LookupDispatchAction使用示例

最新推荐文章于 2011-05-05 16:14:00 发布

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最新推荐文章于 2011-05-05 16:14:00 发布

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本文介绍Struts2框架中的LookupDispatchAction类，该类为抽象基类，用于实现带有多个相同名称提交按钮的HTML表单。通过配置struts-config.xml文件，使用请求参数定位对应的执行方法。

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LookupDispatchAction

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">
    <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.