How validation works in Spring using Annotation?

[SunilK Chauhan]

Hi All,

I am a new being in Spring and recently started working on a project.
i am trying to display error message using auto validation but it is not showing even a simple validation message.

LoginPage.java

package net.roseindia.form;

import javax.validation.constraints.Size;

import org.hibernate.validator.constraints.Email;
import org.hibernate.validator.constraints.Length;
import org.hibernate.validator.constraints.NotEmpty;

public class LoginPage {
	
	@NotEmpty
	@Email
	@Size(min = 5, max=10, message = "The field must be at least 5 characters")
	String loginName = "";
	
	@NotEmpty
	@Size(min = 5, message = "The field must be at least 5 characters for Password")
	String loginPassword = "";
	
	public String getLoginName() {
		return loginName;
	}
	public void setLoginName(String loginName) {
		this.loginName = loginName;
	}
	public String getLoginPassword() {
		return loginPassword;
	}
	public void setLoginPassword(String loginPassword) {
		this.loginPassword = loginPassword;
	}
}

and Controller:

import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.validation.Valid;
import javax.validation.Validator;
import net.roseindia.form.LoginPage;
import org.springframework.validation.BindingResult;
import org.springframework.validation.Validator;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.validation.BindingResult;
import org.springframework.web.bind.annotation.ModelAttribute;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;

@Controller
public class LoginPageController {

	@Autowired
	private Validator validator;

	public void setValidate(Validator validate) {
		this.validator = validate;
	}
@RequestMapping(value = "loginPage.html", method = RequestMethod.POST)
	public String saveLoginPage(Map model, @ModelAttribute("loginOb") LoginPage lOb, BindingResult result,
			HttpServletRequest request) {

		validator.validate(lOb, result);
		if (result.hasErrors()) {
			return "loginPage.html";
		}

		LoginPage loginOb = new LoginPage();
		model.put("loginOb", loginOb);
		return "loginPageForm";

	}

Kindly suggest that why it is not working?