Develop Reference

How to fiw 'java.lang.ClassNotFoundException: com.mysql.cj.jdbc.Driver' for liferay

Please help me with fixing ClassNotFoundException here:
java.lang.ClassNotFoundException: com.mysql.cj.jdbc.Driver
Here are some details on it:
I'm loading configs from hibernate.cfg.xm
SessionFactoryConnection.java
public class SessionFactoryConnection {
private static SessionFactory sessionFactory;
static {
Configuration configuration = new Configuration();
configuration = configuration.configure("hibernate.cfg.xml");
sessionFactory = configuration.buildSessionFactory();
}
private SessionFactoryConnection() {
}
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
}
hibernate.cfg.xm
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/company?serverTimezone=UTC</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">1</property>
<property name="hibernate.connection.driver_class">com.mysql.cj.jdbc.Driver</property>
<property name="hbm2ddl.auto\">update</property>
<property `enter code here`name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property>
<mapping class="com.aimprosoft.model.Department"/>
<mapping resource="hbm/Department.hbm.xml"/>
<mapping class="com.aimprosoft.model.Employee"/>
<mapping resource="hbm/Employee.hbm.xml"/>
</session-factory>
</hibernate-configuration>
I'm using
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.15</version>
</dependency>
The Stacktrace:
2019-04-09 12:20:52.063 ERROR [http-nio-8080-exec-1][DriverManagerConnectionProvider:88] JDBC Driver class not found: com.mysql.cj.jdbc.Driver
java.lang.ClassNotFoundException: com.mysql.cj.jdbc.Driver
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1309)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1138)
........
at com.liferay.portal.kernel.portlet.PortletFilterUtil.doFilter(PortletFilterUtil.java:71)
at com.liferay.portal.kernel.servlet.PortletServlet.service(PortletServlet.java:108)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)

Please check whether you added this property in hibernate.cfg.xml file.
<property name = "hibernate.connection.driver_class">
com.mysql.jdbc.Driver
</property>

Hibernate doesn't create table and throw exception

I have a problem with my hibernate project.
When I try to start simple method the Hibernate throw exception:
Exception in thread "main" org.hibernate.exception.SQLGrammarException: could not execute statement
at org.hibernate.exception.internal.SQLExceptionTypeDelegate.convert(SQLExceptionTypeDelegate.java:63)
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:42)
at ...
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Table 'botsender.users' doesn't exist
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:400)
at com.mysql.jdbc.Util.getInstance(Util.java:383)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:980)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3847)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3783)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2447)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2594)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2545)
at ...
I've tried change my xml config but It didn't help.
Here's config:
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.id.new_generator_mappings">false</property>
<property name="hibernate.hbm2ddl">create</property>
<property name="hibernate.bytecode.use_reflection_optimizer">false</property>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.password">admin12345</property>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/botSender</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="show_sql">true</property>
<mapping class="com.bot.entity.User"></mapping>
<mapping class="com.bot.entity.Role"></mapping>
<mapping class="com.bot.entity.Chanel"></mapping>
<mapping class="com.bot.entity.MessageToChanel"></mapping>
<mapping class="com.bot.entity.MessageToUser"></mapping>
<mapping class="com.bot.entity.Status"></mapping>
</session-factory>
And simple test-method is:
public class App
{
public static void main( String[] args )
{
SessionFactory sessionFactory = HibernateAnnotationUtil.getSessionFactory();
Session session = sessionFactory.openSession();
System.out.println("Session created");
Transaction tx = session.beginTransaction();
User user = new User();
user.setFirthName("Igor");
user.setLastName("Petrenko");
user.setNickName("6ruceVVayne");
user.setToken("somethink");
user.setRole(Role.ADMINISTRATOR);
session.save(user);
tx.commit();
System.out.println("User ID=" + user.getId());
}
}
I also tried to change "create" to "update". And change " org.hibernate.dialect.MySQLDialect" to "MySQL5InnoDBDialect". But I still get stuck on the same exception.

