Spring UrlFilenameViewController Example
Hope you guys have enjoyed previous article, MultiActionController Example. Now, let’s move on to UrlFilenameViewController. It transforms the virtual path of a URL into a view name and returns the view, that’s it. It is useful when you don’t need any logical operation on request and simply wants to redirect to some resource. For example, each site has ‘Contact Us’, ‘About Us’ pages. To map those pages UrlFilenameViewController is a good choice. Let’s see the example.
Initially index.jsp is viewed to user,
index.jsp
<html> <head> </head> <body> <h3> Spring Demo </h3> <h4>1) <a href="About_Us.do">About Us</a></h4> <h4>2) <a href="Contact_Us.do">Contact Us</a></h4> </body> </html>
When submit button is pressed or hyperlink is clicked, flow will continue to WEB.XML from index.jsp
WEB.XML
<web-app> <!-- Below is Spring DispatcherServlet that is configured with FrontControllerServlet-servlet.xml --> <servlet> <servlet-name>FrontControllerServlet</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>FrontControllerServlet</servlet-name> <url-pattern>*.do</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.do</welcome-file> </welcome-file-list> </web-app>
WEB.XML instructs that, ‘*.do’ URLs are served by FrontControllerServlet. FrontControllerServlet is internally instantiated with the configuration file FrontControllerServlet-servlet.xml. (Remember Spring naming convention for DispatcherServlet configuration XML is ‘<DispatcherServlet name>-servlet.xml’)
FrontControllerServlet-servlet.xml
<beans> <!-- TO MAP URL TO PROPER CONTROLLER, 'SimpleUrlHandlerMapping' IS USED AS BELOW. ( Controller can be MultiAction/SimpleForm/UrlFilenameView etc.) --> <bean id="urlHandler"> <property name="mappings"> <map> <entry key="/index.do" value="urlFilenameViewController"/> <entry key="/About_Us.do" value="urlFilenameViewController"/> <entry key="/Contact_Us.do" value="urlFilenameViewController"/> </map> </property> </bean> <!-- BELOW, we instruct to change suffix to '.jsp' for any incoming request. In our case, '*.do' will be changed to '*.jsp'. e.g. index.do -> index.jsp About_Us.do -> About_Us.jsp Contact_Us.do -> Contact_Us.jsp --> <bean id="urlFilenameViewController"> <property name="suffix" value=".jsp" /> </bean> </beans>
Inside FrontControllerServlet, request is given to ‘SimpleUrlHandlerMapping bean’ initially.
There request is routed to proper controller bean. In our case, ‘*.do’ are routed to UrlFilenameViewController bean.
Now, UrlFilenameViewController simply replaces extension from ‘.do’ to ‘.jsp’.
E.g. For index.do, it returns index.jsp to user. No need of any business logic to process request.
(‘UrlFilenameViewController’ has also one more property, named as ‘prefix’. Find out how it works. It’s simple)
About_Us.jsp
<html> <head> </head> <body> <a href="index.do">HOME</a> <h2>About Us</h2> <h3>aaaaaaaaaaaaaaaaa. </h3> </body> </html>
Contact_Us.jsp
<html> <head> </head> <body> <a href="index.do">HOME</a> <h2>Contact Us</h2> <h3>Address: Satelite Road, Ahemedabad, India.</h3> <h3>Phone: 00-00000000</h3> </body> </html>
Download full source code here.
