DynaActionForm
Beans are the extension of Form Beans that allows you to specify the form
properties inside the struts configuration file instead of creating a seperate
concreate class. It will become tedious to create a seperate form bean for each
action class. Using DynaActionForm we can easily create Form Bean in
struts-config.xml file. The struts-config.xml file entry for the DyanActionForm
Bean is shown below.
1.<form-beans>
2.<form-bean name="LoginForm"type="org.apache.struts.action.DynaActionForm">
3.<form-property name="userName" type="java.lang.String" />
4.<form-property name="password" type="java.lang.String" />
5.</form-bean>
6.</form-beans>
The type attribute
points to org.apache.struts.action.DynaActionForm and the <form-property>
tag is used to define all the form variables. The <form-property> tag has
the following three attributes.
·
name - The unique name of the
property.
·
initial - The default value of the
property.
·
type - Defines the Java type of the
property. The available types are
o
java.math.BigDecimal
o
java.math.BigInteger
o
boolean and java.lang.Boolean
o
byte and java.lang.Byte
o
char and java.lang.Character
o
java.lang.Class
o
double and java.lang.Double
o
float and java.lang.Float
o
int and java.lang.Integer
o
long and java.lang.Long
o
short and java.lang.Short
o
java.lang.String
o
java.sql.Date
o
java.sql.Time
o
java.sql.Timestamp
Now we will see how
to access the DyanActionForm in the action class.
01.public class LoginAction extends org.apache.struts.action.Action {
02.
03.public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)throwsException {
04.DynaActionForm
loginForm = (DynaActionForm) form;
05.String userName =
loginForm.get("userName").toString();
06.String password =
loginForm.get("password").toString();
07.if(userName.equals(password))
08.{
09.return mapping.findForward("success");
10.}
11.else
12.{
13.return mapping.findForward("failure");
14.}
15.}
16.}
We need to typecast
the form object to DynaActionForm object in the execute method of the action
class. After that we can access the Form Bean properties. We will consider a
simple login application for our example. Here we will check the user name and
password, if they are equal then we will forward the user to the success page,
else we will forward the user to the failue page.
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