The middle-tier component of the Java EE architecture consists of an application server often fronted by a web server. These servers serve up web content and execute servlets and JSP pages in response to incoming client requests. Figure 10-1 illustrates how client request flow through a stand-alone application server such as Tomcat.
Filters can be used to do the following:
- Inspect the request header and data before it reaches the resouce
- Inspect the response header and data after it has been sent by the resource
- Provide a Modified version of the request to the resource being processed by the container.
- Access and modify the response from the resource before returning it .
- Stop a request from reaching a resource altogether.
Filter life cycle is like servlet. Filter definition and filter mapping.
Matching URL patterns:
/* Everything that is served by this web application, including static pages, servlets, and jsp pages.
/servlet/* All Servlets under the /servlet path
/jsp/*.jsp
/dept/accounting/*
Filter chain:
javax.servlet.Filter
javax.servlet.FilterChain
All filters are chainable.