1. Simple Example <?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"> <!-- Generated by MyEclipse Hibernate Tools. -->
<hibernate-configuration> <session-factory> <property name="connection.username">username</property> <property name="connection.url"> jdbc:oracle:thin:username/password@localhost:1521/XE </property> <property name="dialect"> org.hibernate.dialect.Oracle9Dialect </property> <property name="myeclipse.connection.profile">MyDriver</property> <property name="connection.password">password</property> <property name="connection.driver_class"> oracle.jdbc.driver.OracleDriver</property> <mapping resource="./Simple.hbm.xml" /> </session-factory> </hibernate-configuration> Simple.hbm.xml : <?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <!--
Mapping file autogenerated by MyEclipse Persistence Tools -->
<hibernate-mapping>
<class name="Simple" table="SIMPLE" schema="USERNAME"> <id name="id" type="java.lang.Long">
<column name="ID" precision="2" scale="0" /> <generator class="assigned" />
</id>
<property name="name" type="java.lang.String"> <column name="NAME" length="21" />
</class> </hibernate-mapping> Client class import org.hibernate.*; import org.hibernate.cfg.*; import org.hibernate.transaction.*; public class mainSimple {
public mainSimple() {
// TODO Auto-generated constructor stub }
/**
* @param args */
public static void main(String[] args) { // TODO Auto-generated method stub SessionFactory sf = new Configuration().configure(). buildSessionFactory();
Session ses = sf.openSession();
Transaction tx = ses.beginTransaction(); Simple sob=new Simple();
Sob.setId(21); Sob.setName(“LCBK Raju”); Ses.save(sob); Tx.close(); Ses.close(); } }
2. Create session factory: a.
SessionFactory sessions = new Configuration() .addResource("hello/Message.hbm.xml") .setProperties( System.getProperties() ) .buildSessionFactory();
b.
SessionFactory sessions = new Configuration() .addClass(org.hibernate.auction.model.Item.class) .addClass(org.hibernate.auction.model.Category.class) .addClass(org.hibernate.auction.model.Bid.class)
.setProperties( System.getProperties() ) .buildSessionFactory();
c. addjar
d. SessionFactory ses=new
Configuration().configure(“/aaa/bbb.xml”)…. e. General Way(hibernate.config.xml as config file)
SessionFactory ses=new
Configuration().configure().buildsessionFactory(); 3.c3po connection pooling settings
hibernate.connection.driver_class = oracle.jdbc.driver.OracleDriver hibernate.connection.url = jdbc:oracle:thin:username/password@localhost:1521/XE hibernate.connection.username = auctionuser hibernate.connection.password = secret hibernate.dialect = net.sf.hibernate.dialect.PostgreSQLDialect hibernate.c3p0.min_size=5 hibernate.c3p0.max_size=20 hibernate.c3p0.timeout=300 hibernate.c3p0.max_statements=50 hibernate.c3p0.idle_test_period=3000
4. Container managed hibernate.properties
hibernate.connection.datasource = java:/comp/env/jdbc/AuctionDB hibernate.transaction.factory_class = \ net.sf.hibernate.transaction.JTATransactionFactory hibernate.transaction.manager_lookup_class = \ net.sf.hibernate.transaction.JBossTransactionManagerLookup hibernate.dialect = net.sf.hibernate.dialect.PostgreSQLDialect
5. <property name="show_sql">true</property>// logging all generated SQL to console
6.Session Factory Class example a. package src2; import org.hibernate.HibernateException; import org.hibernate.Session; import org.hibernate.cfg.Configuration; /**
* 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 HibernateSessionFactory { /**
* 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 CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";
private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
private static Configuration configuration = new Configuration(); private static org.hibernate.SessionFactory sessionFactory;
private static String configFile = CONFIG_FILE_LOCATION; static { try { configuration.configure(configFile); sessionFactory = configuration.buildSessionFactory(); } catch (Exception e) { System.err
.println("%%%% Error Creating SessionFactory %%%%"); e.printStackTrace(); } } private HibernateSessionFactory() { } /**
* 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 (sessionFactory == null) { rebuildSessionFactory(); }
session = (sessionFactory != null) ? sessionFactory.openSession() : null; threadLocal.set(session); } return session; } /**
* Rebuild hibernate session factory *
*/
public static void rebuildSessionFactory() { try { configuration.configure(configFile); sessionFactory = configuration.buildSessionFactory(); } catch (Exception e) { System.err
.println("%%%% 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(); } } /**
* return session factory *
*/
public static org.hibernate.SessionFactory getSessionFactory() {
return sessionFactory; }
/**
* return session factory *
* session factory will be rebuilded in the next call */
public static void setConfigFile(String configFile) { HibernateSessionFactory.configFile = configFile; sessionFactory = null;
} /**
* return hibernate configuration *
*/
public static Configuration getConfiguration() { return configuration;
} }
b. Get Session Factory
Session ses=HibernateSessionfactory.getSession(); 8. Hibernate uses reflection in mappings
a.