Hibernate Java Config Versus Xml

I am new to hibernate and I don't fully understand how to choose between java configuration and xml in hibernate config file? Tutorials that I have watched seem to be out of date. So my question is what is the best and most up to date way of configuring a model to hibernate.
The following is my current approach which seems to be the only one working for me:
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.url">jdbc:mysql://localhost:3306/mydatabase</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password">password</property>
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.pool_size">10</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQL57InnoDBDialect</property>
<property name="hibernate.show_sql">true</property>
<property name="hibernate.format_sql">true</property>
<property name="hibernate.use_sql_comments">true</property>
<property name="hbm2ddl.auto">update</property>
<property name="current_session_context_class">thread</property>
<property name="hibernate.enable_lazy_load_no_trans">true</property>
<!-- <property name="hibernate.generate_statistics">true</property> -->
I am configuring my model in a java file as shown below:
public class HibernateUtil {
private static SessionFactory sessionFactory = buildSessionFactory();
private static SessionFactory buildSessionFactory() {
try {
// Create your SessionFactory with mappings for every Entity in a specific package
Configuration configuration = new Configuration();
configuration.configure();
configuration.addAnnotatedClass(PersonModel.class);
ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties()).build();
SessionFactory sessionFactory = configuration.buildSessionFactory(serviceRegistry);
//SessionFactory sessionFactory = new Configuration().configure("hibernate.cfg.xml").buildSessionFactory();
return sessionFactory;
} catch (Throwable ex) {
// Make sure you log the exception, as it might be swallowed
System.err.println("Initial SessionFactory creation failed." + ex);
throw new ExceptionInInitializerError(ex);
}
}
Is this the right way of doing it? or should it be done via XML file, if so can someone show me an example please?
Thanks in advance

Look at the following docs for examples:
For annotation mapping:
https://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/#entity-mapping
For xml mapping:
https://docs.jboss.org/hibernate/orm/3.3/reference/fr-FR/html/xml.html
Use of one of them it's up to you, for more details you can check this answer or this one
EDIT: mapping example in hibernate configuration file
<hibernate-configuration>
<session-factory>
<mapping package="test.animals"/>
<mapping class="test.Flight"/>
<mapping class="test.Sky"/>
<mapping class="test.Person"/>
<mapping class="test.animals.Dog"/>
<mapping resource="test/animals/orm.xml"/>
</session-factory>
</hibernate-configuration>

This way you can scan all entity classes at once
SessionFactory sessionFactory = new LocalSessionFactoryBuilder(yourDataSource())
.scanPackages("com.yourpackage.name")
.addProperties(properties)
.buildSessionFactory();

Use Two hibernate.cfg.xml files in a Application

how to specify two hibernate configurations for a one application,
i have created two hibernate files and mention them in SessionFactory.util
hibernateMaster.cfg.xml file is working fine..
but when shut down Master database server and try to use application with hibernateMaster.cfg.xml and retrieve data it gives me "null"
but if i restart the Application it is working fine with hibernateMaster.cfg.xml file
here are my hibernate files
hibernateMaster.cfg.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database Connection Settings -->
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://192.168.232.143:3306/cps</property>
<property name="hibernate.connection.username">gaiz</property>
<property name="hibernate.connection.password">mysql</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.show_sql">true</property>
<property name="hibernate.current_session_context_class">thread</property>
<mapping resource="lib/driver/mappings/Patient.hbm.xml"/>
<mapping resource="lib/driver/mappings/Allergy.hbm.xml"/>
<mapping resource="lib/driver/mappings/Hospital.hbm.xml"/>
<mapping resource="lib/driver/mappings/StatStaff.hbm.xml"/>
<mapping resource="lib/driver/mappings/StatWard.hbm.xml"/>
<mapping resource="lib/driver/mappings/User.hbm.xml"/>
<mapping resource="lib/driver/mappings/UserRole.hbm.xml"/>
<mapping resource="lib/driver/mappings/UserLog.hbm.xml"/>
</session-factory>
</hibernate-configuration>
hibernateSlave.cfg.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<!-- Database Connection Settings -->
<property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="hibernate.connection.url">jdbc:mysql://192.168.232.144:3306/cps</property>
<property name="hibernate.connection.username">gaiz2</property>
<property name="hibernate.connection.password">mysql</property>
<property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="hibernate.show_sql">true</property>
<property name="hibernate.current_session_context_class">thread</property>
<mapping resource="lib/driver/mappings/Patient.hbm.xml"/>
<mapping resource="lib/driver/mappings/Allergy.hbm.xml"/>
<mapping resource="lib/driver/mappings/Hospital.hbm.xml"/>
<mapping resource="lib/driver/mappings/StatStaff.hbm.xml"/>
<mapping resource="lib/driver/mappings/StatWard.hbm.xml"/>
<mapping resource="lib/driver/mappings/User.hbm.xml"/>
<mapping resource="lib/driver/mappings/UserRole.hbm.xml"/>
<mapping resource="lib/driver/mappings/UserLog.hbm.xml"/>
</session-factory>
</hibernate-configuration>
SessionFactoryUtil.java
package lib;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
import core.resources.statisticalResource;
public class SessionFactoryUtil {
//This class creates a session factory object by looking at the hibernate configuration (hibernate.cfg.xml)
private static SessionFactory sesFactory;
private static ServiceRegistry sesRegistry;
static Configuration cfg;
static{
try{
cfg= new Configuration().configure("lib/hibernateMaster.cfg.xml");
sesRegistry = new ServiceRegistryBuilder().applySettings(cfg.getProperties()).buildServiceRegistry();
sesFactory=cfg.buildSessionFactory(sesRegistry);
try{
Session session = SessionFactoryUtil.getSessionFactory().openSession();
Transaction tx = session.beginTransaction();
System.out.println("Connected to Master Database Server");
}
catch(Throwable ex){
cfg= new Configuration().configure("lib/hibernateSlave.cfg.xml");
sesRegistry = new ServiceRegistryBuilder().applySettings(cfg.getProperties()).buildServiceRegistry();
sesFactory=cfg.buildSessionFactory(sesRegistry);
System.out.println("Connected to Slave Database Server");
}
}
catch(Throwable ex){
System.out.println("Master & Slave Database Error.");
System.err.println("Initial SessionFactory Creation Failed"+ex);
throw new ExceptionInInitializerError(ex);
}
}
public static SessionFactory getSessionFactory() {
return sesFactory;
}
}
i dnt knw whether i have done something wrong on have done something wrong in SessionFactoryUtil.java .

