INTERVIEW QUESTIONS J2EE STRUTS DETAILS

Question: What we will define in Struts-config.xml file. And explain their purpose?

Answer: In struts-config.xml we define Date Sources / Form Beans / Global Exceptions / Global Forwards / Action Mappings / Message Resources / Plug-ins

Example :

<!-- Date Sources -->
<data-sources>
<data-source autoCommit="false" description="First Database Config" driverClass=" org.gjt.mm.mysql.Driver" maxCount="4" minCount="2" password="admin" url="jdbc: mysql://localhost/ARTICLEDB" user="admin">
</<data-sources>
<!-- Form Beans -->
<form-beans>
<form-bean name="registrationForm" type="com.aaa.merchant.wsp.ActionForms.RegistrationForm">
</form-bean>

<!-- Global Exceptions -->
<global-exceptions>
<exception key="some.key" type="java.io.IOException" handler="com.yourcorp.ExceptionHandler"/>

</global-exceptions>

<!-- A global-forward is retrieved by the ActionMapping findForward method. When the findForward method can't find a locally defined forward with the specified name, it searches the global-forwards available and return the one it finds.-->
<global-forwards>
<forward name="logoff" path="/logoff"/>
<forward name="logon" path="/logon.jsp"/>
</global-forwards>

<!-- Actionn Mappings -->
<action-mappings>
<action path="/validateRegistration" type="com.dd.merchant.wsp.Actions.ValidateRegistration" validate="true" input="" name="registrationForm">
<forward name="success" path="/logon.jsp">
</forward>
</action>
</action-mappings>

<!-- Message Resources -->
<message-resources parameter="wsppaymentsweb.resources.ApplicationResources"/>

<!-- Plug-ins -->
<plug-in className="org.apache.struts.validator.ValidatorPlugIn">
<set-property property="pathnames" value="/WEB-INF/validator-rules.xml,/WEB-INF/validation.xml"/>
</plug-in>

Submitted by Raju Krishnam ( [email protected] )


______________

Struts-Config.xml is one of the most important part of any web application based on Sturts. This file is responsible for instructing the Struts what forms are available, what actions are available, and also allows a number of plug-in models to be added to the base Struts package. It can contain Data Source Configuration,Form Bean Definitions, Global Forward Definitions,Action Mapping Definitions, Message Resources Definitions etc.



The most important are Form Bean Definitions, Global Forward Definitions,Action Mapping Definitions.



The <form-bean/> is configured using only two attributes, name and type and doesn't contain any body. The form-bean tag is used to describe an instance of a particular Form Bean that will be later bound to action.

The attribute name specifies the name of the form bean, which is a unique identifier to this form bean & the attribute type specifies the absolute path of the class file.



<global-forwards/>: It is also configured using only two attributes, name and path and there is also an optional attribute redirect. The <forward/> specifies the mapping of a logical name to a context-relative URI path. In the above sample xml file we can see, one of the <forward/> is specified with the name as failure and its corresponding path as index.jsp. That means whenever the logical name failure is encountered the action will be forwarded to the index.jsp page.

The optional attribute redirect is set to false by default. When it is set to true it causes the ActionServlet to use HttpSevletResponse.sendRedirect() method.



<action-mappings/>: The action mapping mainly defines the mapping between the logical Action name and the physical action class. Now lets have an understanding about its attributes.

· The attribute path must be compulsorily defined and it should start with a '/' character. It specifies the context relative path of the submitted request.

· The type attribute specifies the absolute path of the fully qualified class name of the Action class.

· The attribute name must be the same as that of the form bean name for which you want to associate the action.

· The attribute scope specifies the scope of the particular form bean which is an optional one and its default value is session.

· The next attribute validate is also an optional one which by default is set to true. When set to true, the validate() method in the form bean is called which gets associated with a particular Action.

· The next attribute, input is also optional. Whenever a validation error is encountered then the control returns to the path specified in the input attribute.



<controller/>: The <controller/> can be used to modify the default behaviour of the Struts Controller i.e, we can define a RequestProcessor.

Submitted by Puneet Chopra ([email protected])

_________

In struts-config.xml, we define all the global-forwards, action mappings, view mappings, form-bean mappings, controller mapping and finally message-resources declaration if any.

Why we need to declare means, the Controller servelet defined in struts internally looks for this xml file for its proceddings. In real scenario, that the controller servlet inplemented internally is nothing but a slave to this struts-config.xml. The information provided in this file is nothing but like the intelligence to the controller servlet to say - what to do in which situation ?

So, Controller servlet, needs this file to proceede/ run the application.

