Hibernate详细教程-白红宇

一、搭建Hibernate环境

1.在src目录下创建hibernate.cfg.xml配置文件

PS:文件的名字不能改！


     
         
              
               
       
        root
               
       
        1234
               
       
        com.mysql.jdbc.Driver
               
       
        jdbc:mysql://localhost:3306/test
               
               
               
       
        org.hibernate.dialect.MySQL5InnoDBDialect
        
               
       
        true
        　　　　 
               
       
        update
                       
               
       
        none

2. 编写实体类，以Person类为例

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
     
       getAddress() {        return address;    }    public void setAddress(Set
      
        address) {        this.address = address;    }    private int id;    private String name;    private Set
       
         address = new HashSet
        
         ();      }

3.编写Person.hbm.xml实体类配置文件

4.在hibernate.cfg.xml中加入映射信息

5.使用MyEclipse生成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
     
       threadLocal = new ThreadLocal
      
       ();    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 
       SessionFactory 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.编写测试类

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();    }}

二、主键生成策略

identity：使用数据库的自动增长策略，不是所有数据库都支持，比如oracle就不支持。

sequence：在 DB2，PostgreSQL，Oracle，SAP DB，McKoi 中使用序列（sequence）在使用Oracle数据库时可以使用这一个。

hilo:使用高低位算法生成主键值。只需要一张额外表，所有的数据都支持。

native:根据底层数据库的能力选择 identity、sequence 或者 hilo中的一个。

assigned：手工指定主键值。

uuid：由Hibernate自动生成UUID并指定为主键值。

三、Hibernate映射关系配置

1.一对一映射（以主键关联作为示例）User与IdCard（有外键方）的XML配置：

2.一对多，多对一（以Father和Children为例）

3.多对多（以Student和Teacher为例）

PS:有一方的set集合要标明inverse=true（后面会讲）

四、inverse和cascade的区别（个人总结，有不对还望指正）

1.inverse=false在一对多删除时是把孩子的外键设置为null，然后删除父亲，孩子不删除，而casecade=all在一对多删除时是把孩子的外键设置为null，然后删除父亲，然后再删除孩子

2.many to many的时候由一方维护，所以一方要设置inverse=false，但是inverse=true的另一方直接删除会出错，这个时候可以用casecade完成级联删除

3.inverse=false只用于set等集合属性，在one to one关系中可以用casecade完成级联删除

五、使用C3P0连接池

1.需要额外导入3个jar包

2.在hibernate.cfg.xml中加入C3P0配置信息


             
             
     
      org.hibernate.connection.C3P0ConnectionProvider
             
             
     
      5
             
             
     
      20
             
             
     
      120
              
             
     
      3000

六、HQL语句

@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();    }

七、DML语句

@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();    }

八、开启二级缓存

1. 需要导入以下jar包

2.在hibernate.cfg.xml中加入以下配置


             
              
     
      true
               
     
      org.hibernate.cache.ehcache.EhCacheRegionFactory
             
             
     
      true