struts 2应用程序无需JSP即可呈现结果。 这怎么可能？

Question

I am following the tutorial on struts 2 at http://www.simplecodestuffs.com/integrating-jquery-datatable-with-struts2-using-ajax-to-implement-gridview/

I understood the core concepts like using POJO action classes struts.xml configurations etc. But whats troubling me is in this tutorial, there is a jsp result mentioned in struts.xml called " grid.jsp". But this page is not at all present in the application and it still works.

How can this happen? does struts 2 generate some jsp templates? Please check the attached screenshot. It has the project structure and struts.xml.

I have tried various books and tutorials and google searches but this topic has never been discussed. Please help. I would like to learn the flow from when the request reaches the action class.

These kind of examples are also present in struts2 showcase.

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
"-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
    <package name="default" extends="json-default">
        <action name="dataTablesAction" class="com.action.GridViewAction">
            <result type="json">grid.jsp</result>
        </action>
    </package>

</struts>

Answer 1

@zapl already answered you, I'll delete this answer if he will post his comments as an answer.

When you write

 <result type="json">grid.jsp</result>

it will be translated to

 <result name="success" type="json"></result>

"success" will be added because of Intelligent Default ("success" is taken if no name specified) and the entire Action will be serialized into JSON, because that's how the JSON plugin works . You can specify a root object, but you can't specify a JSP, because JSP != JSON, and because raw text (like a jsp name) is not expected to be found there in the config. Your grid.jsp will be simply ignored and cropped at all (not tested, but I'm pretty sure).