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SchemaExporter tool to create two sample tables. Here I shall explore the tool in more detail.The tool can be enabled by setting the below property in our cfg file:
<property name="hibernate.hbm2ddl.auto">create-drop</property>
Or if we are using hibernate.properties
hibernate.hbm2ddl.auto=create-drop
hibernate.hbm2ddl.auto Automatically validates or exports schema DDL to the database when the SessionFactory is created. With create-drop, the database schema will be dropped when the SessionFactory is closed explicitly.
e.g. validate | update | create | create-drop
So the list of possible options are,
- validate: validate the schema, makes no changes to the database.
- update: update the schema.
- create: creates the schema, destroying previous data.
- create-drop: drop the schema at the end of the session.
I shall run the tool on our previous tables (Item and Shelf) for the available different configurations.
Java Code:
public static void main(String[] args) {
Configuration configuration = new Configuration();
configuration = configuration.configure();
sessionFactory = configuration.buildSessionFactory();
}
Here is the example code to test hbm2ddl functionality :
This is hibernate.cfg.xml file for connecting the postgreSQL database.
<?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.connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
hibernate word is optional <property name="connection.url">jdbc:oracle:thin:@localhost:1521:ORCL</property>
<property name="hibernate.connection.username">kcv</property> <property name="hibernate.connection.password">kcv</property>
<property name="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</property>
<property name="show_sql">true</property> <mapping resource="Employee.hbm.xml"/>
</session-factory> -->
<session-factory>
<property name="hibernate.current_session_context_class">thread</property>
<property name="hbm2ddl.auto">create</property>
<property name="dialect">org.hibernate.dialect.PostgreSQLDialect</property>
<property name="connection.url">jdbc:postgresql://localhost:5432/hibernate</property>
<property name="connection.username">postgres</property>
<property name="connection.password">password</property>
<property name="connection.driver_class">org.postgresql.Driver</property>
<property name="show_sql">true</property>
<property name="format_sql">true</property>
<property name="use_sql_comments">true</property>
<mapping resource="EmployeeBean.hbm.xml" />
</session-factory>
</hibernate-configuration>
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This is EmployeeBean.hbm.xml mapping file for map the Entity(POJO) class to columns.
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="com.cv.hibernate.hbm2ddl.auto.model">
<class name="EmployeeBean" table="EMPLOYEE_HBM_AUTO">
<id name="id" type="java.lang.Long">
<column name="EID" length="8" />
<generator class="assigned"></generator>
</id>
<property name="firstName" type="java.lang.String">
<column name="FIRSTNAME" length="29" not-null="true" />
</property>
<property name="lastName" type="java.lang.String">
<column name="LASTNAME" length="29" not-null="true" />
</property>
<property name="email" type="java.lang.String">
<column name="EMAIL" length="39" not-null="true" />
</property>
</class>
</hibernate-mapping>
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This is HBM2DDLAutoCreate.java main class having the application business logic.
package com.cv.hibernate.hbm2ddl.auto;
import org.apache.log4j.Logger;
import org.hibernate.Session;
import com.cv.hibernate.hbm2ddl.auto.model.EmployeeBean;
import com.cv.hibernate.hbm2ddl.auto.util.HibernateUtil;
/**
* @author Chandra Vardhan
*/
public class HBM2DDLAutoCreate {
private final static Logger logger = Logger.getLogger(HBM2DDLAutoCreate.class);
public static void main(String[] args) throws Exception {
Session session = HibernateUtil.getSession();
EmployeeBean eb = new EmployeeBean();
eb.setId(new Long(101));
eb.setFirstName("chandra");
eb.setLastName("kodam");
eb.setEmail("meetkodam@gmail.com");
session.beginTransaction();
Long io = (Long) session.save(eb);
logger.info("Saved entity/object id : " + io);
session.getTransaction().commit();
HibernateUtil.closeSession();
}
} |
This is HBM2DDLAutoCreateDrop.java main class having the application business logic.
