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Struts DynaActionForm
In this tutorial you will learn how to create Struts
DynaActionForm. We will recreate our address form with Struts DynaActionForm.
DynaActionForm is specialized subclass of ActionForm that allows the creation
of form beans with dynamic sets of properties, without requiring the developer
to create a Java class for each type of form bean. DynaActionForm eliminates
the need of FormBean class and now the form bean definition can be written
into the struts-config.xml file. So, it makes the FormBean declarative and
this helps the programmer to reduce the development time.
In this tutorial we will recreate the add form with the
help of DynaActionForm. It also shows you how you can validate use input in
the action class.
Adding DynaActionForm Entry in
struts-config.xml
First we will add the necessary entry in the
struts-config.xml file. Add the following entry in the
struts-config.xml file. The form bean is of
org.apache.struts.action.DynaActionForm type. The
<form-property/> tag is used to define the property for the form
bean. We have defined three properties for our dynamic form bean.
<form-bean name="DynaAddressForm"
type="org.apache.struts.action.DynaActionForm">
<form-property name="name"
type="java.lang.String"/>
<form-property
name="address" type="java.lang.String"/>
<form-property
name="email" type="java.lang.String" />
</form-bean>
Adding action mapping
Add the following action mapping in the struts-config.xml
file:
<action path="/DynaAddress" type="roseindia.net.AddressDynaAction"
name="DynaAddressForm"
scope="request"
validate="true"
input="/pages/DynaAddress.jsp">
<forward name="success" path="/pages/success.jsp"/>
<forward name="invalid" path="/pages/DynaAddress.jsp"
/>
</action>
Creating Action Class
Code for action class is as follows:
package roseindia.net;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.apache.struts.action.DynaActionForm;
import org.apache.struts.action.ActionMessages;
import org.apache.struts.action.ActionMessage;
public class AddressDynaAction extends Action
{
public ActionForward execute(
ActionMapping mapping,
ActionForm form,
HttpServletRequest request,
HttpServletResponse response) throws Exception{
DynaActionForm addressForm = (DynaActionForm)form;
//Create object of ActionMesssages
ActionMessages errors = new ActionMessages();
//Check and collect errors
if(((String)addressForm.get("name")).equals("")) {
errors.add("name",new ActionMessage("error.name.required"));
}
if(((String)addressForm.get("address")).equals("")) {
errors.add("address",new ActionMessage("error.address.required"));
}
if(((String)addressForm.get("email")).equals("")) {
errors.add("email",new ActionMessage("error.emailaddress.required"));
}
//Saves the error
saveErrors(request,errors);
//Forward the page
if(errors.isEmpty()){
return mapping.findForward("success");
}else{
return mapping.findForward("invalid");
}
}
}
Creating the JSP file
We will use the Dyna Form DynaAddressForm created above in the jsp file. Here is the code of the jsp(DynaAddress.jsp) file.
<%@ 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">
<html:form action="/DynaAddress" method="post">
<table>
<tr>
<td align="center" colspan="2">
<font size="4">Please Enter the Following Details</font>
</tr>
<tr>
<td align="left" colspan="2">
<font color="red"><html:errors/></font>
</tr>
<tr>
<td align="right">
Name
</td>
<td align="left">
<html:text property="name" size="30" maxlength="30"/>
</td>
</tr>
<tr>
<td align="right">
Address
</td>
<td align="left">
<html:text property="address" size="30" maxlength="30"/>
</td>
</tr>
<tr>
<td align="right">
E-mail address
</td>
<td align="left">
<html:text property="email" size="30" maxlength="30"/>
</td>
</tr>
<tr>
<td align="right">
<html:submit>Save</html:submit>
</td>
<td align="left">
<html:cancel>Cancel</html:cancel>
</td>
</tr>
</table>
</html:form>
</body>
</html:html>
Add the following line in the index.jsp to call the form.
<li>
<html:link page="/pages/DynaAddress.jsp">Dyna Action Form Example</html:link>
<br>
Example shows you how to use DynaActionForm.
</li>
Building Example and Testing
To
build and deploy the application go to Struts\strutstutorial directory
and type ant on the command prompt. This will deploy the application.
Open the browser and navigate to the DynaAddress.jsp page. Without entering anything in the form and submitting the submit button, your browser should show the following out put.
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