DispatchAction, LookupDispatchAction, MappingDispatchAction

1) DispatchAction就是在struts-config中用parameter參數配置一個表單字段名,這個字段的值就是最終替代execute被調用的方法. 例如parameter="method"而request.getParameter("method")="save"，其中"save"就是MethodName。struts的請求將根據parameter被分發到"save"或者"edit"或者什么。但是有一點，save()或者edit()等方法的聲明和execute必須一模一樣。同時：刪除以前的execute(----)方法，如:
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-------
public class UserAction extends DispatchAction

{

??? public ActionForward addUser (ActionMapping mapping,ActionForm form,

??????????? HttpServletRequest request,HttpServletResponse response) throws Exception

??? {

???????????? // 增加用戶業務的邏輯

??????????? return mapping.findForward(Constant. FORWARD_ADD );

??? }

???

??? public ActionForward delUser(ActionMapping mapping,ActionForm form,

??????????? HttpServletRequest request,HttpServletResponse response) throws Exception

??? {

???????????? // 刪除用戶業務的邏輯

??????????? return mapping.findForward(Constant. FORWARD_SUCCESS );

??? }

??? public ActionForward updateUser(ActionMapping mapping,ActionForm form,

??????????? HttpServletRequest request,HttpServletResponse response) throws Exception

??? {

???????????? // 更新用戶業務的邏輯

??????????? return mapping.findForward(Constant. FORWARD_SUCCESS );

??? }

}

?

2) LookupDispatchAction繼承DispatchAction, 用于對同一個頁面上的多個submit按鈕進行不同的響應。其原理是，首先用MessageResource將按鈕的文本和ResKey相關聯，例如button.save=save；然后再復寫getKeyMethodMap(), 將ResKey和MethodName對應起來, 例如map.put("button.save", "save"); 其配置方法和DispatchAction是一樣的,? parameter屬性為：method 如：
<html:submit property="method">
<bean:message key="button.save"/>
</html:submit>
<html:submit property="method">
<bean:message key="button.delete"/>
</html:submit>
注意：此Action一定要有對應的FormBean， 就是說一定要有name屬性， 同時要刪除此類的execute(-----)方法
資源文件如:
button.save=save
button.delete=delete

3) MappingDispatchAction是1.2新加的, 也繼承自DispatchAction. 它實現的功能和上面兩個區別較大, 是通過struts-config.xml將多個action-mapping映射到同一個Action類的不同方法上, 典型的配置就是:
<action-mappings>
<action path="/saveUser" type="logic.UserAction" parameter="save"></action>
<action path="/editUser" type="logic.UserAction" parameter="edit"></action>
</action-mappings>
然后UserAction繼承MappingDispatchAction，其中有：
public ActionForward save(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
public ActionForward edit(ActionMapping mapping, ActionForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
等方法