| BeanAction is an extension to the typical Struts Action class that enables
mappings to bean methods. This allows for a more typical Object Oriented
design where each object has behaviour as part of its definition. Instead of
writing separate Actions and Forms, BeanAction allows you to simply have a
Bean, which models both the state and the methods that operate on that state.
In addition to the simpler packaging, BeanAction also simplifies the
Struts progamming paradigm and reduces dependency on Struts. Using this
pattern could allow easier migration to newer frameworks like JSF. The
method signatures are greatly simplified to the following
public String myActionMethod() {
//..work
return "success";
}
The return parameter becomes simply the name of the forward (as defined in
the config file as usual). Form parameters, request, response, session,
attributes, and cookies are all accessed via the ActionContext class (see the
ActionContext javadocs for more). The forms that you map to a BaseAction
mapping must be a subclass of the BaseBean class. BaseBean continues to
simplify the validation and reset methods by removing the parameters from the
signature as was done with the above action method example. There are 3
ways to map a BeanAction in the struts configuration file. They are as
follows. URL Pattern This approach uses the end of the
action definition to determine which method to call on the Bean. For example
if you request the URL: http://localhost/jpetstore4/shop/viewOrder.do
Then the method called would be "viewOrder" (of the mapped bean as
specified by the name="" parameter in the mapping below). The mapping used
for this approach is as follows.
<action path="/shop/<b>viewOrder</b>" type="com.ibatis.struts.BeanAction"
name="orderBean" scope="session"
validate="false">
<forward name="success" path="/order/ViewOrder.jsp"/>
</action>
Method Parameter This approach uses the Struts action parameter
within the mapping to determine the method to call on the Bean. For example
the following action mapping would cause the "viewOrder" method to be called
on the bean ("orderBean"). The mapping used for this approach is as follows.
<action path="/shop/viewOrder" type="com.ibatis.struts.BeanAction"
<b>name="orderBean" parameter="viewOrder"</b> scope="session"
validate="false">
<forward name="success" path="/order/ViewOrder.jsp"/>
</action>
No Method call BeanAction will ignore any Struts action mappings
without beans associated to them (i.e. no name="" attribute in the mapping).
If you do want to associate a bean to the action mapping, but do not want a
method to be called, simply set the parameter to an asterisk ("*"). The
mapping used for this approach is as follows (no method will be called).
<action path="/shop/viewOrder" type="com.ibatis.struts.BeanAction"
<b>name="orderBean" parameter="*"</b> scope="session"
validate="false">
<forward name="success" path="/order/ViewOrder.jsp"/>
</action>
A WORK IN PROGRESS The BeanAction Struts extension is a
work in progress. While it demonstrates good patterns for application
development, the framework itself is very new and should not be considered
stable. Your comments and suggestions are welcome. Please visit http://www.ibatis.com for contact
information. Date: Mar 11, 2004 10:03:56 PM
author:
Clinton Begin
See Also: BaseBean
See Also: ActionContext |