『』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