Back to: Java Struts Tutorials
Struts 2 Validation with Examples
In this article, I am going to discuss Struts 2 Validation with Examples. Please read our previous article where we discussed Struts 2 Email.
Struts 2 Validation Example
When a user enters data into a webpage, the data needs to be double-checked. This is because sometimes users may enter wrong information (by mistake or on purpose). This checking is supposed to happen in the webpage JavaScript. However, a second round of validation has to be performed in the application as well.
Step 1: Create a new maven project in Eclipse. We will use Maven to manage the dependencies of struts2. This way, we do not have to import JARs.
Remember to set the packaging to war. This is because we shall be deploying a web application.
Finally, click on the finish button to create the project. The following project directories need to be created:
Step 2: Initially, the pom.xml file should contain the following content:
Modify pom.xml to add the required dependencies and the build configuration:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.dotnet</groupId> <artifactId>strutex</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>war</packaging> <dependencies> <dependency> <groupId>org.apache.struts</groupId> <artifactId>struts2-core</artifactId> <version>6.1.2.1</version> </dependency> <dependency> <groupId>org.apache.struts</groupId> <artifactId>struts2-convention-plugin</artifactId> <version>6.1.2.1</version> </dependency> <dependency> <groupId>org.apache.struts</groupId> <artifactId>struts-taglib</artifactId> <version>1.3.10</version> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>2.3</version> </dependency> <dependency> <groupId>taglibs</groupId> <artifactId>standard</artifactId> <version>1.1.2</version> </dependency> <dependency> <groupId>javax.servlet.jsp.jstl</groupId> <artifactId>jstl-api</artifactId> <version>1.2</version> </dependency> <dependency> <groupId>javax.servlet.jsp</groupId> <artifactId>javax.servlet.jsp-api</artifactId> <version>2.3.3</version> <scope>provided</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>3.11.0</version> <configuration> <source>17</source> <target>17</target> </configuration> </plugin> </plugins> </build> </project>
Step 3: In the src/main/webapp directory, create a new file called index.jsp. Add the following content to the file:
<%@ page language = "java" contentType = "text/html; charset = ISO-8859-1" pageEncoding = "ISO-8859-1"%> <%@ taglib prefix = "s" uri = "/struts-tags"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <title>Student Form</title> </head> <body> <s:form action = "StudentInfo" method = "post"> <s:textfield name = "name" label = "Name: " size = "20"/> <s:textfield name = "age" label = "Age: " size = "20"/> <s:submit name = "submit" label = "Submit" align = "center"/> </s:form> </body> </html>
Step 4: In the src/main/webapp directory, create a new file called success.jsp. Add the following content to the file:
<%@ page contentType = "text/html; charset = UTF-8" %> <%@ taglib prefix = "s" uri = "/struts-tags" %> <html> <head> <title>Success</title> </head> <body> Student information was saved successfully. </body> </html>
Step 5: In the src/main/java directory, create a new file called StudentAction.java. The file contains the Java action code. This code should be executed when the “Show details” button is clicked. Add the following content to the file:
package com.dotnet; import com.opensymphony.xwork2.ActionSupport; public class StudentAction extends ActionSupport { private String name; private int age; public String execute() { return SUCCESS; } public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public void setAge(int age) { this.age = age; } public void validate() { if (name == null || name.trim().equalsIgnoreCase("")) addFieldError("name", "Name is required!"); if (age < 3 || age > 25) addFieldError("age", "Age must be between 3 and 25"); } }
In this program, the execute function has absolutely no importance, as it returns “SUCCESS” every time. The validation takes place in the validate() function.
Step 6: In the src/main/resources directory, create a new file called struts.xml. The file is responsible for configuring struts2. Add the following content to the 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> <constant name = "struts.devMode" value = "true" /> <package name = "helloworld" extends = "struts-default"> <action name = "StudentAction" class = "com.dotnet.StudentAction" method = "execute"> <result name = "input">/index.jsp</result> <result name = "success">/success.jsp</result> </action> </package> </struts>
Note that there is no error.jsp file in this project. This is because we perform the required validation and fix the data before proceeding. In other words, there is no chance of an error (because we resolve the errors beforehand).
Step 7: In the src/main/webapp directory, create a new directory called WEB-INF. In this directory, create a new file called web.xml. This file is responsible for implementing struts2 in the web application. Add the following content into the file:
<?xml version="1.0" encoding="UTF-8"?> <web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemalocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/web-app_3_0.xsd" id="apache-struts-config-example" version="3.0"> <display-name>Struts Config XML</display-name> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> <filter> <filter-name>struts2</filter-name> <filter-class>org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter</filter-class> </filter> <filter-mapping> <filter-name>struts2</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> </web-app>
Step 8: Compile and execute the program on the Tomcat server. The following page must open in your default web browser:
If you enter some wrong details, the following text will be shown:
Once you enter the proper details, the following webpage will be displayed:
Congratulations! You have successfully implemented validation in struts2.
In the next article, I am going to discuss Struts 2 Localization with Examples. Here, in this article, I try to explain Struts 2 Validation with Examples and I hope you enjoy this Struts 2 with Validation article.