接著學(xué)習(xí)struts的相關(guān)組件
Action Mapping
 每一個<action>元素都與類org.apache.struts.action.ActionMapping的一個實(shí)例對應(yīng)，包括name,path,forward。

An ActionMapping represents the information that the controller, RequestProcessor, knows about the mapping of a particular request to an instance of a particular Action class. The ActionMapping instance used to select a particular Action is passed on to that Action, thereby providing access to any custom configuration information included with the ActionMapping object.

下面利用Action Mapping的相關(guān)方法 測試得到Action Mapping的屬性值
在AddStudentAction增加以下代碼

重新部署web應(yīng)用 觀察控制臺輸出

其與struts-config.xml中的代碼對應(yīng)
注意：外部不可以使用set方法不能設(shè)置其屬性  因?yàn)榕渲梦募呀?jīng)被frozen！

ActionForward（導(dǎo)航器）
       ActionForward對象是配置對象。這些配置對象擁有獨(dú)一無二的標(biāo)識以允許它們按照name屬性等來檢索。ActionForward對象封裝了向前進(jìn)的URL路徑且被請求處理器用于識別目標(biāo)視覺。
       name：邏輯名稱
       path：頁面或者模塊訪問路徑

An ActionForward represents a destination to which the controller, RequestProcessor, might be directed to perform a RequestDispatcher.forward or HttpServletResponse.sendRedirect to, as a result of processing activities of an Action class. Instances of this class may be created dynamically as necessary, or configured in association with an ActionMapping instance for named lookup of potentially multiple destinations for a particular mapping instance.

An ActionForward has the following minimal set of properties. Additional properties can be provided as needed by subclassses.

• contextRelative - Should the path value be interpreted as context-relative (instead of module-relative, if it starts with a '/' character? [false]
• name - Logical name by which this instance may be looked up in relationship to a particular ActionMapping.
• path - Module-relative or context-relative URI to which control should be forwarded, or an absolute or relative URI to which control should be redirected.
• redirect - Set to true if the controller servlet should call HttpServletResponse.sendRedirect() on the associated path; otherwise false. [false]

redirec:
    fale,no    ————      RequestDispatcher.forword  路徑相對當(dāng)前應(yīng)用
    true,yes  ————      HttpServletResponse.sendRedirec.path 寫絕對路徑

ActionForm
   工作原理
處理ActionForm的一般步驟：
   (1)檢查Action的映射，確定Action中已經(jīng)配置了對ActionForm的映射。
   (2)根據(jù)name屬性，查找form bean的配置信息。
   (3)檢查Action的form bean的使用問題，確定在此范圍下（request，session），是否已經(jīng)有此form bean的實(shí)例。
   (4)假如當(dāng)前范圍下，已經(jīng)存在了此form bean的實(shí)例，而是對當(dāng)前請求來說，是同一種類型的話，那么就重用。
   (5)否則，就重新構(gòu)建一個form bean的實(shí)例（調(diào)用構(gòu)造方法），并且保存在一定作用范圍。
   (6) form bean的reset()方法被調(diào)用
   (7)調(diào)用對應(yīng)的setter方法，對狀態(tài)屬性賦值
   (8)如果validate的屬性設(shè)置為true，那么就調(diào)用form 備案的validate方法。
   (9)如果validate方法沒有返回任何錯誤，控制器將ActionForm作為參數(shù)，傳給Action實(shí)例的execute方法執(zhí)行。
注意：直接從ActionForm類繼承的reset和validate方法，并不能實(shí)現(xiàn)什么處理功能，所以有必要自己重新覆蓋。



總覺得學(xué)習(xí)組件有點(diǎn)無聊，也許明天開始學(xué)習(xí)另外一個實(shí)例。其他組件過段時間再學(xué)習(xí)了！