Java Practical info

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<span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">In this post , you will learn
what form beans is, what its importance is, how to use form beans in struts
application, and then the validation mechanisms to validate the struts form
fields like programmatic and declarative, validation at server side and cliet
side. First we will start with what form beans is and what is its importance,
the following section describes what form beans is.<o:p></o:p></span></div>
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<b><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Form
Bean<o:p></o:p></span></b></div>
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<span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Form Bean in struts framework
is a simple java bean class that is a subtype of
org.apache.struts.action.ActionForm class. Form Beans provides a proper
mechanism to exchange the data between the view and actions with reduced
dependency i.e this serves as a transfer object pattern some times known as
Data Transfer Object(DTO). A part from this form beans separates the form data
conversions and validations from actions, which reduces the complexity of the
actions and provides a proper responsibility division. Note: It is not
recommended to use form beans as a Transfer Object for transferring the data
between the controller and Model since form beans are dependent on struts API
and it is not better practice to increase dependency in such a way.<o:p></o:p></span></div>
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<b><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Need of
Form Beans<o:p></o:p></span></b></div>
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<span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Most of the Actions designed in
struts applications are required to process the form data and in all such an
actions if we try to obtain form data using getParameter() method of
ServletRequest, we will face the following problems<o:p></o:p></span></div>
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<span style="font-family: Wingdings; font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"> Ø<span style="font-family: 'Times New Roman'; font-size: 7pt; line-height: normal;">  </span></span><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Dependency
between the view & actions increases<o:p></o:p></span></div>
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<span style="font-family: Wingdings; font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"> Ø<span style="font-family: 'Times New Roman'; font-size: 7pt; line-height: normal;">  </span></span><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Data
conversions has to be performed from actions , which increases the complexity
of the action classes, affects the understandability of the action classes and
if the same conversions are required with different forms data then either
we  need to implement them independently
or need to develop out own library.<o:p></o:p></span></div>
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<span style="font-family: Wingdings; font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"> Ø<span style="font-family: 'Times New Roman'; font-size: 7pt; line-height: normal;">  </span></span><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Affects
the productivity<o:p></o:p></span></div>
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<span style="font-family: Wingdings; font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"> Ø<span style="font-family: 'Times New Roman'; font-size: 7pt; line-height: normal;">  </span></span><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">If any
validations are required for the form fields , they have to be performed in
action class, which once again increases the complexity<o:p></o:p></span></div>
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<b><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Benefits
of Form Beans<o:p></o:p></span></b></div>
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<span style="font-family: Wingdings; font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"> Ø<span style="font-family: 'Times New Roman'; font-size: 7pt; line-height: normal;">  </span></span><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Form
Beans provides the following benefits:<o:p></o:p></span></div>
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<span style="font-family: Wingdings; font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"> Ø<span style="font-family: 'Times New Roman'; font-size: 7pt; line-height: normal;">  </span></span><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Separates
the form data conversions and validations from actions<o:p></o:p></span></div>
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<span style="font-family: Wingdings; font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"> Ø<span style="font-family: 'Times New Roman'; font-size: 7pt; line-height: normal;">  </span></span><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Serves
as a transfer object  between the view
and controller i.e this follows Transfer Object pattern some times known as
Data Transfer Object(DTO)<o:p></o:p></span></div>
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<b><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Using
Form bean in Struts application:<o:p></o:p></span></b></div>
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<span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Using form beans in struts
application is a simple two-step operation, first write a form bean class and
then configure the form bean to work with the struts application, the following
section describes about these two operation in detail.<o:p></o:p></span></div>
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<b><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Writing
a Struts Form bean class<o:p></o:p></span></b></div>
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<span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">The regular form bean class is a java class that satisfies
the following rules:<o:p></o:p></span></div>
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<span style="font-family: Wingdings; font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"> Ø<span style="font-family: 'Times New Roman'; font-size: 7pt; line-height: normal;">  </span></span><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">The
form bean class should be a public non-abstract class<o:p></o:p></span></div>
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<span style="font-family: Wingdings; font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"> Ø<span style="font-family: 'Times New Roman'; font-size: 7pt; line-height: normal;">  </span></span><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">The
form bean class should be a subtype of org.apache.struts.action.ActionForm<o:p></o:p></span></div>
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<span style="font-family: Wingdings; font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"> Ø<span style="font-family: 'Times New Roman'; font-size: 7pt; line-height: normal;">  </span></span><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">Form
bean class should have no-argument constructor ,we are allowed to have multiple
constructors as per our applications requirement<o:p></o:p></span></div>
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<span style="font-family: Wingdings; font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"> Ø<span style="font-family: 'Times New Roman'; font-size: 7pt; line-height: normal;">  </span></span><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">The
form bean class should have a set and get method for each of the property that
it has to represented, where these set and get methods should be public as
written according to the java bean standards.<o:p></o:p></span></div>
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<span style="font-family: Wingdings; font-size: 12.0pt; line-height: 115%; mso-bidi-font-family: Wingdings; mso-fareast-font-family: Wingdings;"> Ø<span style="font-family: 'Times New Roman'; font-size: 7pt; line-height: normal;">  </span></span><span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">The
form bean class can optionally override reset()and validate() methods of Action
Form, you will learn more about reset() and validate() methods in detail in the
next post.<o:p></o:p></span></div>
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<span style="font-family: "Georgia","serif"; font-size: 12.0pt; line-height: 115%;">The following code snippet shows a regular form bean class
that is designed to represent a login form with two properties, uname of type
java.lang.String and pass of type java.lang.String.<o:p></o:p></span></div>
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FormBean's and Validation

In this post , you will learn what form beans is, what its importance is, how to use form beans in struts application, and then the valid...