Hibernate实战——事件机制中的拦截器

末蓝、 2021-07-25 01:53 374阅读 0赞

**一 配置**

<?xml version="1.0" encoding="GBK"?>
    
    <!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>
               
               <property  name="connection.driver_class">com.mysql.jdbc.Driver</property>
               
               <property  name="connection.url">jdbc:mysql://localhost/hibernate</property>
               
               <property name="connection.username">root</property>
               
               <property name="connection.password">32147</property>
               
               <property  name="hibernate.c3p0.max_size">200</property>
               
               <property name="hibernate.c3p0.min_size">2</property>
               
               <property  name="hibernate.c3p0.timeout">5000</property>
               
               <property  name="hibernate.c3p0.max_statements">100</property>
               <property  name="hibernate.c3p0.idle_test_period">3000</property>
               <property  name="hibernate.c3p0.acquire_increment">2</property>
               <property  name="hibernate.c3p0.validate">true</property>
               
               <property  name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
               
               <property name="hbm2ddl.auto">update</property>
               
               <property name="show_sql">true</property>
               
               <property name="hibernate.format_sql">true</property>
               
               <property  name="hibernate.current_session_context_class">thread</property>
               
               <mapping class="org.crazyit.app.domain.User"/>
         </session-factory>
    </hibernate-configuration>

**二 PO**

package org.crazyit.app.domain;
    
    import java.util.*;
    
    import javax.persistence.*;
    
    @Entity
    @Table(name="user_inf")
    
    public class User
    {
        @Id @Column(name="user_id")
        @GeneratedValue(strategy=GenerationType.IDENTITY)
        private Integer id;
        private String name;
        private int age;
        private String nationality;
    
        // 无参数的构造器
        public User()
        {
        }
        // 初始化全部成员变量的构造器
        public User(Integer id , String name , int age , String nationality)
        {
            this.id = id;
            this.name = name;
            this.age = age;
            this.nationality = nationality;
        }
    
        // id的setter和getter方法
        public void setId(Integer id)
        {
            this.id = id;
        }
        public Integer getId()
        {
            return this.id;
        }
    
        // name的setter和getter方法
        public void setName(String name)
        {
            this.name = name;
        }
        public String getName()
        {
            return this.name;
        }
    
        // age的setter和getter方法
        public void setAge(int age)
        {
            this.age = age;
        }
        public int getAge()
        {
            return this.age;
        }
    
        // nationality的setter和getter方法
        public void setNationality(String nationality)
        {
            this.nationality = nationality;
        }
        public String getNationality()
        {
            return this.nationality;
        }
    
    }

**三 拦截器**

package org.crazyit.common.hibernate.interceptor;
    
    import java.util.*;
    import java.io.*;
    
    import org.hibernate.*;
    import org.hibernate.type.Type;
    
    
    // 通常采用采用继承EmptyInterceptor来实现拦截器
    public class MyInterceptor extends EmptyInterceptor
    {
        // 记录修改次数
        private int updates;
        // 记录创建次数
        private int creates;
    
        // 当删除实体时，onDelete()方法将被调用
        public void onDelete(Object entity , Serializable id ,
            Object[] state , String[] propertyNames , Type[] types)
        {
            // do nothing
        }
    
        // 当把持久化实体的状态同步到数据库时，onFlushDirty()方法被调用
        public boolean onFlushDirty(Object entity , Serializable id ,
            Object[] currentState, Object[] previousState,
            String[] propertyNames, Type[] types)
        {
            // 每同步一次，修改的累加器加1
            updates++;
            for ( int i = 0; i < propertyNames.length; i++ )
            {
                System.out.println("-------更新---------------"+ propertyNames[i] );
                if ( "lastUpdateTimestamp".equals( propertyNames[i] ) )
                {
                    currentState[i] = new Date();
                    return true;
                }
            }
            return false;
        }
    
        // 当加载持久化实体时，onLoad()方法被调用
        public boolean onLoad(Object entity , Serializable id ,
            Object[] state,String[] propertyNames,Type[] types)
        {
            for ( int i = 0; i < propertyNames.length ; i++ )
            {
                System.out.println("++++++加载+++++++++++++"+ state[i] );
                if ( "name".equals( propertyNames[i] ) )
                {
                    // 输出被装载实体的name属性值
                    System.out.println( state[i] );
                    return true;
                }
            }
            return false;
        }
    
        // 保存持久化实例时候，调用该方法
        public boolean onSave(Object entity , Serializable id ,
            Object[] state,String[] propertyNames,Type[] types)
        {
            creates++;
            for ( int i = 0; i < propertyNames.length; i++ )
            {
                System.out.println("=============保存====================="+ propertyNames[i] );
                if ("createTimestamp".equals( propertyNames[i]))
                {
                    state[i] = new Date();
                    return true;
                }
            }
            return false;
        }
    
        // 持久化所做修改同步完成后，调用postFlush()方法
        public void postFlush(Iterator entities)
        {
            System.out.println("创建的次数： "
                + creates + ", 更新的次数： " + updates);
        }
    
        // 在同步持久化所做修改之前，调用preFlush方法
        public void preFlush(Iterator entities)
        {
            // do nothing
        }
    
        // 事务提交之前触发该方法
        public void beforeTransactionCompletion(Transaction tx)
        {
            System.out.println("事务即将结束");
        }
    
        // 事务提交之后触发该方法
        public void afterTransactionCompletion(Transaction tx)
        {
            System.out.println("事务已经结束");
        }
    }

**四 测试**

package lee;
    
    import org.hibernate.*;
    import org.hibernate.cfg.*;
    import org.hibernate.service.*;
    import org.hibernate.boot.registry.*;
    
    import java.util.*;
    
    import org.crazyit.app.domain.*;
    import org.crazyit.common.hibernate.interceptor.MyInterceptor;
    
    public class UserManager
    {
        static Configuration cfg = new Configuration()
            // 加载hibernate.cfg.xml配置文件
            .configure()
            // 设置启用全局拦截器
            .setInterceptor(new MyInterceptor());
        // 以Configuration实例创建SessionFactory实例
        static ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
            .applySettings(cfg.getProperties()).build();
        static SessionFactory sf = cfg.buildSessionFactory(serviceRegistry);
        public static void main(String[] args)
        {
            UserManager mgr = new UserManager();
            mgr.testUser();
            sf.close();
        }
        private void testUser()
        {
            Session session = sf.getCurrentSession();
            Transaction tx = session.beginTransaction();
            // 创建一个User对象
            User u1 = new User();
            u1.setName("crazyit.org");
            u1.setAge(30);
            u1.setNationality("china");
            session.save(u1);
            User u = (User)session.load(User.class , 1);
            u.setName("疯狂Java联盟");
            tx.commit();
        }
    }

**五 测试结果**

=============保存=====================age
    =============保存=====================name
    =============保存=====================nationality
    Hibernate:
        insert
        into
            user_inf
            (age, name, nationality)
        values
            (?, ?, ?)
    Hibernate:
        select
            user0_.user_id as user_id1_0_0_,
            user0_.age as age2_0_0_,
            user0_.name as name3_0_0_,
            user0_.nationality as national4_0_0_
        from
            user_inf user0_
        where
            user0_.user_id=?
    ++++++加载+++++++++++++30
    ++++++加载+++++++++++++疯狂Java联盟
    疯狂Java联盟
    创建的次数： 1, 更新的次数： 0
    事务即将结束
    事务已经结束