the following mappings are equivalent:
<property name="description" column="DESCRIPTION" type="string"/>
<property name="description" column="DESCRIPTION"/>
b. u can omit column if pojo property name column name are same.
<property name=”id”/> c.
<property name="initialPrice" column="INITIAL_PRICE" not-null="true"/>
d. derived properties
formula="TOTAL + TAX_RATE * TOTAL" type="big_decimal"/>
e. U don’t required POJO <property name="name" column="NAME" type="string" access="field"/> f. <property name="name"
column="NAME" type="string" insert="false" update="false"/> g. class level setting
<class name="org.hibernate.auction.model.User" dynamic-insert="true" dynamic-update="true"> ...
</class> h.
If the complete class is immutable, set the immutable="false" in the class mapping
i. Quoted properties
<property name="description" column="`Item Description`"/> j. Naming Strategy ---- Add Notes
k. Schema 1.<hibernate-mapping> <class name="org.hibernate.auction.model.Category" table="CATEGORY" schema="AUCTION"> ... </class> </hibernate-mapping> 2. <hibernate-mapping default-schema="AUCTION"> .. </hibernate-mapping> L. <hibernate-mapping package="org.hibernate.auction.model"> <class name="Category" table="CATEGORY"> 9.
a. Hibernate exposes database identity to the application in two ways:
■ The value of the identifier property of a persistent instance ■ The value returned by Session.getIdentifier(Object o)
b.
Choosing Primary Key
XXX: assigned, native, identity, hilo, sequence, increment, uuid.hex 10. An object of entity type have DB identity. An object of value type does not have DB identity.
11. Composition: Life cycle of part dependent on life cycle of the whole.
Hibernate uses term component for a user defined class that is persisted to same table as owning entity.
For an example User class(Entity type), Address Class(Value type) <class name=”user” table=”USER”>
<id name=”UserId” column=”uid”> <generator type=”assigned”/></id> <property……….
………>
<component name=”homeAdress” class=”address”> <property
name--- > </component> // reusing component
<component name=”offAdress” class=”address”> ………
………</component></class> Table would be
userId, username, off_street,off_fno, home_street, home_fno
(office address) (home address) components
For bi-directional composition we need to do
<component name=”homeAdress” class=”address”> <parent name=”user”/>//tell the parent
<property name--- > </component>
So we can call Adress.getUser() now. Limitations:
1. shared references are not possible because only user can acess it. 2. If u store a component with null values then hibernate returns a null component.
12. 3 different approaches to representing inheritance hierarchy. a. Table per class: No polymorphism,
Associations
Hibernate Associations are inherently unidirectional. ManyToOne: UnDirectional
public class Bid { ...
private Item item;
public void setItem(Item item) { this.item = item;
}
public Item getItem() { return item;
} ... }
Next, here’s the Hibernate mapping for this association: <class name="Bid" table="BID"> ... <many-to-one name="item" column="ITEM_ID" class="Item" not-null="true"/> </class>
This mapping is called a unidirectional many-to-one association. The column ITEM_ID
in the BID table is a foreign key to the primary key of the ITEM table. ManyToOne Bidirectional:
public class Item { ...
private Set bids = new HashSet(); public void setBids(Set bids) { this.bids = bids;
}
public Set getBids() { return bids;
}
public void addBid(Bid bid) { bid.setItem(this);
bids.add(bid); }
... }
Basic One to Many Mapping.
<class name="Item" table="ITEM"> ... <set name="bids"> <key column="ITEM_ID"/> <one-to-many class="Bid"/> </set> </class>