hibernate 中的拦截器EmptyInterceptor接口功能
Interceptor接口提供了从会话(session)回调(callback)应用程序(application)的机制， 这种回调机制可以允许应用程序在持久化对象被保存、更新、删除或是加载之前，检查并（或）修改其 属性。一个可能的用途，就是用来跟踪审核(auditing)信息。例如：下面的这个拦截器，会在一个实现了 Auditable接口的对象被创建时自动地设置createTimestamp属性，并在实现了 Auditable接口的对象被更新时，同步更新lastUpdateTimestamp属性。
你可以直接实现Interceptor接口，也可以（最好）继承自EmptyInterceptor。
package org.hibernate.test;
import java.io.Serializable;
import java.util.Date;
import java.util.Iterator;
import org.hibernate.EmptyInterceptor;
import org.hibernate.Transaction;
import org.hibernate.type.Type;
public class AuditInterceptor extends EmptyInterceptor {
private int updates;
private int creates;
private int loads;
public void onDelete(Object entity,
Serializable id,
Object[] state,
String[] propertyNames,
Type[] types) {
// do nothing
}
public boolean onFlushDirty(Object entity,
Serializable id,
Object[] currentState,
Object[] previousState,
String[] propertyNames,
Type[] types) {
if ( entity instanceof Auditable ) {
updates++;
for ( int i=0; i < propertyNames.length; i++ ) {
if ( "lastUpdateTimestamp".equals( propertyNames[i] ) ) {
currentState[i] = new Date();
return true;
}
}
}
return false;
}
public boolean onLoad(Object entity,
Serializable id,
Object[] state,
String[] propertyNames,
Type[] types) {
if ( entity instanceof Auditable ) {
loads++;
}
return false;
}
public boolean onSave(Object entity,
Serializable id,
Object[] state,
String[] propertyNames,
Type[] types) {
if ( entity instanceof Auditable ) {
creates++;
for ( int i=0; i<propertyNames.length; i++ ) {
if ( "createTimestamp".equals( propertyNames[i] ) ) {
state[i] = new Date();
return true;
}
}
}
return false;
}
public void afterTransactionCompletion(Transaction tx) {
if ( tx.wasCommitted() ) {
System.out.println("Creations: " + creates + ", Updates: " + updates, "Loads: " + loads);
}
updates=0;
creates=0;
loads=0;
}
}
拦截器可以有两种:Session范围内的，和SessionFactory范围内的。
当使用某个重载的SessionFactory.openSession()使用Interceptor作为参数调用打开一个session的时候，就指定了Session范围内的拦截器。
Session session = sf.openSession( new AuditInterceptor() );
或在配置文件中加:
<bean id="sessionFactory" class="cn.sh.cares.framework.spring.annotationSessionFactoryBean">
<property name="dataSource" ref="ppcDataSource"/>
<!--<property name="lobHandler" ref="lobHandler"/>-->
<property name="annotatedClassesLocations">
<list>
<value>classpath*:</value>
</list>
</property>
<property name="hbmLocations">
<list>
<value>classpath*:</value>
</list>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">cn.sh.cares.framework.dao.hibernate.OracleDialect</prop>
<prop key="hibernate.format_sql">true</prop>
<prop key="hibernate.show_sql">true</prop>
<prop key="hibernate.use_sql_comments">false</prop>
<prop key="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</prop>
<prop key="hibernate.cache.use_query_cache">true</prop>
<prop key="hibernate.cache.use_second_level_cache">true</prop>
<prop key="hibernate.jdbc.batch_size">20</prop>
<prop key="hibernate.jdbc.fetch_size">20</prop>
</props>
</property>
<property name="entityInterceptor">
<bean id ="auditInterceptor" class="cn.sh.cares.framework.dao.hibernate.AuditInterceptor" />
</property>