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Validator Methods in Java Creator bar code 39 in Java Validator Methods




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Validator Methods use tomcat code 39 full ascii implement topaint barcode code39 for java Oracle Reports Overview The second way we can implem j2se Code 3/9 ent custom validation is by adding validation methods to one or more of the application"s managed beans. The following Java class illustrates the use of validator methods for JSF validation:. package net.ensode.glassfish book.

jsfcustomval; import import import import javax.faces.application.

FacesMessage; javax.faces.component.

UIComponent; javax.faces.component.

html.HtmlInputText; javax.faces.

context.FacesContext; [ 187 ]. JavaServer Faces import java Code 39 Extended for Java x.faces.validator.

ValidatorException; import org.apache.commons.

lang.StringUtils; public class AlphaValidator { public void validateAlpha(FacesContext facesContext, UIComponent uiComponent, Object value) throws ValidatorException { if (!StringUtils.isAlphaSpace((String) value)) { HtmlInputText htmlInputText = (HtmlInputText) uiComponent; FacesMessage facesMessage = new FacesMessage(htmlInputText.

getLabel() + ": only alphabetic characters are allowed."); throw new ValidatorException(facesMessage); } } }. In this example, the class c ontains only the validator method. We can give our validator method any name we want; however, its return value must be void, and it must take the three parameters illustrated in the example, in that order. In other words, except for the method name, the signature of a validator method must be identical to the signature of the validate() method defined in the javax.

faces. validator.Validator interface.

As we can see, the body of the above validator method is nearly identical to the body of our custom validator"s validate() method. We check the value entered by the user to make sure it contains only alphabetic characters and/or spaces, if it does not, then we throw a ValidatorException passing an instance of FacesMessage containing an appropriate error message String..

StringUtils In the example, jboss ANSI/AIM Code 39 we used org.apache.commons.

lang.StringUtils to perform the actual validation logic. In addition to the method used in the example, this class contains several methods for verifying that a String is numeric or alphanumeric.

This class, part of the Jakarta commons-lang library, is very useful when writing custom validators.. [ 188 ]. 6 . As every validator method mu st be in a managed bean, we need to declare the bean containing the validator method(s) in the application"s faces-config.xml file..

<faces-config xmlns="http jvm Code 3 of 9 ://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.

w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.

com/xml/ns/javaee http:// java.sun.com/xml/ns/javaee/web-facesconfig_1_2.

xsd" version="1.2"> <managed-bean> <managed-bean-name>Customer</managed-bean-name> <managed-bean-class> net.ensode.

glassfishbook.jsfcustomval.Customer </managed-bean-class> <managed-bean-scope>request</managed-bean-scope> </managed-bean> <managed-bean> <managed-bean-name>AlphaValidator</managed-bean-name> <managed-bean-class> net.

ensode.glassfishbook.jsfcustomval.

AlphaValidator </managed-bean-class> <managed-bean-scope>application</managed-bean-scope> </managed-bean> <navigation-rule> <from-view-id>/customer_data_entry.jsp</from-view-id> <navigation-case> <from-outcome>save</from-outcome> <to-view-id>/confirmation.jsp</to-view-id> </navigation-case> </navigation-rule> <validator> <validator-id>emailValidator</validator-id> <validator-class> net.

ensode.glassfishbook.jsfcustomval.

EmailValidator </validator-class> </validator> </faces-config>. The last thing we need to do to use our validator method is to bind it to our component via the tag"s validator attribute.. <%@ page language="java" tomcat Code39 contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@ taglib uri="http://java.sun.com/jsf/core" prefix="f"%> <%@ taglib uri="http://java.

sun.com/jsf/html" prefix="h"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" [ 189 ].

JavaServer Faces "http://www .w3.org/TR/html4/loose.

dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <style type="text/css"> .leftAlign { text-align: left;} .rightAlign { text-align: right;} </style> <title>Enter Customer Data</title> </head> <body> <f:view> <h:form> <h:messages></h:messages> <h:panelGrid columns="2" columnClasses="rightAlign,leftAlign"> <h:outputText value="First Name:"> </h:outputText> <h:inputText label="First Name" value="#{Customer.

firstName}" required="true" validator="#{AlphaValidator.validateAlpha}"> <f:validateLength minimum="2" maximum="30"></f:validateLength> </h:inputText> <h:outputText value="Last Name:"></h:outputText> <h:inputText label="Last Name" value="#{Customer.lastName}" required="true" validator="#{AlphaValidator.

validateAlpha}"> <f:validateLength minimum="2" maximum="30"></f:validateLength> </h:inputText> <h:outputText value="Email:"> </h:outputText> <h:inputText label="Email" value="#{Customer.email}"> <f:validator validatorId="emailValidator" /> </h:inputText> <h:panelGroup></h:panelGroup> <h:commandButton action="save" value="Save"></h:commandButton> </h:panelGrid> </h:form> </f:view> </body> </html> [ 190 ]. 6 . Because neither the first na me nor the last name fields should accept anything other than alphabetic characters or spaces, we added our custom validator method to both of these fields. After following all of the previous steps, we can now see our validator method in action..

Notice how for the First Nam barcode 39 for Java e field, both our custom validator message and the standard length validator were executed. Implementing validator methods has the advantage of not having the overhead of creating a whole class just for a single validator method (our example does just that, but in many cases validator methods are added to an existing managed bean containing other methods); however, the disadvantage is that each component can only be validated by a single validator method. When using validator classes, several <f:validator> tags can be nested inside the tag to be validated; therefore multiple validations, both custom and standard, can be done on the field.

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