# ===============================
# DATABASE
# ===============================

spring.datasource.driver-class-name=com.mysql.jdbc.Driver

spring.datasource.url=jdbc:mysql://localhost:3306/userapp
spring.datasource.username=root
spring.datasource.password=

server.port=9092

# ===============================
# JPA / HIBERNATE
# ===============================

spring.jpa.show-sql=true
spring.jpa.hibernate.ddl-auto=none
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

package entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;

@Entity
@Table(name = "App_User", //
        uniqueConstraints = { //
                @UniqueConstraint(name = "APP_USER_UK", columnNames = "User_Name") })
public class AppUser {

    @Id
    @GeneratedValue
    @Column(name = "User_Id", nullable = false)
    private Long userId;

    @Column(name = "User_Name", length = 36, nullable = false)
    private String userName;

    @Column(name = "Encryted_Password", length = 128, nullable = false)
    private String encrytedPassword;

    @Column(name = "Enabled", length = 1, nullable = false)
    private boolean enabled;

    public Long getUserId() {
        return userId;
    }

    public void setUserId(Long userId) {
        this.userId = userId;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getEncrytedPassword() {
        return encrytedPassword;
    }

    public void setEncrytedPassword(String encrytedPassword) {
        this.encrytedPassword = encrytedPassword;
    }

    public boolean isEnabled() {
        return enabled;
    }

    public void setEnabled(boolean enabled) {
        this.enabled = enabled;
    }

}

package dao;

import javax.persistence.EntityManager;
import javax.persistence.NoResultException;
import javax.persistence.Query;

import entity.AppUser;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;

@Repository
@Transactional
public class AppUserDAO {

    @Autowired
    private EntityManager entityManager;

    public AppUser findUserAccount(String userName) {
        try {
            String sql = "Select e from " + AppUser.class.getName() + " e " //
                    + " Where e.userName = :userName ";

            Query query = entityManager.createQuery(sql, AppUser.class);
            query.setParameter("userName", userName);

            return (AppUser) query.getSingleResult();
        } catch (NoResultException e) {
            return null;
        }
    }

}

2018-05-03 14:45:12.999  WARN 6336 --- [nio-9092-exec-5] o.hibernate.hql.internal.QuerySplitter   : HHH000183: no persistent classes found for query class: Select e from entity.AppUser e  Where e.userName = :userName
2018-05-03 14:45:13.075  INFO 6336 --- [nio-9092-exec-5] o.h.h.i.QueryTranslatorFactoryInitiator  : HHH000397: Using ASTQueryTranslatorFactory

Caused by: java.lang.ArrayIndexOutOfBoundsException: 0
    at org.hibernate.internal.AbstractSharedSessionContract.resultClassChecking(AbstractSharedSessionContract.java:703) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:687) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
    at org.hibernate.internal.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:23) ~[hibernate-core-5.2.14.Final.jar:5.2.14.Final]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_05]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_05]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_05]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_05]
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:304) ~[spring-orm-5.0.4.RELEASE.jar:5.0.4.RELEASE]
    at com.sun.proxy.$Proxy75.createQuery(Unknown Source) ~[na:na]
    at dao.AppUserDAO.findUserAccount(AppUserDAO.java:24) ~[classes/:na]
    at dao.AppUserDAO$$FastClassBySpringCGLIB$$62f41262.invoke(<generated>) ~[classes/:na]
    at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204) ~[spring-core-5.0.4.RELEASE.jar:5.0.4.RELEASE]
    at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:747) ~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163) ~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE]
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139) ~[spring-tx-5.0.4.RELEASE.jar:5.0.4.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE]
    at org.springframework.transaction.interceptor.TransactionInterceptor$$Lambda$375/10311291.proceedWithInvocation(Unknown Source) ~[na:na]
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294) ~[spring-tx-5.0.4.RELEASE.jar:5.0.4.RELEASE]
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98) ~[spring-tx-5.0.4.RELEASE.jar:5.0.4.RELEASE]
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185) ~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE]
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:689) ~[spring-aop-5.0.4.RELEASE.jar:5.0.4.RELEASE]
    at dao.AppUserDAO$$EnhancerBySpringCGLIB$$e269dd5.findUserAccount(<generated>) ~[classes/:na]