Hibernate Detailed Tutorial
I. Build Hibernate environment
1.Create the hibernate.cfg.xml configuration file in the src directory
PS:documents of You can't change your name.！
<?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>
<!-- configure the database setting -->
<property name="connection.username">root</property>
<property name="connection.password">1234</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost:3306/test</property>
<!-- configure the hibernate setting -->
<!-- transaction is supported by org.hibernate.dialect.MySQL5InnoDBDialect -->
<property name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
<!-- show sql in the console -->
<property name="show_sql">true</property>
<!-- create and update the database automaticlly -->
<property name="hbm2ddl.auto">update</property>
<!-- javax.persistence.validation.mode The default isauto of， It means that if you don't set it up it will automatically go to yourclasspath Find one below
bean-validation** packet， But I can't find it.， consequentlybeanvalitionFactory mistakes -->
<property name="javax.persistence.validation.mode">none</property>
</session-factory>
</hibernate-configuration>2. Writing entity classes, using the Person class as an example
package test.Hibernate.model;
import java.util.HashSet;
import java.util.Set;
public class Person {
@Override
public String toString() {
return "Person [id=" + id + ", name=" + name + "]";
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Set<String> getAddress() {
return address;
}
public void setAddress(Set<String> address) {
this.address = address;
}
private int id;
private String name;
private Set<String> address = new HashSet<String>();
}3.Write Person.hbm.xml entity class configuration file
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!--
Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping package="test.Hibernate.model">
<class name="Person" table="person">
<id column="id" name="id" type="int">
<generator class="native"></generator>
</id>
<property name="name" column="name" length="50" type="string"></property>
<set name="address" table="address">
<key column="personId"></key>
<element column="address" type="string" length="50"></element>
</set>
</class>
</hibernate-mapping>4.Add mapping information to hibernate.cfg.xml
<mapping resource="test/Hibernate/model/Person.hbm.xml" />
5.Using MyEclipse to generate SessionFactory
package test.Hibernate.SessionFactory;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
/**
* 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 SessionFactory {
/**
* 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 final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
private static org.hibernate.SessionFactory sessionFactory;
private static Configuration configuration = new Configuration();
private static ServiceRegistry serviceRegistry;
static {
try {
configuration.configure();
serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
} catch (Exception e) {
System.err.println("%%%% Error Creating SessionFactory %%%%");
e.printStackTrace();
}
}
private SessionFactory() {
}
/**
* 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.configure();
serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
sessionFactory = configuration.buildSessionFactory(serviceRegistry);
} 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 hibernate configuration
*
*/
public static Configuration getConfiguration() {
return configuration;
}
}6.Writing test classes
package test.Hibernate.dao;
import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.Test;
import test.Hibernate.SessionFactory.SessionFactory;
import test.Hibernate.model.Person;
public class PersonDao {
@Test
public void add(){
Session session = SessionFactory.getSession();
Transaction tr = session.beginTransaction();
//----------------------------------------------
Person p = new Person();
p.setName("test");
p.getAddress().add("firstAddr");
p.getAddress().add("secondAddr");
p.getAddress().add("thirdAddr");
p.getAddress().add("fourthAddr");
session.save(p);
//----------------------------------------------
tr.commit();
SessionFactory.closeSession();
}
@Test
public void get(){
Session session = SessionFactory.getSession();
Transaction tr = session.beginTransaction();
//----------------------------------------------
Person p = (Person)session.get(Person.class, 2);
System.out.println(p);
//----------------------------------------------
tr.commit();
SessionFactory.closeSession();
}
}II. Primary key generation strategy
identity : Use the database's auto-growth strategy, not all databases support it, for example oracle does not.
sequence： (located) atDB2，PostgreSQL，Oracle，SAPDB，McKoi Using sequences in（sequence） in useOracle This one can be used when the database。
hilo :Generate primary key values using the high-low algorithm. Only one additional table is needed and all data is supported.
native: Based on the underlying database of Ability selectionidentity、sequence perhapshilo in of an。
assigned : Specify the primary key value manually.
uuid : The UUID is automatically generated by Hibernate and assigned as the primary key value.
