Struts 2 Url Validator

The URLValidator of Struts 2 Framework checks whether the String contained within the given field is a valid URL or not. If the entered value is not a valid URL, it generates an error message.

The error message is supplied between the <message> </message> tag. The following example demonstrates how to use the URL validator.

Follow the steps to develop the URL validator example:

Step 1: Create the struts.xml file and add the following xml snippet in the struts.xml file.


<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE struts PUBLIC

    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"

    "http://struts.apache.org/dtds/struts-2.0.dtd">



<struts>

    <!-- Rose India Struts 2 Tutorials -->

    <constant name="struts.enable.DynamicMethodInvocation" value="false" />

    <constant name="struts.devMode" value="true" />



    <package name="roseindia" namespace="/roseindia" extends="struts-default">

    

    <!-- Add actions here -->



    <!-- Url validation -->



    <action name="urlValidation">

      <result>/pages/urlInputForm.jsp</result>

    </action>



    <action name="urlValidation1" class="net.roseindia.urlVaLidationAction">

      <result name="input">/pages/urlInputForm.jsp</result>

      <result name="error">/pages/urlInputForm.jsp</result>

            <result>/pages/urlSuccess.jsp</result>

        </action>

    

         <!-- Add actions here -->

    </package>





    <!-- Add packages here -->



</struts>

Step 2 : Create an input jsp form.

urlInputForm.jsp


<%@ taglib prefix="s" uri="/struts-tags" %>



<html>



<head>



<title>Url input form</title>

 <link href="<s:url value="/css/main.css"/>" rel="stylesheet"

          type="text/css"/>

      <s:head/>

</head>



<body>

  

  <s:form method="POST" action="urlValidation1">

   </td>

  </tr>

    <s:textfield label="Enter Url" name="url" />

    <s:submit />

  </s:form>



</body>



</html>

Step 3 : Create an Action class.

urlVaLidationAction.java


package net.roseindia;

import com.opensymphony.xwork2.ActionSupport;



public class urlVaLidationAction extends ActionSupport {



  private String url;



  public void setUrl(String url){

    this.url = url;

  }

  public String getUrl(){

    return url;

  }

}

Step 4 : Create an URL validator as shown:

The validation.xml format is either <ActionClassName>-validation.xml or <ActionClassName>-<ActionAliasName>-validation.xml.

URL validator: This Field Validator checks whether a given field contains a valid URL String or not. If the entered text is valid then you get the urlSuccess.jsp page. Otherwise, it displays the message given in the xml file (like "Please enter a valid URL.").

The URL validator takes the following parameters:

fieldName - It refers to the field name, the URL validator is validating.
It is required if using Plain-Validator Syntax

urlVaLidationAction-validation.xml


<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE validators PUBLIC 

      "-//OpenSymphony Group//XWork Validator 1.0.2//EN" 

      "http://www.opensymphony.com/xwork/xwork-validator-1.0.2.dtd">

      

<validators>



  <field name="url">

    <field-validator type="url">

       <message>Please enter a valid url</message>

    </field-validator>

  </field>



</validators>

When the correct URL is entered the user gets the urlSuccess.jsp page displaying the entered URL.

urlSuccess.jsp


<%@page language="java" %>

<html>



<head>

  <title>Correct entry</title>

</head>



<body>

<b>URL =  </b><%=request.getParameter("url") %>!

</body>



</html>

Output:

When this application executes initially the user gets the following:

If the user enters the wrong URL then he gets:

Again, the user enters the wrong URL then he gets:

If the user enters the correct URL as

then he gets a success message as an output: