Understanding Struts Controller
In this section I will describe you the Controller part
of the Struts Framework. I will show you how to configure the struts-config.xml
file to map the request to some destination servlet or jsp file.
The class org.apache.struts.action.ActionServlet
is the heart of the Struts Framework. It is the Controller part of the Struts
Framework. ActionServlet is configured as Servlet in the web.xml file
as shown in the following code snippets.
<!-- Standard Action Servlet Configuration (with debugging) -->
<servlet>
<servlet-name>action</servlet-name>
<servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
<init-param>
<param-name>config</param-name>
<param-value>/WEB-INF/struts-config.xml</param-value>
</init-param>
<init-param>
<param-name>debug</param-name>
<param-value>2</param-value>
</init-param>
<init-param>
<param-name>detail</param-name>
<param-value>2</param-value>
</init-param>
<load-on-startup>2</load-on-startup>
</servlet> |
This servlet is responsible for handing all the request
for the Struts Framework, user can map the specific pattern of request to the
ActionServlet. <servlet-mapping> tag in the web.xml file
specifies the url pattern to be handled by the servlet. By default it is *.do,
but it can be changed to anything. Following code form the web.xml file
shows the mapping.
<!-- Standard Action Servlet Mapping -->
<servlet-mapping>
<servlet-name>action</servlet-name>
<url-pattern>*.do</url-pattern>
</servlet-mapping> |
The above mapping maps all the requests ending with .do
to the ActionServlet. ActionServlet uses the configuration defined in struts-config.xml
file to decide the destination of the request. Action Mapping Definitions
(described below) is used to map any action. For this lesson we will create
Welcome.jsp file and map the "Welcome.do" request to this page.
Welcome.jsp
|
<%@ taglib uri="/tags/struts-bean" prefix="bean" %>
<%@ taglib uri="/tags/struts-html" prefix="html" %>
<html:html locale="true">
<head>
<title><bean:message key="welcome.title"/></title>
<html:base/>
</head>
<body bgcolor="white">
<h3><bean:message key="welcome.heading"/></h3>
<p><bean:message key="welcome.message"/></p>
</body>
</html:html>
|
Forwarding the Welcome.do request to Welcome.jsp
The "Action Mapping Definitions" is the most important part in the struts-config.xml.
This section takes a form defined in the "Form Bean Definitions"
section and maps it to an action class.
Following code under the <action-mappings> tag
is used to forward the request to the Welcome.jsp.
|
<action path="/Welcome"
forward="/pages/Welcome.jsp"/>
|
To call this Welcome.jsp file we will use the following code.
|
<html:link page="/Welcome.do">First Request to the controller</html:link>
|
Once the use clicks on on First Request to the controller
link on the index page, request (for Welcome.do) is sent to the
Controller and the controller forwards the request to Welcome.jsp. The
content of Welcome.jsp is displayed to the user.
|
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Current Comments
107 comments so far (post your own) View All Comments Latest 10 Comments:Hi,
I tired to do the same things as told. But i am not getting the link wiht the html:link tag.
What can i do?
Posted by amul on Monday, 04.21.08 @ 17:19pm | #57407
hi, I need to learn struts.Please send me
struts materials to my Email.I am trying to
run the struts login example but it showing
Error:Servlet action is not available.What is wrong
in my example.
Posted by vinay kumar on Friday, 04.4.08 @ 12:00pm | #55293
Hello EveryOne,
I wish If any body can hepm me out. I am developing a web site there I need to generate some reports which can be printed if needed. can anybody suggest me how that can be achieved.
I am using Oracle 10g as my backend database.
Posted by subrata on Thursday, 03.27.08 @ 12:12pm | #54471
Dear sir,
I am undergoing a training in struts,please send the struts material to my mail id.
Thanks & Regards
Posted by Shinu on Wednesday, 03.26.08 @ 16:05pm | #54392
RoseIndia is an Excellent site for Learning and .
Posted by venu on Wednesday, 03.26.08 @ 15:48pm | #54391
Hi this is Nagendra,i want a small program to store the name in to database by using struts.
Posted by Nagendrakumar.M on Monday, 03.24.08 @ 17:08pm | #54153
Hi,goodmorning.....
Iam Neelima.
This is very site,just 2days back only i know abt this site...it's very nice
But i want a simple struts example program.
Suppose i want a simple login page,so plz tell me that simple program code...
Thank's 4 giving this oppertinuty......
Posted by Neelima on Tuesday, 02.26.08 @ 12:43pm | #50112
Give a simple and small exmple which help 2 understood problem of struts
Posted by anoop on Thursday, 02.21.08 @ 17:53pm | #49322
I like very much this site "roseindia.net". Because i learned servlets and Jsp form this site. Now iam learning struts..... but i face one problem, every time iam comming to net and lerning. so is there any way to provide pdf file or any other formate
Posted by srinivas on Wednesday, 02.20.08 @ 17:53pm | #49217
Please give information abt what is debug=2 and details=2 and load-on-startup=2..
Your tutorials are too good...
thank you
Posted by Rajesh.K.T on Thursday, 02.14.08 @ 12:50pm | #48241