters, those are meant for this kinda scenarios.
Related
I have an iframe inside a jsp which is for processing payment using a third party payment provider.
When I get the response from payment provider, I use another jsp file just for breaking out of iframe (using javascript, as I could not find anything to do this in jsp, and probably there is no such way to do it in jsp AFAIK).
Now, the problem for me is the error scenario. When I receive some error from the payment provider, I want to display that on top of the page where I am redirecting to after breaking from iframe.
We use flash attributes for dispalying the error messages while doing redirect from spring mvc using redirect:.
But I am not sure how to do that when using a browser redirect.
One solution (Post/Redirect/Get pattern) I could think of is to append the error respone in the url which I am using in the redirect from breaking out of iframe.
But this would require changes to our jstl tag files and that will be different from the design of our existing code.
Can anyone point me to some better solution for this?
I ended up using session variable.
So just added a session variable in controller, and before the view was passed on from the last controller, copied the session variable into the redirect flash attributes and then it worked. I know this may not sound good enough, but that's how I had to make it work.
I have to create a little webshop for a school-project, but entered in to a problem during the process by updating/refreshing the Servlets.
Description:
I created an index.html file which includes two servlets via iframes, the left side for Navigation-Servlet and on the right the Controller-Servlet does something to show a welcome page (or shows off the categories etc.) - works all fine.
But now I have to implement a login with an small administration.
By clicking in the navigation on Administration, it leads to another Servlet called Administration-Servlet, in the right iframe (actually not over the Controller-Servlet).
There comes up a login mask, where the user put in his username and password. If the login was correct, it leads then to the administration content (not finished by now).
The upcoming problem is now that I somehow have to update/refresh the Navigation iframe too, when the login was successful because there must be the Logout-Button and some entries have to be hidden.
By which "technique" or pattern I can solve this problem? Maybe a little code example would be helpful. :)
Best greets.
Instead of using Iframes to put together the different parts of your site, use dynamic include in your servlets. This will allow you to build the response page server side and therefore dynamically change what is included in a page. When you log in you send the authentication request to the servlet which will then dynamically construct the new response from multiple JSP files.
<jsp:include page="..." />
Another solution is to use a scripting language like Apache Velocity Template scripts to build your responses dynamically. Allowing you to include or exclude information depending on parameters or session context.
In my spring mvc application,I am facing a problem of page reloading on every request.Is there any way to restrict that.To be more specific,When I return the name of index.jsp page from controller it will obviously reload the page.How Can I restrict that thing in the index.jsp page.Suppose some part of the page is required to interact with Database and it should be shown on the same index.jsp page as well.How I can achieve this requirement without reloading the index.jsp page completely.Could you please provide me some example for that.
You can use Filter for that. I am not providing any code here, just try to explain the concept.
Filters have a wide array of uses; the Servlet 2.3 specification suggests the following uses:
authentication filters
logging and auditing filters
image conversion filters
data compression filters
encryption filters
tokenizing filters
filters that trigger resource access events
XSL/T filters that transform XML content
MIME-type chain filters
Use a Filter when you want to filter and/or modify requests based on specific conditions.
Use a Servlet when you want to control, preprocess and/or postprocess requests.
Filter are best suited for authorization, because it can be configured to run for all pages of a site. So you only need one filter to protect all your pages.
Useful Links:
filter tutorial
filter in detail
referred answer
Oracle tutorial on Filter
sorry if i missunderstanding you!
i don't know what do you want to do but i can imagine the following solution.
first direct call to jsp should check a session value, if not exists, redirect from jsp to servlet, in the servlet do what you wand and finally put this session value, and redirect back to jsp.
a good concept depends on what you want to do exactly. You can manage this issue using a PhaseListener or a Filter. but if you just want to manage this one redirect, then no need of Filter or PhaseListener
I would like to read jsp page from my application and save it to a file - it's output, not the code itself. Plus, my application has basic authentication (username+password).
If it was a Servlet, I could just access it's doGet method.
One solution I've found is this - Open URL connection, provide authentication details and read the stream.
I'm wondering if there's another option, maybe accessing the generated Servlet in the web container and then using reflection to call the class doGet.
You can precompile the JSP and then call the servlet (you don't have to use reflection even).
If you try to call the JSP's servlet without precompiling then it might not exit yet (because usually the server only compiles the JSP after it was called for the first time).
To precompile the JSP, check your web server documentation.
Personally I think you're better of using URL connection. Precompiling JSPs is not portable (as in you need to do it in a different way for each web server).
Edit
You can also use RequestDispatcher.include() method with a wrapped response object as described in this answer.
I wrote custom servlet in Liferay and want to know which user page calls it and know other parameters like theme. But the request's attributes and session fields are all nulls.
How to make custom servlet to receive request as if portlet does?
Thanks
P.S. I don't want to use this solution https://www.everit.biz/web/guest/blog/-/blogs/getting-current-liferay-user-in-a-standalone-webapp?_33_redirect=/web/guest/blog
which reads cookies manually. I want to do such as Liferay does, i.e. by using it's API. Is it possible?
Update 1.
I have a portlet and a servlet in one WAR. I can know who am I (logged in user) from within portlet JSP like this:
HttpServletRequest request = (HttpServletRequest)pageContext.getRequest();
ThemeDisplay themeDisplay = (ThemeDisplay)request.getAttribute(WebKeys.THEME_DISPLAY);
themeDisplay.getUser()
Now I want to do the same from a servlet. Is it possible?
I am working in eclips which deploys automatically.
You either have to mimic what Liferay does in the portlet request handling (not recommended) or, alternatively, put your servlet code into a portlet - this can be the "resource handling" of a portlet - here you get full access to the http request and can do everything yourself with regards to data types transmitted in the stream.
I'd rather recommend this as it will be significantly easier to upgrade. Portlet Resource Handler are very similar to servlets from a logical point of view. There might be other (more advisable) options, but this is what comes to my mind for this type of problem.