package com.cv.hibernate.hbm2ddl.auto;
import org.apache.log4j.Logger;
import org.hibernate.Session;
import com.cv.hibernate.hbm2ddl.auto.model.EmployeeBean;
import com.cv.hibernate.hbm2ddl.auto.util.HibernateUtil;
/**
* @author Chandra Vardhan
*/
public class HBM2DDLAutoCreateDrop {
private final static Logger logger = Logger.getLogger(HBM2DDLAutoCreateDrop.class);
public static void main(String[] args) throws Exception {
Session session = HibernateUtil.getSession();
EmployeeBean eb = new EmployeeBean();
eb.setId(new Long(111));
eb.setFirstName("chandra");
eb.setLastName("kodam");
eb.setEmail("meetkodam@gmail.com");
session.beginTransaction();
Long io = (Long) session.save(eb);
logger.info("Saved entity/object id : " + io);
session.getTransaction().commit();
Thread.sleep(20000);
HibernateUtil.closeSession();
}
} |
This is HBM2DDLAutoUpdate.java main class having the application business logic.
package com.cv.hibernate.hbm2ddl.auto;
import org.apache.log4j.Logger;
import org.hibernate.Session;
import org.hibernate.Transaction;
import com.cv.hibernate.hbm2ddl.auto.model.EmployeeBean;
import com.cv.hibernate.hbm2ddl.auto.util.HibernateUtil;
/**
* @author Chandra Vardhan
*/
public class HBM2DDLAutoUpdate {
private final static Logger logger = Logger.getLogger(HBM2DDLAutoUpdate.class);
public static void main(String[] args) throws Exception {
Session session = HibernateUtil.getSession();
EmployeeBean eb = new EmployeeBean();
eb.setId(new Long(101));
eb.setFirstName("chandra");
eb.setLastName("kodam");
eb.setEmail("meetkodam@gmail.com");
session.beginTransaction();
Long io = (Long) session.save(eb);
logger.info("Saved entity/object id : " + io);
session.getTransaction().commit();
HibernateUtil.closeSession();
}
} |
This is HBM2DDLAutoValidate.java main class having the application business logic.
package com.cv.hibernate.hbm2ddl.auto;
import org.apache.log4j.Logger;
import org.hibernate.Session;
import org.hibernate.Transaction;
import com.cv.hibernate.hbm2ddl.auto.model.EmployeeBean;
import com.cv.hibernate.hbm2ddl.auto.util.HibernateUtil;
/**
* @author Chandra Vardhan
*/
public class HBM2DDLAutoValidate {
private final static Logger logger = Logger.getLogger(HBM2DDLAutoValidate.class);
public static void main(String[] args) throws Exception {
Session session = HibernateUtil.getSession();
EmployeeBean eb = new EmployeeBean();
eb.setId(new Long(102));
eb.setFirstName("chandra");
eb.setLastName("kodam");
eb.setEmail("meetkodam@gmail.com");
session.beginTransaction();
Long io = (Long) session.save(eb);
logger.info("Saved entity/object id : " + io);
session.getTransaction().commit();
HibernateUtil.closeSession();
}
} |
This is EmployeeBean.java Entity(POJO) class having the fields needs to be configured in mapping file.
package com.cv.hibernate.hbm2ddl.auto.model;
/**
* @author Chandra Vardhan
*/
public class EmployeeBean {
private long id;
private String firstName;
private String lastName;
private String email;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getFirstName() {
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
} |
This is HibernateUtil.java utility class for getting the database connection.
package com.cv.hibernate.hbm2ddl.auto.util;
import java.util.Properties;
import org.apache.log4j.Logger;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
import com.cv.hibernate.hbm2ddl.auto.model.EmployeeBean;
/**
* Configures and provides access to Hibernate sessions, tied to the current
* thread of execution. Follows the Thread Local Session pattern, see
* {@link http://hibernate.org/42.html }.
*/
public class HibernateUtil {
private final static Logger logger = Logger.getLogger(HibernateUtil.class);
/**
* Location of hibernate.cfg.xml file. Location should be on the classpath
* as Hibernate uses #resourceAsStream style lookup for its configuration
* file. The default classpath location of the hibernate config file is in
* the default package. Use #setConfigFile() to update the location of the
* configuration file for the current session.