Three, Hibernate mapping relationship configuration
1. one-to-one mapping（ Using primary key associations as an example）User together withIdCard（ Foreign keyed side） ofXML configure：
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!--
Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping package="test.Hibernate.model">
<class name="User" table="user">
<id name="id" type="int" column="id">
<generator class="native"></generator>
</id>
<property name="name" type="string" column="name"/>
<set name="address" table="address">
<key column="userId"></key>
<element column="address" type="string"></element>
</set>
<one-to-one name="idCard" class="IdCard" cascade="all"></one-to-one>
</class>
</hibernate-mapping><?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!--
Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping package="test.Hibernate.model">
<class name="IdCard" table="idCard">
<id name="id" type="int" column="id">
<generator class="foreign">
<param name="property">user</param>
</generator>
</id>
<property name="number" type="string" column="number"/>
<one-to-one name="user" class="User" constrained="true"></one-to-one>
</class>
</hibernate-mapping>2.One to many, many to one (using Father and Children as an example)
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="test.Hibernate.model">
<class name="Father" table="father">
<id name="id" type="int" column="id" >
<generator class="native"></generator>
</id>
<property name="name" type="string" column="name"/>
<set name="children" cascade="all">
<key column="fatherId"></key>
<one-to-many class="Children"/>
</set>
</class>
</hibernate-mapping><?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="test.Hibernate.model">
<class name="Children" table="children">
<id name="id" type="int" column="id" >
<generator class="native"></generator>
</id>
<property name="name" type="string" column="name"/>
<many-to-one name="father" class="Father" column="fatherId"></many-to-one>
</class>
</hibernate-mapping>3.Many-to-many (Student and Teacher as an example)
PS: Set sets with one side should be marked inverse=true (more on that later)
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!--
Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping package="test.Hibernate.model">
<class name="Student" table="student">
<id name="id" type="int" column="id">
<generator class="native"></generator>
</id>
<property name="name" type="string" column="name" length="20"/>
<set name="teachers" table="student_teacher" inverse="false" >
<key column="studentId"></key>
<many-to-many class="Teacher" column="teacherId"></many-to-many>
</set>
</class>
</hibernate-mapping><?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<!--
Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping package="test.Hibernate.model">
<class name="Teacher" table="teacher">
<id name="id" type="int" column="id">
<generator class="native"></generator>
</id>
<property name="name" column="name" type="string" length="20"></property>
<set name="students" table="student_teacher" inverse="true" cascade="all">
<key column="teacherId"></key>
<many-to-many class="Student" column="studentId"></many-to-many>
</set>
</class>
</hibernate-mapping>IV. The difference between inverse and cascade (personal summary, please correct me if I'm wrong)
1.inverse=false on a one-to-many delete sets the child's foreign key to null, then deletes the father, and the child is not deleted, while casecade=all on a one-to-many delete sets the child's foreign key to null, then deletes the father, then deletes the child
2.manytomany of When maintained by one party， consequently One party is to setinverse=false， neverthelessinverse=true of Direct deletion by the other party will result in an error， This time you can usecasecade Complete cascade deletion
3.inverse=false For use onlyset etc. set attributes， (located) atonetoone The relationship can be used incasecade Complete cascade deletion
V. Using C3P0 connection pools
1. Additional import required3 sizejar packet
2.Add C3P0 configuration information to hibernate.cfg.xml
<!-- C3P0 Connection pool settings-->
<!-- usec3p0 connection pool Configuring the connection pool provides of suppliers-->
<property name="connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider</property>
<!-- Available in the connection pool of Database connection of Minimum number -->
<property name="c3p0.min_size">5</property>
<!-- All database connections in the connection pool of maximum number -->
<property name="c3p0.max_size">20</property>
<!-- Setting up a database connection of expiration date, in seconds,
If the connection pool in of A database connection is idle of More time thantimeout times, will be cleared from the connection pool -->
<property name="c3p0.timeout">120</property>
<!-- each3000 Seconds to check all connections in the pool of idle connection in seconds-->
<property name="c3p0.idle_test_period">3000</property>VI. HQL Statements
@Test
public void HQLSearch(){
Session session = SessionFactory.getSession();
Transaction tr = session.beginTransaction();
//-----------------------------------------
//common search with where
// String hql= "select e.id,e.name from User e where e.id>=5 and e.id<=9";
// Query query = session.createQuery(hql);
// List list = query.list();
// for(Object o : list){
// System.out.println(Arrays.toString((Object[])o));
// }
//paging search
// String hql= "select e.id,e.name from User e";
// Query query = session.createQuery(hql);
// query.setFirstResult(0);
// query.setMaxResults(10);
// List list = query.list();
// for(Object o : list){
// System.out.println(Arrays.toString((Object[])o));
// }
//search with parameters
// String hql= "select e.id,e.name from User e where id>=? and id<=?";
// Query query = session.createQuery(hql)
// .setParameter(0, 1)
// .setParameter(1, 3);
// List list = query.list();
// for(Object o : list){
// System.out.println(Arrays.toString((Object[])o));
// }
//search with parameters whose type is collection
// String hql= "select e.id,e.name from User e where id in (:ids)";
// Query query = session.createQuery(hql)
// .setParameterList("ids",new Object[]{1,2,3,8} );
// List list = query.list();
// for(Object o : list){
// System.out.println(Arrays.toString((Object[])o));
// }
//-----------------------------------------
tr.commit();
SessionFactory.closeSession();
}VII. DML statements
@Test
public void DML(){
Session session = SessionFactory.getSession();
Transaction tr = session.beginTransaction();
//-----------------------------------------
User u = (User)session.get(User.class, 11);
String sql = "update User set name=? where id>?";
int result = session.createQuery(sql)
.setParameter(0, "updated")
.setParameter(1, 10)
.executeUpdate();
System.out.println("count of update:"+result);
//the object's status in session was not updated when the object in database have been changed,so if you want
//to get the updated object in session,you should use method "refresh".
session.refresh(u);
System.out.println(u);
//-----------------------------------------
tr.commit();
SessionFactory.closeSession();
}Eight, open the second level of cache
1. The following jar packages need to be imported
2.Add the following configuration to hibernate.cfg.xml
<!-- Use of L2 cache， Default is unopened of。 -->
<!-- Specify that you want to use the of buffer memory of provider (company)， This also opens the secondary cache-->
<property name="hibernate.cache.use_second_level_cache">true</property>
<property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.EhCacheRegionFactory</property>
<!-- Enabling the use of query caching -->
<property name="cache.use_query_cache">true</property>
<!-- Specify that you want to use the L2 cache of physical category -->
<class-cache usage="read-write" class="test.Hibernate.model.Person" />