JSF validator Tag
This tag is used to add and register the validator to
the nearest parent component. Typically all applications requires filling some
or more information in the page. So it will be better approach to find out the
invalid information value or format as soon as possible to make it user
friendly. So user can find out faults and correct it. JSF provides built-in
validation rules. JSF also helps to customize the validation rules to make
it according to the need. If the component has input value then the
conversion of the value to the required type is needed and then specified
validator type is invoked to check whether this value is of required format and
type.
This tag contains one attribute named "validatorID" which is
required attribute. In this attribute we specify the name of backing bean class
where we write functionality according to our need.For
custom validation Validator interface is implemented in the class providing
validation. You have to maintain the faces-config file where validator-id and
validator-class is specified within the validator element. Here, one thing that
we have to take care is that validator-id in both places (in faces-config file
and validator tag in jsp file ) should match.
Code Description :
<%@ page contentType="text/html" %>
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<f:view>
<html>
<body>
<h:form id="form1">
<table>
<tr>
<td><font color="#FF0000"><h:message for="email" /></font></td>
<td> </td>
</tr>
<tr>
<td>
<h:inputText id="email" required="true">
<f:validator validatorId="checkvalidemail" />
</h:inputText>
</td>
<td><h:commandButton value="Submit" /></td>
</tr>
</table>
</h:form>
</body>
</html>
</f:view> |
Backing Bean (Validation.java) : The code below
is for backing bean used in this example.
package roseindia;
import javax.faces.*;
import javax.faces.validator.*;
import javax.faces.application.*;
import javax.faces.component.*;
import javax.faces.context.*;
import java.util.regex.*;
public class validation implements Validator{
public validation(){}
public void validate(FacesContext facesContext, UIComponent uIComponent, Object object) throws
ValidatorException{
String enteredEmail = (String)object;
Pattern p = Pattern.compile(".+@.+\\.[a-z]+");
Matcher m = p.matcher(enteredEmail);
boolean matchFound = m.matches();
if (!matchFound) {
FacesMessage message = new FacesMessage();
message.setSummary("Invalid Email ID.");
throw new ValidatorException(message);
}
}
} |
Now we have to register this class in the faces-config file like below :
<faces-config>
..................
..................
<validator>
<validator-id>checkvalidemail</validator-id>
<validator-class>roseindia.validation</validator-class>
</validator>
.................
.................
</faces-config> |
Here in this above case "checkvalidemail" specified in "validator-id"
is the alias
name (this will be used in jsp file to access the actual backing bean
class) of the actual class specified in "validator-class" in the
faces-config file. For
ex.
Rendered Output :
If we enter incorrect email address then its validation process makes it
invalid and shows error message to the user, like below.
Html Source Code :
<html>
<body>
<form id="form1" method="post" action="/f-tags/pages/validator/validator.jsf"
enctype="application/x-www-form-urlencoded">
<table>
<tr>
<td><font color="#FF0000"></font></td>
<td> </td>
</tr><tr><td>
<input id="form1:email" type="text" name="form1:email" />
</td>
<td><input type="submit" name="form1:_id1" value="Submit" /></td>
</tr>
</table>
<input type="hidden" name="form1" value="form1" /></form>
</body>
</html> |
This tag contains one attribute :
validatorId : This is the required attribute and is used to specify
the ID of the validator class which we are going to use in this validation
process (in the case of custom validation). This value must match with the
validator-id element specified in validator tag of faces-config file.
|
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