Configuring the Home Page of a Web Project

Table of contents

Article body

The problem: here is the overall structure of a simple project:

I wanted visiting the project, for example at http:localhost:8080, to go directly to index.jsp under WEB-INF rather than another default JSP.

I searched online for a long time. Most answers involved Tomcat’s XML configuration, welcome-file-list, or combining it with url-pattern, but none worked. Eventually, I stumbled on an approach that essentially makes another request. In index.jsp under WebContent, use the following:

Configure the page to refresh immediately, using a URL mapped by the backend controller. This comes close to navigating directly, although sometimes the JSP that sends the request is still briefly visible. I ultimately used this approach because I could not find another solution.

You might ask: why not configure url_pattern to intercept *.jsp, so the first request can enter the controller directly?

I tried this too. The request was intercepted, but its URL became WEB-INF/Page/index.jsp. According to the explanations I found online, Tomcat looks for index.jsp when loading the home page, or loads the configured index.jsp if welcome-file is set. So I expected it to access index.jsp under WebContent rather than WEB-INF. I do not understand why this happened; if you know, please explain in a comment.

P.S. Another approach is to intercept HTML pages and use FreeMarker. Since this project uses JSP, I will not explore that here.

Further issues:

1. During troubleshooting, I also encountered a “could not wired” problem. Based on my experience, I assumed a package had not been scanned, but all the packages were covered. I later found that web.xml was missing the contextListener configuration. I still do not fully understand the underlying reason. Thanks to this blogger for sharing.

2. After configuring everything, accessing the correct path still did not enter the controller. Scanning had not been enabled in Springmvc.xml, even though I had configured scanning for all packages in Spring. For the distinction, see this blogger’s explanation; it makes the difference clear.

I had not paid much attention to this before, and debugging the resulting errors was frustrating. My takeaway: Spring MVC manages controllers, so let it scan the controller packages. Spring manages services and transactions, so let it scan those packages. Each should handle its own responsibilities.

3. I also encountered a static resource configuration issue. Access to static resources is generally configured through mvc:resources, although mvc:default-servlet-handler/ can also be used. The latter leaves identification and handling to Spring MVC itself, which can sometimes cause errors, so I do not recommend it.

4. The XML file also reported that a wildcard match was available, but no declaration could be found for the element ‘context:component-scan’. Thanks to this blogger for sharing.

Trying this exposed how much I still did not understand. It was quite a wake-up call.

Update: 2019-3-21

A correction: some of the analysis above was wrong. I had configured the DispatcherServlet url-pattern as *.jsp or *.do, which does not fit the RESTful style now commonly used. I changed url-pattern to / to intercept all requests, and configured static resource access in sprngmvc.xml. With @requestmapping(value = ”/”) on the controller, I could handle the default index request and use ModelAndView to return the web-inf/index page. As for the URL changing, I have forgotten why I wrote it that way at the time; I was probably confused. I recommend mapping all requests with /, which makes RESTful routing easier to implement.