Submitted by Sagar GV ([email protected])

In struts-config.xml we define Date Sources / Form Beans / Global Exceptions / Global Forwards / Action Mappings / Message Resources / Plug-ins

Example :

<!-- Date Sources -->
<data-sources>
<data-source autoCommit="false" description="First Database Config" driverClass=" org.gjt.mm.mysql.Driver" maxCount="4" minCount="2" password="admin" url="jdbc: mysql://localhost/ARTICLEDB" user="admin">
</<data-sources>
<!-- Form Beans -->
<form-beans>
<form-bean name="registrationForm" type="com.aaa.merchant.wsp.ActionForms.RegistrationForm">
</form-bean>

<!-- Global Exceptions -->
<global-exceptions>
<exception key="some.key" type="java.io.IOException" handler="com.yourcorp.ExceptionHandler"/>

</global-exceptions>

<!-- A global-forward is retrieved by the ActionMapping findForward method. When the findForward method can't find a locally defined forward with the specified name, it searches the global-forwards available and return the one it finds.-->
<global-forwards>
<forward name="logoff" path="/logoff"/>
<forward name="logon" path="/logon.jsp"/>
</global-forwards>

<!-- Actionn Mappings -->
<action-mappings>
<action path="/validateRegistration" type="com.dd.merchant.wsp.Actions.ValidateRegistration" validate="true" input="" name="registrationForm">
<forward name="success" path="/logon.jsp">
</forward>
</action>
</action-mappings>

<!-- Message Resources -->
<message-resources parameter="wsppaymentsweb.resources.ApplicationResources"/>

<!-- Plug-ins -->
<plug-in className="org.apache.struts.validator.ValidatorPlugIn">
<set-property property="pathnames" value="/WEB-INF/validator-rules.xml,/WEB-INF/validation.xml"/>
</plug-in>

Submitted by Raju Krishnam ( [email protected] )


______________

Struts-Config.xml is one of the most important part of any web application based on Sturts. This file is responsible for instructing the Struts what forms are available, what actions are available, and also allows a number of plug-in models to be added to the base Struts package. It can contain Data Source Configuration,Form Bean Definitions, Global Forward Definitions,Action Mapping Definitions, Message Resources Definitions etc.



The most important are Form Bean Definitions, Global Forward Definitions,Action Mapping Definitions.



The <form-bean/> is configured using only two attributes, name and type and doesn't contain any body. The form-bean tag is used to describe an instance of a particular Form Bean that will be later bound to action.

The attribute name specifies the name of the form bean, which is a unique identifier to this form bean & the attribute type specifies the absolute path of the class file.



<global-forwards/>: It is also configured using only two attributes, name and path and there is also an optional attribute redirect. The <forward/> specifies the mapping of a logical name to a context-relative URI path. In the above sample xml file we can see, one of the <forward/> is specified with the name as failure and its corresponding path as index.jsp. That means whenever the logical name failure is encountered the action will be forwarded to the index.jsp page.

The optional attribute redirect is set to false by default. When it is set to true it causes the ActionServlet to use HttpSevletResponse.sendRedirect() method.



<action-mappings/>: The action mapping mainly defines the mapping between the logical Action name and the physical action class. Now lets have an understanding about its attributes.

· The attribute path must be compulsorily defined and it should start with a '/' character. It specifies the context relative path of the submitted request.

· The type attribute specifies the absolute path of the fully qualified class name of the Action class.

· The attribute name must be the same as that of the form bean name for which you want to associate the action.

· The attribute scope specifies the scope of the particular form bean which is an optional one and its default value is session.

· The next attribute validate is also an optional one which by default is set to true. When set to true, the validate() method in the form bean is called which gets associated with a particular Action.

· The next attribute, input is also optional. Whenever a validation error is encountered then the control returns to the path specified in the input attribute.



<controller/>: The <controller/> can be used to modify the default behaviour of the Struts Controller i.e, we can define a RequestProcessor.

Submitted by Puneet Chopra ([email protected])

_________

In struts-config.xml, we define all the global-forwards, action mappings, view mappings, form-bean mappings, controller mapping and finally message-resources declaration if any.

Why we need to declare means, the Controller servelet defined in struts internally looks for this xml file for its proceddings. In real scenario, that the controller servlet inplemented internally is nothing but a slave to this struts-config.xml. The information provided in this file is nothing but like the intelligence to the controller servlet to say - what to do in which situation ?

So, Controller servlet, needs this file to proceede/ run the application.

Submitted by Sagar GV ([email protected]) Source: CoolInterview.com

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