Your problem is that you initialize your factory in a static way.
static{
...
}
That code is executed only once, when you start your application. That way when you shut down your master server hibernate stills asking for it.
You should initialize both configurations and use the main, if exists, or secondary in other case. You can do this in the getSessionFactory() method, that is executed each time the method is call, but not in an static initializer.

Error while Connecting postgres using Hibernate. - NullPointerException

Am getting below exception while connecting to postgresql,
INFO: HHH000046: Connection properties: {user=postgres, password=****}
Exception in thread "main" java.lang.NullPointerException
at org.hibernate.service.jdbc.connections.internal.DriverManagerConnectionProviderImpl.getConnection(DriverManagerConnectionProviderImpl.java:214)
at org.hibernate.engine.jdbc.internal.JdbcServicesImpl$ConnectionProviderJdbcConnectionAccess.obtainConnection(JdbcServicesImpl.java:242)
at org.hibernate.engine.jdbc.internal.JdbcServicesImpl.configure(JdbcServicesImpl.java:117)
at org.hibernate.service.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:75)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:159)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:131)
at org.hibernate.cfg.Configuration.buildTypeRegistrations(Configuration.java:1797)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1755)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1840)
at org.sri.hibernate.main.MainClass.main(MainClass.java:16)
Here is my hibernate.cfg.xml file.
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration SYSTEM "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory>
<property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
<property name="hibernate.connection.url">"jdbc:postgresql://localhost:5432/TestDataBase</property>
<property name="hibernate.connection.username">postgres</property>
<property name="hibernate.connection.password">1234</property>
<property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<property name="hibernate.hbm2ddl.auto">create-drop</property>
<mapping class="org.sri.hibernate.beans.UserDetails"/>
</session-factory>
</hibernate-configuration>
My connection URL, user Name and password are correct. Am trying to connect by using,
public static void main(String args[])
{
SessionFactory sf=new Configuration().configure().buildSessionFactory();
Session ss=sf.openSession();
Transaction tran=null;
UserDetails det= new UserDetails();
det.setDateOfBirth(new Date());
det.setUserName("SomeName");
try
{
tran=ss.beginTransaction();
ss.save(det);
tran.commit();
ss.close();
}catch(Exception e)
{
System.out.println(e.getMessage());
}
}
I use the same code to connect Oracle DB ( after changing the properties in xml ) it works fine, am I missing something specific to postgres ? Please help