Spring MVC Annotation (JSR-303) Validation Tutorial

Spring MVC providing 3 types of validations hope you remember 🙂 if not have a look into the previous article. Annotation validation is one of them, let us see how to achieve annotation (JSR-303) validations in Spring MVC 3.

Friends, once again i am saying if you don’t know the basic concepts, you will not be able to understand this concept, so please go through these articles, [ignore if you already read]
Spring MVC Execution Flow Diagram, Spring MVC 3.2 Flow
Spring MVC Hello World, Spring MVC 3.2 Hello World Example In Eclipse

• Spring annotation validations are also known as JSR-303 validations
• We need to import javax.validation.constraints.* and org.hibernate.validator.constraints.* [depends upon your requirement, i am using both 🙂 will explain you in the example]
• For that we must have JSR-303 related jar, Hibernate Validator jar [ Don’t confuse..!, this is only for validations, nothing related to hibernate ] in you class path

You can download the same from the Maven repository…

Download validation-api-1.0.0.[JSR-303]
Download hibernate-validator-4.2.0.Final

Syntax

Consider some bean class…

Java4sBean.java

import org.hibernate.validator.constraints.NotEmpty;
import javax.validation.constraints.Size;
public class Java4sBean{

    @NotEmpty
    private String user;

    @NotEmpty(message = "Password should not be blank.")
    @Size(min = 5, max = 8, message = "Password length should be between 5 to 8 Characters.")
    private String pass;

    // Setters and Getters...
}

Then Controller class…

Java4sController.java

@Controller
public class Java4sController {    

        @RequestMapping("/someMappingName")
        public String loginCheck(@Valid Java4sBean bean, BindingResult result, ModelMap model) {

            if (result.hasErrors()) {
                return "loginPage";
            } else {
                model.addAttribute("lfobj", bean);
                return "success";
            }
        }               
}

In Spring Configuration File

In order to support direct bean validation we should do the following changes in your spring configuration file..
After

<context:component-scan base-package="java4s" />

you need to add the following line…

<mvc:annotation-driven />

so that JSR-303 validations will be activated 🙂

Explanation

I have to explain the controller class here, see Java4sController.java line number 5, i have written @Valid Java4sBean bean right, means once the flow came to this line and as we are using @Valid annotation, flow will redirect to Java4sBean and annotation validations will be executed. If  get any errors all those errors will be added to the BindingResult object automatically.  We can consider this BindingResult object as response in java servlets. That’s it friends, Just remember this concept i will explain the flow again in the example 🙂 cheers..!!!!!!!

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• Spring MVC Hello World, Spring MVC 3.2 Hello World Example In Eclipse
• Jars Required For Hibernate Annotations

::. About the Author .::
		Sivateja Kandula - Java/J2EE Full Stack Developer Founder of Java4s - Get It Yourself, A popular Java/J2EE Programming Blog, Love Java and UI frameworks. You can sign-up for the Email Newsletter for your daily dose of Java tutorials.