In this example, we can validate user input of the particular regular expressions using this @Pattern annotation and pass some required regular expression values to the regexp attribute.
Development Process:
1. Keep Eclipse IDE ready
2. Project Structure
3. Add the jar file
4. Configure Spring DispacherServlet
5. Add configuration to the file
6. Create Bean Class
7. Create a View Page
8. Create Controller Class
9. Run the App
1. Keep Eclipse IDE ready
2. Project Structure
3. Add the jar file
4. Configure Spring DispacherServlet
web.xml:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4.xsd" id="WebApp_ID" version="4.0">
<display-name>spring-mvc-regular-expression-validation-demo</display-name>
<absolute-ordering />
<!-- Spring MVC Configs -->
<!-- Configure Spring MVC Dispatcher Servlet -->
<servlet>
<servlet-name>dispatcher</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/dispatcher-servlet.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<!-- Set up URL mapping for Spring MVC Dispatcher Servlet -->
<servlet-mapping>
<servlet-name>dispatcher</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
</web-app>→ The file is created in the WEB-INF directory in the application(spring_mvc_regular_expression_validation_demo)
5. Add configuration to file
dispatcher-servlet.xml:
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:mvc="http://www.springframework.org/schema/mvc"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/mvc
http://www.springframework.org/schema/mvc/spring-mvc.xsd">
<!-- Add support for component scanning -->
<context:component-scan base-package="com.poc" />
<!-- Add support for conversion, formatting and validation support -->
<mvc:annotation-driven/>
<!-- Define Spring MVC view resolver -->
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix" value="/WEB-INF/view/" />
<property name="suffix" value=".jsp" />
</bean>
</beans>6. Create Bean Class
User.java:
package com.poc.controller.bean;
import javax.validation.constraints.Pattern;
public class User {
private String firstName;
private String lastName;
@Pattern(regexp = "^[0-9A-Z@#$&%*]+$", message = "This accepts 1 range or more than 1 range")
private String password;
public User() {
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}→ Add validation rule in this bean we are using @Pattern(regexp = “^[1-9a-z]+$”, message = “This accepts 1 range or more than 1 range”) is validating field matches with this expression if failed then the message is shown.
7. Create a View Page
home.jsp:
<%@ page language="java" contentType="text/html; charset=ISO-8859-1" pageEncoding="ISO-8859-1"%>
<!DOCTYPE html>
<html>
<head>
<body>
<a href="http://localhost:8080/spring_mvc_regular_expression_validation_demo/user/showForm">Click For User Form</a>
</body>
</html>user-form.jsp:
<%@ taglib prefix="form" uri="http://www.springframework.org/tags/form"%>
<!DOCTYPE html>
<html>
<head>
<title>User Registration Form</title>
<style>
.error {color:red}
</style>
</head>
<body>
<form:form action="processForm" modelAttribute="user">
First name: <form:input path="firstName" />
<br>
<br>
Last name: <form:input path="lastName" />
<br>
<br>
Password (*): <form:password path="password" />
<form:errors path="password" cssClass="error" />
<br>
<br>
<input type="submit" value="Submit" />
</form:form>
</body>
</html>→ <form:errors path=”password” cssClass=”error” />is displaying a message when the password field fails to validate the specific pattern of the rule.
user-detail.jsp:
<!DOCTYPE html>
<html>
<head>
<title>User Detail</title>
</head>
<body>User Name: ${user.firstName} ${user.lastName} <br>
Password:${user.password}
</body>
</html>8. Create Controller Class
HomeController.java:
package com.poc.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
@Controller
public class HomeController {
@RequestMapping("/")
public String showPage() {
return "home";
}
}UserController.java:
package com.poc.controller;
import javax.validation.Valid;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import com.poc.controller.bean.User;
@Controller
@RequestMapping("/user")
public class UserController{
@RequestMapping("/showForm")
public String showForm(Model theModel) {
// create a User object
User user=new User();
theModel.addAttribute("user",user);
return "user-form";
}
@RequestMapping("/processForm")
public String processForm(@ModelAttribute("user") @Valid User user,BindingResult bindingResult){
if (bindingResult.hasErrors()) {
return "user-form";
}
else {
return "user-detail";
}
}
}→ @Valid is performing validation rules on the User object.
→ The Outcome of the validation is placed on the BindingResult Interface.
9. Run the App
Conclusion:
This example explains How to use regular expression validation. How to put in the validation rules to Bean class? How to use <form:errors/> tag?