Hiberante3.6的使用入門

1、Hibernate3.6的主要AIP組件

1.1 Configuration:用於配置並且啓動Hibernate框架

每個Hibernate配置文件對應一個Configuration對象。Hibernate通過Configuration實例的configure()方法讀取配置文件Hibernate.cfg.xml,在通過Configuration實例的buildSessionFactory()方法創建SessionFactory實例。

Configuration configuration=new Configuration().configure();

1.2 SessionFactory:會話工廠

一個SessionFactory實例對應一個數據源，即一個數據庫。

SessionFactory sessionFactory=configuration.buildSessionFactory();

1.3 Session:會話管理器，簡稱“會話”

一個Session實例完成一次會話，一次會話就是一次對數據庫的訪問。應用程序通過SessionFactory的openSession()方法或getCurrentSession()方法中獲得Session實例。

Session session=sessionFactroy.openSession();

1.4 Query：查詢組件

Query用於從數據庫中查詢對象，並控制執行查詢的過程。Query包裝了HQL查詢語句，HQL查詢語句是變面向對象的，它引用類名及類的屬性名，而不是應用表名及字段名。

通過Session實例的createQuery()方法創建Query實例，典型的語句爲：

Query query=session.createQuery(HQL語句);

1.5 Transaction:事務管理器

Transaction是Hibernate的數據庫事務管理器，它對底層的事務做了封裝，底層事務包括JDBC事務和JTA事務

try
{
    Transaction tran=session.beginTransaction();
    ...
    tran.commit();
}
catch(Exception e)
{
    e.printStackTrace();
    tran.rollback();
}

2、實例：學生Student和班級Clazz，雙向一對多關係

2.1 導入Hibernate必需jar包

2.2 Hibernate配置文件hibernate.cfg.xml的編寫

//放於/src目錄下

<?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>
     <!--jdbc驅動，此處使用的數據庫爲sqlserver-->
       <property name="hibernate.connection.driver_class">
          com.microsoft.sqlserver.jdbc.SQLServerDriver
       </property>

      <property name="hibernate.connection.password">
      </property>

       <property name="hibernate.connection.url">
           jdbc:sqlserver://127.0.0.1:1433;DatabaseName=數據庫名字
       </property>

      <property name="hibernate.connection.username">
           sa
       </property>

        <!--數據庫方言-->
      <property name="hibernate.dialect">
            org.hibernate.dialect.SQLServerDialect
     </property>

    <!--根據映射文件自動創建數據庫表格-->
     <property name="hbm2ddl.auto">
         create
     </property>

    <mapping resource="com/po/Student.hbm.xml" />            
    <mapping resource="com/po/Clazz.hbm.xml" />            

 </session-factory>


</hibernate-configuration>

2.3 創建session的公共類

//HibernateServiceProvider.java
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;

public class HibernateServiceProvider {
    private static SessionFactory sessionFactory=null;
    private static Configuration configuration=new Configuration();

    public HibernateServiceProvider()
    {
        this.initHibernate();
    }

    public synchronized void initHibernate()
    {
        if(sessionFactory==null)
        {
            try
            {
                configuration.configure();
                sessionFactory=configuration.buildSessionFactory();
            }
            catch(Exception e)
            {
                e.printStackTrace();
            }
        }
    }

    public void rebuildSessionFactory()
    {
        try
        {
            configuration.configure();
            sessionFactory=configuration.buildSessionFactory();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }

    public Session getSession()
    {
        if(sessionFactory==null)
        {
            this.rebuildSessionFactory();
        }
        Session session=sessionFactory.openSession();
        return session;
    }
    public void closeSession()
    {
        try
        {
            sessionFactory.close();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }
    }
}

2.4 PO類和映射文件的編寫

//Clazz.java
import java.util.HashSet;
import java.util.Set;

public class Clazz 
{
    private long claId;
    private String claName;
    private Set<Student> students=new HashSet<Student>();
    public long getClaId() {
        return claId;
    }
    public void setClaId(long claId) {
        this.claId = claId;
    }
    public String getClaName() {
        return claName;
    }
    public void setClaName(String claName) {
        this.claName = claName;
    }
    public Set<Student> getStudents() {
        return students;
    }
    public void setStudents(Set<Student> students) {
        this.students = students;
    }

}

//映射文件Clazz.hbm.xml，與po類放於同一目錄下
<?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">

<hibernate-mapping>
    <class name="com.po.Clazz" table="Clazz">
        <id name="claId" type="long">
            <column name="lClaId"/>
            <generator class="native"/>
        </id>
        <property name="claName" type="java.lang.String">
            <column name="vClaName" length="20"/>
        </property>
        <set name="students" table="Student" lazy="true" cascade="all">
            <key>
                <column name="lClaId"/>
            </key>
            <one-to-many class="com.po.Student"/>
        </set>
    </class>
</hibernate-mapping>

---

//Student.java
public class Student 
{
    private long stuId;
    private String stuName;
    private Clazz stuCla;

    public long getStuId() {
        return stuId;
    }
    public void setStuId(long stuId) {
        this.stuId = stuId;
    }
    public String getStuName() {
        return stuName;
    }
    public void setStuName(String stuName) {
        this.stuName = stuName;
    }
    public Clazz getStuCla() {
        return stuCla;
    }
    public void setStuCla(Clazz stuCla) {
        this.stuCla = stuCla;
    }
}

//映射文件Student.hbm.xml，與對應po類放於同一目錄下
<?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">

<hibernate-mapping>
    <class name="com.po.Student" table="Student">
        <id name="stuId" type="long">
            <column name="lStuId"/>
            <generator class="native"/>
        </id>
        <property name="stuName" type="java.lang.String">
            <column name="vStuName" length="20"/>
        </property>
        <many-to-one name="stuCla" class="com.po.Clazz" fetch="join" cascade="all">
            <column name="lClaId"/>
        </many-to-one>
    </class>
</hibernate-mapping>

2.5 Dao類的編寫

//ClazzDao.java
import org.hibernate.Session;
import org.hibernate.Transaction;

import com.po.Clazz;

public class ClazzDao 
{
    HibernateServiceProvider hsProvider=new HibernateServiceProvider();

    public boolean addClass(Clazz clazz)
    {
        boolean flag=false;
        Session session=hsProvider.getSession();
        Transaction trans=null;
        try
        {
            trans=session.beginTransaction();
            session.save(clazz);
            trans.commit();
            flag=true;
        }
        catch(Exception e)
        {
            e.printStackTrace();
            trans.rollback();
        }
        return flag;
    }
}

---

省略其他Dao類