*/
private static String HBM2DDL_AUTO = "";
static {
String className = Thread.currentThread().getStackTrace()[2].getClassName();
if (className != null) {
if (className.endsWith("Create")) {
HBM2DDL_AUTO = "create";
} else if (className.endsWith("CreateDrop")) {
HBM2DDL_AUTO = "create-drop";
} else if (className.endsWith("Update")) {
HBM2DDL_AUTO = "update";
} else {
HBM2DDL_AUTO = "validate";
}
}
}
private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";
private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
private static Configuration configuration = new Configuration();
private static SessionFactory sessionFactory;
static {
try {
configuration = configuration.configure(CONFIG_FILE_LOCATION);
Properties properties = configuration.getProperties();
properties.setProperty("hibernate.hbm2ddl.auto", HBM2DDL_AUTO);
configuration.setProperties(properties);
StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().applySettings(configuration.getProperties());
sessionFactory = configuration.buildSessionFactory(builder.build());
logger.info("%%%% Connection successful %%%%");
} catch (Exception e) {
logger.error("%%%% Error Creating SessionFactory %%%%");
e.printStackTrace();
}
}
private HibernateUtil() {
}
/**
* Returns the ThreadLocal Session instance. Lazy initialize the
* <code>SessionFactory</code> if needed.
*
* @return Session
* @throws HibernateException
*/
public static Session getSession() throws HibernateException {
Session session = (Session) threadLocal.get();
if (session == null || !session.isOpen()) {
if (sessionFactory == null) {
rebuildSessionFactory();
}
session = (sessionFactory != null) ? sessionFactory.openSession() : null;
threadLocal.set(session);
}
return session;
}
/**
* Rebuild hibernate session factory
*
*/
public static void rebuildSessionFactory() {
try {
configuration = configuration.configure(CONFIG_FILE_LOCATION);
StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder()
.applySettings(configuration.getProperties());
sessionFactory = configuration.buildSessionFactory(builder.build());
logger.info("%%%% Connection successful %%%%");
} catch (Exception e) {
logger.error("%%%% Error Creating SessionFactory %%%%");
e.printStackTrace();
}
}
/**
* Close the single hibernate session instance.
*
* @throws HibernateException
*/
public static void closeSession() throws HibernateException {
Session session = (Session) threadLocal.get();
threadLocal.set(null);
if (session != null) {
session.close();
System.exit(0);
}
}
/**
* return session factory
*
*/
public static SessionFactory getSessionFactory() {
return sessionFactory;
}
/**
* return hibernate configuration
*
*/
public static Configuration getConfiguration() {
return configuration;
}
public static void saveOrUpdate() {
Session ses = getSession();
EmployeeBean eb = new EmployeeBean();
eb.setId(new Long(101));
eb.setFirstName("chandra");
eb.setLastName("vardhan");
eb.setEmail("meetkodam@gmail.com");
Transaction tx = ses.beginTransaction();
ses.saveOrUpdate(eb);
logger.info("Saved successful...");
tx.commit();
ses.close();
}
} |
This is log4j.properties file having the entries for logging the information into the console/file.
#By default enabling Console appender
# Root logger option
log4j.rootLogger=INFO, stdout
# Redirect log messages to console
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%-5p [%c]:%L -->> %m%n
# Redirect log messages to a log file
#log4j.appender.file=org.apache.log4j.RollingFileAppender
#log4j.appender.file.File=C:\\servlet-application.log
#log4j.appender.file.MaxFileSize=5MB
#log4j.appender.file.MaxBackupIndex=10
#log4j.appender.file.layout=org.apache.log4j.PatternLayout
#log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n
|
This is pom.xml file having the entries of dependency jars and information to build the application .
| <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.cv.hibernate.auto</groupId>
<artifactId>Hibernate-HBM2DDL-Auto-Property</artifactId>
<version>1.0</version>
<dependencies>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>4.3.5.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-c3p0</artifactId>
<version>4.3.5.Final</version>
</dependency>
<dependency>
<artifactId>hibernate-core</artifactId>
<groupId>org.hibernate</groupId>
<version>4.3.5.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>4.2.0.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate.common</groupId>
<artifactId>hibernate-commons-annotations</artifactId>
<version>4.0.4.Final</version>
</dependency>
<dependency>
<groupId>org.hibernate.javax.persistence</groupId>
<artifactId>hibernate-jpa-2.0-api</artifactId>
<version>1.0.1.Final</version>
</dependency>
<dependency>
<groupId>javax.validation</groupId>
<artifactId>validation-api</artifactId>
<version>1.0.0.GA</version>
provided
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.6.4</version>
</dependency>
<dependency>
<groupId>org.jboss.logging</groupId>
<artifactId>jboss-logging</artifactId>
<version>3.1.0.CR2</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.6.4</version>
</dependency>
<dependency>
<groupId>postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>9.1-901.jdbc4</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-simple</artifactId>
<version>1.7.5</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.3</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
</project> |
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