使用ModelDriven action

Model-Driven vs. Field-Driven
  two types of Actions possible:
  1. Model-driven
      Action has methods returning your model classes (myAction.getUser())
      Fields in the view are fields of your model
      Views refer directly to your model (property=‘user.name’)
      Excellent because it allows model reuse

  2. Field-driven
    Action has fields of its own, which are fields in the view
    execute() collates fields and interacts with the model
    Views refer to action fields (property=‘daysTillNextBirthday’)
    Useful where form is not parallel to model

 As we can see in our Action, the two can be mixed


ModelDriven Interface
XWork / WebWork also supports modeldriven Actions more directly
The ModelDriven Interface has one method:
        public Object getModel()
Properties of the model will be directly available, i.e. “name” instead of “user.name”
Applies to UI tags, form field names, etc.


步骤：
（1）Action implements ModelDriven接口
（2）实现getModel()方法：
    public Object getModel() {
        return user;
    }
（3）将jsp页面上user.name 改成name
（4）在xwork.xml中，
<pancakmaegsep ancaem=e"=/"eexx22""> extends="webwork-default"
  <action name="main" class="com.opensymphony.xwork.ActionSupport">
    <result>/model/form.jsp</result>
</action>

<action name="HelloWorld" class="example.ex2.HelloWorldAction">
    <interceptor-ref name="model-driven"/>
    <interceptor-ref name="defaultStack"/>
    <result>/model/success.jsp</result>
    <result name="input">/model/form.jsp</result>
</action>
</package>