ActionContext 中的数据详解

部分参考《Struts2技术内幕》

ActionContext 作为ValueStack的上下文环境  <|——ServletActionContext
    |——context：OgnlContext implements Map ActionContext.getContextMap(),ognl上下文
           |——_root：CompountRoot extends ArrayList ：ognl的根
           |  内容：( HashMap：ActionContext.getValueStack().set(key,vlaue)用到的HashMap
           |        当前Action实例
           |        DefaultTextProvider：)
           |——classResolver：CompoundRootAccessor指定处理class loading的处理类
           |——converter：OgnlTypeConverterWrapper指定处理类型转换的处理类
           |——memberAccess：SecurityMemberAccess指定处理属性访问策略的处理方式
           |——_value：HashMap ：使用一个Map来维护ognl的上下文
===========ActionContext.context._value中的数据========================
Web原生对象：
Com.opensymphony.xwork2.dispatcher.HttpServletRequest——StrutsRequestWrapper
Com.opensymphony.xwork2.dispatcher.HttpServletResponse——ResponseFacade implements HttpServletResponse 
Com.opensymphony.xwork2.dispatcher.ServletContext——ApplicationContextFacade

XWork封装对象：
Com.opensymphony.xwork2.ActionContext.application——ApplicationMap<K,V>
                                                                                                <——ActionContext.getApplication()
Com.opensymphony.xwork2.ActionContext.session——SessionMap<K,V>
                                                                                                <——ActionContext.getSession()
Com.opensymphony.xwork2.ActionContext.parameters——TreeMap<K,V>  <——ActionContext.getParameters() 返回 HttpServletRequest(get|post,String[],有重复参数名也不覆盖)参数的map
Com.opensymphony.xwork2.util.ValueStack.ValueStack——OgnlValueStack                                                                                                  <——ActionContext.getValueStack()

application——ApplicationMap<K,V>
session——SessionMap<K,V>
parameters——HashMap：
request——RequestMap
attri——AttributeMap
action——当前Action类

自定义key——自定义值：使用ActionContext.put(key,value)，ActionContext.get(key)

Com.opensymphony.xwork2.ActionContext.name——fmCS：Action标签的name属性
                                                                                                <—— ActionContext.getName()
Com.opensymphony.xwork2.ActionContext.container——ContainerImpl：struts2的容器
                                                                                                <—— ActionContext.getContainer()
Com.opensymphony.xwork2.ActionContext.actionInvocation——DefaultActionInvocation
                                                                                                <——ActionContext.getActionInvocation()
Com.opensymphony.xwork2.ActionContext.conversionErrors——HashMap 
                                                                                                   <——ActionContext.getConversionErrors()
Com.opensymphony.xwork2.ActionContext.local——Lcale         <——ActionContext.getLocale()
Struts2.actionMapping——ActionMapping

Xwork.NullHandler.createNullObjects——boolean
Xwork.MethodAccessor.denyMethodExecution——Boolean
Report.conversion.errors——Boolean
Current.property.path——
Last.property.accessed——
Last.bean.accessed——
======================================================================
OgnlValueStack：对ognl中的root对象的扩展，具有栈结构
      |——context：OgnlContext，差不多就是ActionContext
      |——root：CompoundRoot：对valuestack的操作用到的是这里的数据
ValueStack中的[n]表示除栈结构中前N个元素之后构成的元素集合。通过CompoundRoot的cutStack()实现。

使用装饰者模式
StrutsRequestWrapper——|>HttpServletRequestWrapper——|>ServletRequestWrapper      
|——request：RequestFacade
      |——request：Request
                      |——attributes：HashMap<K,V>

StrutsRequestWrapper有子类HttpServletRequestWrapper，实现HttpServletRequest接口

使用适配器模式
ApplicationMap
  |——context：ApplicationContextFacade
  |——entries：HashSet<Set>
public class ApplicationMap extends AbstractMap implements Serializable
Struts2 API解释：A simple implementation of the Map interface to handle a collection of attributes and init parameters in a ServletContext object. The entrySet() method enumerates over all servlet context attributes and init parameters and returns a collection of both. Note, this will occur lazily - only when the entry set is asked for

SessionMap
      |——entries
      |——request：StrtusRequestWrapper
      |——session：StandardSessionFacade
public class SessionMap extends AbstractMap implements Serializable
Struts2 API解释：A simple implementation of the Map interface to handle a collection of HTTP session attributes. The entrySet() method enumerates over all session attributes and creates a Set of entries. Note, this will occur lazily - only when the entry set is asked for.

RequestMap 
      |——entries
      |——request：StrutsRequestWrapper
public class RequestMap extends AbstractMap implements Serializable
Struts2 API解释：A simple implementation of the Map interface to handle a collection of request attributes.

AttributeMap
public class AttributeMap implements Map
Struts2 API解释：
A Map that holds 4 levels of scope.
The scopes are the ones known in the web world.:
Page scope
Request scope
Session scope
Application scope
A object is searched in the order above, starting from page and ending at application scope.

===================================================================
Struts2下的FreeMarker：
参考Struts2API类FreemarkerResult的createModel方法：
Build the instance of the ScopesHashModel, including JspTagLib support
Objects added to the model are 

//1）Application - servlet context attributes hash model 
atc.getApplication().put("fmApplication", "application 测试"); 
${Application.fmApplication}   

//2）Request - request attributes hash model 
ServletActionContext.getRequest().setAttribute("servletRequestFM", "原生Request 测试"); 
${Request.servletRequestFM} 

//3）Session - session attributes hash model 
atc.getSession().put("fmSession", "session 测试"); 
${Session.fmSession} 

//4）stack - the OgnLValueStack instance for direct access 
atc.put("fmActionContext", "actionContext 测试"); 
${stack.context.fmActionContext} 
atc.getValueStack().set("fm_set_ValueStack", "valueStack set  测试"); 
${stack.root[0].fm_set_ValueStack} 

//5）action - the action itself 
private String fmStr="action 域  FreeMarker 测试"; getter,setter 
${action.fmStr} 

//6）request - the HttpServletRequst object for direct access 
//7）response - the HttpServletResponse object for direct access 
//8）ognl - the instance of the OgnlTool 
//9）JspTaglibs - jsp tag lib factory model 
//10）struts - instance of the StrutsUtil class 
//11）exception - optional : the JSP or Servlet exception as per the servlet spec (for JSP Exception pages)