Load dynamic .jsp page on pageload with specific servlet

Question

I would like to create a .jsp page that is to be loaded on pageload, but the content of the page is dynamically created by calling my local database.

My question is. When a user request the index.jsp page, how do i "say". Before displaying the index.jsp page call servletX to get content, and send this back to the index.jsp page?

I have mapping my jsp and servlet together as follows

<servlet>
    <servlet-name>intname</servlet-name>
    <servlet-class>ServletBooks</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>intname</servlet-name>
    <url-pattern>/index.jsp</url-pattern>
</servlet-mapping>

But dont know how i send the dispather, back to self? getServletContext().getRequestDispatcher(???).forward(request, response);

Edit. Okey so now the site works as follows. I request the index.jsp page, which is mapped in the web.xml to a servlet. But if i set the requestDispatcher to the index.jsp page, the whole site hangs. If i set it to another page like result1.jsp it works fine. Execpt it isint the index page displaying the content.

How do i say to the servlet, send output to initiator?

Rather than going from jsp -> servlet, i would map a servlet to that jsp's path, and use the servlet to include your jsp. — Zachary Craig, Feb 25 '15 at 10:55
Try something like this https://zack6849.com/uploads/N2VmYjA3Y2Y0.png and this https://zack6849.com/uploads/ZTZjMzlhNGU0.png — Zachary Craig, Feb 25 '15 at 11:18
Im not sure i follow, you ALWAYS need to call a index page before anything else can be called? And how do you in a servlet say "send the output back to initiator" instead of calling a new page like a result.jsp page. — Cristian Matthias Ambæk, Feb 25 '15 at 13:51

Alan Hay · Accepted Answer · 2016-04-26T07:49:00.427

2

But if i set the requestDispatcher to the index.jsp page, the whole site hangs. If i set it to another page like result1.jsp it works fine.

Yes, because it is obviously going into an infinite loop as index.jsp is mapped to the Servlet you are forwarding from.

You need to have a look at the ModelViewController pattern. Essentially you never allow direct access to JSP but route through a controller, in your case a simple Servlet which will load any data required for the view and then dispatch to the view for rendering.

<servlet>
    <servlet-name>intname</servlet-name>
    <servlet-class>ServletBooks</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>intname</servlet-name>
    <url-pattern>/loadBooks.do</url-pattern>
</servlet-mapping>

<!-- If you are on Tomcat set a Default page if root of webapp requested -->
<welcome-file-list>
    <welcome-file>loadBooks.do</welcome-file>
</welcome-file-list>

In your servlet load the data and now forward to index.jsp.

http://www.thejavageek.com/2013/08/11/mvc-architecture-with-servlets-and-jsp/

edited Apr 26 '16 at 07:49

answered Feb 25 '15 at 19:24

Alan Hay

20,941
2
47
97

So the /loadBooks.do is a servlet? Why does it have a [dot]do? – Cristian Matthias Ambæk Feb 26 '15 at 17:55
You can make it whatever you want but why .do? See: http://stackoverflow.com/questions/3597582/why-do-java-webapps-use-do-extension-where-did-it-come-from – Alan Hay Feb 26 '15 at 18:23
Im no JSP pro and i dont quite get it yet. What does loadBooks.do represent. Is it a servlet that passes the request and response objects to another servlet that then creates that page? Is it a fiction value that does not exist as a physical file? Something else? – Cristian Matthias Ambæk Feb 26 '15 at 18:40
Thanks for all the info i got it working following the example, after realising the url-pattern is just a fictitious value that act as a link between two things. – Cristian Matthias Ambæk Mar 01 '15 at 15:01

Load dynamic .jsp page on pageload with specific servlet

1 Answers1