Using Standard Validator & Custom Validator
JSF validation is used to make sure that the component
is going to obtain the expected content, such as:
1. Length is between 1 and 10
2. Float is between 2.0 and 10.0
3. Email address is in correct format etc.
You can implement it using standard validators supplied
by JSF or by creating your own custom validators.
Standard validation
JSF provides standard validators like:
| DoubleRangeValidator |
Value must be numeric type and in
range between minimum and/or maximum values. |
| LongRangeValidator |
Value must be numeric type,
convertible to long and in range between minimum and/or maximum values. |
| LengthValidator |
Value must be string type and length
must be in range between minimum and/or maximum values. |
For Example:
1. <f:validateLength
/> is used to validate whether the length of the value lies in specified
range.
<h:inputText id="name" required="true">
<f:validateLength maximum="10" minimum="1"/>
</h:inputText>
<h:message for="name" />
|
2. <f:validateDoubleRange/> is used to
validate whether the double value lies in specified range.
<h:inputText id="no" required="true">
<f:validateDoubleRange minimum="2.0" maximum="10.0"/>
</h:inputText>
<h:message for="no" />
|
3. <f:validateLongRange"/>
is used to validate whether the long value lies in specified range.
<h:inputText id = "lno" required = "true">
<f:validateLongRange minimum = "2" maximum = "10"/>
</h:inputText><br/>
<h:message for="lno" /> |
Custom validation
If validation for the component value is not
supported by the standard validators then you will need to create your own
validator. For example, you can create email validator to validate the email
text entered by the user i.e. whether the email id is in correct format. Using
custom validator you will be able to display your own validation error message.
Steps to create a custom validator:
1. Create a class that implements the
javax.faces.validator.Validator interface
2. Implement the validate() method (defined in
Validator interface).
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);
}
}
} |
3. Register this validator in the configuration file
"faces-confix.xml".
<validator>
<validator-id>checkvalidemail</validator-id>
<validator-class>roseindia.Validation</validator-class>
</validator> |
4. Use this validator by <f:validator/> tag in
the JSP page.
5. Use <h:message> tag in the jsp page to display the error message.
<h:inputText id="email" required="true">
<f:validator validatorId="checkvalidemail" />
</h:inputText>
<h:message for="email" /> |
Download
code for all examples
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