ModelDriven



ModelDriven

为什么user对象会在ValueStack中呢？它是什么时候被压入ValueStack的呢？答案是：ModelDrivenInterceptor，ModelDrivenInterceptor是缺省的拦截器链的一部分，当一个请求经过ModelDrivenInterceptor的时候，在这个拦截器中，会判断当前要调用的Action对象是否实现了ModelDriven接口，如果实现了这个接口，则调用getModel()方法，并把返回值（本例是返回user对象）压入ValueStack。

请看ModelDrivenInterceptor的代码：

public class ModelDrivenInterceptor extendsAbstractInterceptor {

 

   protected boolean refreshModelBeforeResult = false;

 

   public void setRefreshModelBeforeResult(boolean val) {

       this.refreshModelBeforeResult = val;

    }

 

   @Override

   public String intercept(ActionInvocation invocation) throws Exception {

       Object action = invocation.getAction();

 

       if (action instanceof ModelDriven) {

           ModelDriven modelDriven = (ModelDriven) action;

           ValueStack stack = invocation.getStack();

           Object model = modelDriven.getModel();

           if (model !=  null) {

              stack.push(model);

           }

           if (refreshModelBeforeResult) {

                invocation.addPreResultListener(newRefreshModelBeforeResult(modelDriven, model));

           }

       }

       return invocation.invoke();

    }

 

 

 

 

 

从ModelDrivenInterceptor中，即可以看到model对象被压入ValueStack中！