Struts2拦截器defaultStack与paramsPrepareParamsStack

struts-default.xml中定义了一系列的拦截器和拦截器链

同时也定义了一个默认的拦截器defaultStack，一旦定义了默认的拦截器，

该拦截器就会对包中的所有的Action起作用，当然如果你的Action中显式地定义了拦截器，

默认拦截器就会失去作用，如果想不让他失去作用，

也必须显式地定义系统默认的拦截器。

  
    

   
      
   
     </
   
     interceptors
   
     >
   
     

 
   
     <
   
     default-interceptor-ref 
   
     name
   
     ="defaultStack"
   
     />
   
     

 
   
     <
   
     default-class-ref 
   
     class
   
     ="com.opensymphony.xwork2.ActionSupport"
   
      
   
     />
   
     
 
   
     </
   
     package
   
     >
  
    

“defaultStack”和“paramsPrepareParamsStack”拦截器栈都提供了拦截器大部分功能

只是拦截顺序不一样。一般情况下会使用前者，但是某些涉及参数传递和取值的问题

例如实现了ModelDriven接口的某些时候，使用后者，就不用自己再额外编写拦截器类了

defaultStack

  
    

   
      
   
     <
   
     interceptor-stack 
   
     name
   
     ="defaultStack"
   
     >
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="exception"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="alias"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="servletConfig"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="i18n"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="prepare"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="chain"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="debugging"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="scopedModelDriven"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="modelDriven"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="fileUpload"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="checkbox"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="multiselect"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="staticParams"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="actionMappingParams"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="params"
   
     >
   
     
 
   
     <
   
     param 
   
     name
   
     ="excludeParams"
   
     >
   
     dojo\..*,^struts\..*
   
     </
   
     param
   
     >
   
     
 
   
     </
   
     interceptor-ref
   
     >
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="conversionError"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="validation"
   
     >
   
     
 
   
     <
   
     param 
   
     name
   
     ="excludeMethods"
   
     >
   
     input,back,cancel,browse
   
     </
   
     param
   
     >
   
     
 
   
     </
   
     interceptor-ref
   
     >
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="workflow"
   
     >
   
     
 
   
     <
   
     param 
   
     name
   
     ="excludeMethods"
   
     >
   
     input,back,cancel,browse
   
     </
   
     param
   
     >
   
     
 
   
     </
   
     interceptor-ref
   
     >
   
     
 
   
     </
   
     interceptor-stack
   
     >
  
    

paramsPrepareParamsStack

  
    

   
      
   
     <
   
     interceptor-stack 
   
     name
   
     ="paramsPrepareParamsStack"
   
     >
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="exception"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="alias"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="i18n"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="checkbox"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="multiselect"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="params"
   
     >
   
     
 
   
     <
   
     param 
   
     name
   
     ="excludeParams"
   
     >
   
     dojo\..*,^struts\..*
   
     </
   
     param
   
     >
   
     
 
   
     </
   
     interceptor-ref
   
     >
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="servletConfig"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="prepare"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="chain"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="modelDriven"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="fileUpload"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="staticParams"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="actionMappingParams"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="params"
   
     >
   
     
 
   
     <
   
     param 
   
     name
   
     ="excludeParams"
   
     >
   
     dojo\..*,^struts\..*
   
     </
   
     param
   
     >
   
     
 
   
     </
   
     interceptor-ref
   
     >
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="conversionError"
   
     />
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="validation"
   
     >
   
     
 
   
     <
   
     param 
   
     name
   
     ="excludeMethods"
   
     >
   
     input,back,cancel,browse
   
     </
   
     param
   
     >
   
     
 
   
     </
   
     interceptor-ref
   
     >
   
     
 
   
     <
   
     interceptor-ref 
   
     name
   
     ="workflow"
   
     >
   
     
 
   
     <
   
     param 
   
     name
   
     ="excludeMethods"
   
     >
   
     input,back,cancel,browse
   
     </
   
     param
   
     >
   
     
 
   
     </
   
     interceptor-ref
   
     >
   
     
 
   
     </
   
     interceptor-stack
   
     >
  
    

defaultStack无法接收prepare()需要的数据，而应借助paramsPrepareParamsStack拦截器栈

使用prepare拦截器之前，应先调用params拦截器，prepare() 才能接收到表单数据

基于这个思路，可以通过各种手段将params拦截器放置在prepare拦截器之前即可

比如将defaultStack中的所有拦截器拷贝到struts.xml的我们自定义的myStack拦截器栈中

再按照paramsPrepareParamsStack拦截器栈中的params和prepare顺序修改二者位置即可