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Spring Tutorial

Spring MVC Validation

Spring MVC validation is used to limit the input provided by users. To validate user input, Spring 4or higher version supporting and using Bean Validation API. It can validate both server-side and client-side applications at the same time.

Bean Validation API

Bean Validation API is a Java specification that can be used to apply constraints to object models through annotations. Here, we can validate length, numbers, regular expressions, etc. In addition, we can also provide custom validation.

Since Bean Validation API is just a specification, it needs to be implemented. Therefore, for this, it uses Hibernate Validator. Hibernate Validator is fully compatible with JSR-303/309Implementation, allowing expression and validation of application constraints.

Validation comments

Let's take a look at some commonly used validation comments.

CommentDescription
@NotNullIt determines that the value cannot be empty.
@MinEnsure that the number must be equal to or greater than the specified value.
@MaxEnsure that the number must be equal to or less than the specified value.
@Size@Size
determines that the size must be equal to the specified value.@Pattern

it determines that the sequence follows the specified regular expression.

Spring MVC validation example*In this example, we have created a simple form containing input fields. Here, (

1) indicates that the corresponding field must be entered. Otherwise, the table will produce an error.

、Add dependencies to the pom.xml file. 

<!--　.//https:/mvnrepository.com/pom.xml/spring-org.springframework　-->
validator
　　　　webmvc/<groupId>org.hibernate.validator<
　　　　<groupId>org.springframework<-<artifactId>spring/<artifactId>validator<
　　　　<version>5<artifactId>jstl<1<artifactId>jstl<1webmvc</version>
</dependency>
<!--　.//https:/mvnrepository.com/.RELEASE</org.apache.tomcat-tomcat　-->
validator
　　　　jasper/<groupId>org.hibernate.validator<
　　　　<groupId>org.apache.tomcat<-<artifactId>tomcat/<artifactId>validator<
　　　　<version>9.0.12</version>
</dependency>
　　　　<!--　.//https:/mvnrepository.com/alpha/alpha-jasper<　-->
validator　　
　　　　jstl/<groupId>org.hibernate.validator<　　
　　　　api-<artifactId>servlet/<artifactId>validator<　　
　　　　<version>3api<-.0-1</version>　　
</dependency>
<!--　.//https:/mvnrepository.com/alpha/javax.servlet　-->
validator
　　　　jstl/<groupId>org.hibernate.validator<
　　　　<groupId>javax.servlet</<artifactId>validator<
　　　　<version>1<artifactId>jstl<2</version>
</dependency>
　<!--　.//https:/mvnrepository.com/artifact/org.hibernate.validator-hibernate　-->
validator
　　　　<dependency>/<groupId>org.hibernate.validator<
　　　　<artifactId>hibernate-validator</<artifactId>validator<
　　　　<version>6.0.13.Final</version>
</dependency>

2、Create bean class

Employee.java 

package com.w3codebox;
import javax.validation.constraints.Size;
public class Employee {
　　private String name;
　　@Size(min=1,message="required")
　　private String pass;
　　
　　public String getName() {
　　　　return name;
　　}
　　public void setName(String name) {
　　　　this.name = name;
　　}
　　public String getPass() {
　　　　return pass;
　　}
　　public void setPass(String pass) {
　　　　this.pass = pass;
　　}　
}

3create a controller class

In the controller class:

@ValidAnnotations apply validation rules to the provided object. BindingResult The interface includes the validation result. 

package com.w3codebox;
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;
@Controller
public class EmployeeController {
　　@RequestMapping("/hello")
　　public String display(Model m)
　　{
　　　　m.addAttribute("emp", new Employee());
　　　　return "viewpage";
　　}
　　@RequestMapping("/helloagain")
　　public String submitForm(@Valid @ModelAttribute("emp") Employee e, BindingResult br)
　　{
　　　　if(br.hasErrors())
　　　　{
　　　　　　return "viewpage";
　　　　}
　　　　else
　　　　{
　　　　return "final";
　　　　}
　　}
}

4providing the controller entries in the web.xml file

web.xml 

<?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/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
　　<display-name>SpringMVC</display-name>
　　　<servlet>　　
　　　　<servlet-name>spring</servlet-name>　　
　　　　<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>　　
　　　　<load-on-startup>1</load-on-startup>　　　　
</servlet>　　
<servlet-mapping>　　
　　　　<servlet-name>spring</servlet-name>　　
　　　　<url-pattern>/</url-pattern>　　
</servlet-mapping>　　
</web-app>

5Define Bean in xml file

spring-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">
　　<!--　Provide support for component scanning　-->
　　<context:component-scan base-package="com.w3codebox"　/>
　　<!--Provide support for conversion, formatting and validation　-->
　　<mvc:annotation-driven/>
　　<!--　Define Spring MVC view resolver　-->
　　　　　<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
　　　　　　　　<property name="prefix" value="/WEB-INF/jsp/></property>
　　　　　　　　<property name="suffix" value=".jsp"></property>　　　　　
　　　　　</bean>
</beans>

6Create Request Page

index.jsp 

<%@　taglib　prefix="form"　uri="http://www.springframework.org/tags/form"　%>
<html>
<body>
<a　href="hello">Click　here...</a>
</body>
</html>

7Create Other View Components

viewpage.jsp 

<%@　taglib　prefix="form"　uri="http://www.springframework.org/tags/form"　%>
<html>
<head>
<style>
.error{color:red}
</style>
</head>
<body>
<form:form　action="helloagain"　modelAttribute="emp">
Username:　<form:input　path="name"/>　<br><br>
Password(*):　<form:password　path="pass"/>　　
<form:errors　path="pass"　cssClass="error"/><br><br>
<input　type="submit"　value="submit">
</form:form>
</body>
</html>

final.jsp 

<html>
<body>
Username:　${emp.name}　<br><br>
Password:　${emp.pass}
</body>
</html>

Output:


Let's submit the form without entering the password.


Now, we enter the password and then submit the form.



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