package com.mezoline.bean;

import javax.faces.application.FacesMessage;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.RequestScoped;
import javax.faces.context.FacesContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;


@ManagedBean
@RequestScoped
public class LoginView {

    private String username;
    private String password;

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String action()
    {
        try {
            HttpServletRequest request = (HttpServletRequest) FacesContext
                    .getCurrentInstance()
                    .getExternalContext()
                    .getRequest();

            request.login(username, password);

        } catch (ServletException e) {
            FacesContext.getCurrentInstance().addMessage("login-form:username",
                    new FacesMessage("Incorrect login or password"));
            return "/login";
        }
        return "/index?faces-redirect=true";
    }
}

<ui:composition template="/WEB-INF/views/layouts/main.xhtml"
                xmlns="http://www.w3.org/1999/xhtml"
                xmlns:f="http://java.sun.com/jsf/core"
                xmlns:h="http://java.sun.com/jsf/html"
                xmlns:p="http://primefaces.org/ui"
                xmlns:pt="http://xmlns.jcp.org/jsf/passthrough"
                xmlns:ui="http://java.sun.com/jsf/facelets"
                xmlns:c="http://java.sun.com/jsp/jstl/core"
>

    <ui:define name="content">
        <p:panel header="Login From">
            <h:form method="post" class="form-horizontal" id="login-form">
                <h:messages style="color:red;margin:8px;" />
                <div class="form-group">
                    <label class="control-label col-sm-2">Username:</label>
                    <div class="col-sm-10">
                        <h:inputText id="username" value="#{loginView.username}" />
                    </div>
                </div>
                <div class="form-group">
                    <label class="control-label col-sm-2">Password:</label>
                    <div class="col-sm-10">
                        <h:inputText id="password" value="#{loginView.password}" />
                    </div>
                </div>
                <div class="form-group">
                    <p:captcha label="Captcha" />
                </div>
                <div class="form-group">
                    <div class="col-sm-offset-2 col-sm-10">
                        <h:commandButton action="#{loginView.action}" value="Login" />
                    </div>
                </div>
            </h:form>
        </p:panel>
    </ui:define>

</ui:composition>

package com.mezoline.bean;

import com.mezoline.domain.Role;
import com.mezoline.domain.User;
import javax.annotation.Resource;
import javax.faces.application.FacesMessage;
import javax.faces.bean.ManagedBean;
import javax.faces.bean.ManagedProperty;
import javax.faces.context.FacesContext;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.transaction.*;
import java.util.ArrayList;

@ManagedBean
public class RegisterView {

    @PersistenceContext
    private EntityManager entityManager;

    @Resource
    private UserTransaction userTransaction;

    @ManagedProperty(value = "#{user}")
    private User user;

    public void setUser(User user) {
        this.user = user;
    }

    public String submit() {
        try {
            userTransaction.begin();
            System.out.println(User.existsByName(entityManager, user.getName()));

            if (User.existsByName(entityManager, user.getName())) {
                FacesContext.getCurrentInstance().addMessage("login-form:username",
                        new FacesMessage(FacesMessage.SEVERITY_ERROR, "Error", "This user already exists"));
                return "";
            }

            Role role = new Role();
            role.setRole_Name(Role.Name.USER);
            role.setUser_name(user.getName());
            ArrayList<Role> roles = new ArrayList<>();
            roles.add(role);
            user.setRoles(roles);
            
            entityManager.persist(user);
            userTransaction.commit();

        } catch (SystemException | NotSupportedException | RollbackException
                | HeuristicMixedException | HeuristicRollbackException e) {

            FacesContext.getCurrentInstance().addMessage("login-form:username",
                    new FacesMessage(FacesMessage.SEVERITY_ERROR, "Sorry", "Error occurred"));
        }

        return "/login";
    }

}