Major Description
Provide an application page interceptor / listener facility into Click. The concept is to provide an extension point for code which can listener to key page events and also interrupt normal page processing flow.
Using this code which tends to be incorporated into Page superclasses can be refactored into listener classes which can be reused in applications. This approach supports Page design by composition, rather than through inheritance.
Page listeners could be used for:
- enforcing an application wide security polity, rather than using the Page#onSecurityCheck() method
- dependency injection, see CLK-581
- support page performance profiling and logging
The listener interface would be:
public interface PageInterceptor
{ boolean pageCreate(Class<? extends Page> pageClass, Context context); boolean postCreate(Page page); boolean preResponse(Page page); void postDestroy(Page page); }Application page interceptor classes would be defined in the click.xml configuration file. Applications could defined multiple interceptor which would be executed sequentially in the order in which there are defined. Lnterceptor could have a scope / lifecycle of request (where by new instances are created for each page request, and are threadsafe), or application (where by a single instance is created and used for all page requests). interceptor can also be configured to have properties which are set after creation. This scope rules equates to Spring prototype and singleton scopes.
An example configuration is provided below:
<page-interceptor classname="com.mycorp.listener.ProfilingInterceptor"/>
<page-interceptor classname="com.mycorp.listener.SecurityInterceptor" scope="application">
<property name="notAthenticatedPath" value="/login.htm"/>
<property name="notAuthorizedPath" value="/not-authorized.htm"/>
</page-interceptor >