Question

Struts中的LookupDispatchAction类的具体用法

Answer 1

简单地讲，它具备这样一个功能：可能根据被提交表单中你所点击的提交按钮名称，自动分发对应的处理方法，比如可轿旦以通过点击一个名称为add的提交按钮，触发一个Action的add方法，但你点击名为remove的提交宏帆禅按钮，又可以触发同一个Action的remove方法。个人认为使用价值不高，完全可以通过JS和DispatchAction实现类似功能。

下面是官方的使用示例：
public abstract class LookupDispatchAction
extends DispatchAction

An abstract Action that dispatches to the subclass mapped execute method. This is useful in cases where an HTML form has multiple submit buttons with the same name. The button name is specified by the parameter property of the corresponding ActionMapping. To configure the use of this action in your struts-config.xml file, create an entry like this:

<action path="/test"
type="org.example.MyAction"
name="MyForm"
scope="request"
input="/test.jsp"
parameter="method"/>

which will use the value of the request parameter named "method" to locate the corresponding key in ApplicationResources. For example, you might have the following ApplicationResources.properties:

button.add=Add Record
button.delete=Delete Record

And your JSP would have the following format for submit buttons:

<html:form action="/test">
<蔽尘html:submit property="method">
<bean:message key="button.add"/>
</html:submit>
<html:submit property="method">
<bean:message key="button.delete"/>
</html:submit>
</html:form>

Your subclass must implement both getKeyMethodMap and the methods defined in the map. An example of such implementations are:

protected Map getKeyMethodMap() {
Map map = new HashMap();
map.put("button.add", "add");
map.put("button.delete", "delete");
return map;
}

public ActionForward add(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
// do add
return mapping.findForward("success");
}

public ActionForward delete(ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response)
throws IOException, ServletException {
// do delete
return mapping.findForward("success");
}

Notes - If duplicate values exist for the keys returned by
getKeys, only the first one found will be returned. If no corresponding key
is found then an exception will be thrown. You can override the
method unspecified to provide a custom handler. If the submit
was cancelled (a html:cancel button was pressed), the custom
handler cancelled will be used instead.