Hibernate二级缓存

1. 基本配置：
   pom.xml中引入与当前hibernate对应版本的hibernate-ehcache包

   <!-- hibernate缓存包 -->
   		<dependency>
   			<groupId>org.hibernate</groupId>
   			<artifactId>hibernate-ehcache</artifactId>
   			<version>${hibernate.version}</version>
   		</dependency>
   

2. 在hibernate.cfg.xml中开启二级缓存
   
   
     true
   
   org.hibernate.cache.ehcache.internal.EhcacheRegionFactory
   注：查看该 类的方法一般是到引入的包中找到EhcacheRegionFactory.class这个类
   
   
3. 根目录中创建ehcache.xml
   
   
   
    

   "1.0" encoding="UTF-8"?>  
   <ehcache>  
       
     <diskStore path="G:/ehcache/"/>  
     
      
     
     
       <defaultCache maxElementsInMemory="10000"   
                   eternal="false"  
                   timeToIdleSeconds="300"   
                   timeToLiveSeconds="600" 
                   overflowToDisk="true"/>  
       
      
      
      <cache name="testCache"  
                   eternal="false"  
                   maxElementsInMemory="100" 
                   timeToIdleSeconds="1200"  
                   timeToLiveSeconds="1200"  
                   overflowToDisk="false">  
     cache>   
   ehcache> 
   

4. 配置指定要使用二级缓存的方式有两种
   a) 在hibernate.cfg.xml中指定要使用二级缓存的类

   <!-- 类级二级缓存：指定哪些类要使用二级缓存 -->
     <class-cache usage="read-write" class="com.restfullDemo.model.User"/>
     <class-cache usage="read-write" class="com.restfullDemo.model.Department"/>
     <!-- 集合级二级缓存，指定哪个类中的集合属性使用二级缓级，前提是该属性的类必须已设置二级缓存中 -->
     <collection-cache usage="read-write" collection="com.restfullDemo.model.Department.users"/>
   

   b) 也可以在类的对应映射文件中时行配置
    

   类的二级缓存配置
   <class name="com.restfullDemo.model.User" table="t_user">
       <cache usage="read-write"/>
   ......
   </class>
   

   集合级的二级缓存配置
   <hibernate-mapping>
       <class name="com.restfullDemo.model.Department" table="t_department">
           <id name="id" type="int">
               <column name="id" />
               <generator class="assigned" />
           </id>
           <property name="name" type="java.lang.String">
               <column name="name" />
           </property>
           <set name="users" table="t_user" inverse="false" lazy="false" >
           <cache usage="read-write"/>
               <key>
                   <column name="dpt_id" />
               </key>
               <one-to-many class="com.restfullDemo.model.User" />
           </set>
       </class>
   </hibernate-mapping>
   

   
   实例：
    

   public class User {
   	private int id;
   	private String name;
   	private int age;
   	private Department dpt;
       setter、getter.....
   }
   

   public class Department {
   	private int id;
   	private String name;
   	private Set<User> users = new HashSet<User>();
   setter、getter......
   }
   

   hibernet.cfg.xml
    

   "1.0" encoding="UTF-8"?>
   hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
                                            "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
   <hibernate-configuration>
    <session-factory name="">
     <property name="hibernate.dialect">xxxxxproperty>
     <property name="hibernate.connection.driver_class">xxxxproperty>
     <property name="hibernate.connection.url">xxxxproperty>
     <property name="hibernate.connection.username">xxxxproperty>
     <property name="hibernate.connection.password">123456property>
     <property name="hibernate.show_sql">trueproperty>
     <property name="hibernate.format_sql">trueproperty>
     <property name="hibernate.hbm2ddl.auto">updateproperty>
     
     <property name="hibernate.cache.use_second_level_cache">trueproperty>
     <property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.internal.EhcacheRegionFactoryproperty>
     
     <mapping resource="com/restfullDemo/mappingResources/User.hbm.xml"/>
     <mapping resource="com/restfullDemo/mappingResources/Department.hbm.xml"/>
     
     <class-cache usage="read-write" class="com.restfullDemo.model.User"/>
     <class-cache usage="read-write" class="com.restfullDemo.model.Department"/>
     
     <collection-cache usage="read-write" collection="com.restfullDemo.model.Department.users"/>
    session-factory>
   hibernate-configuration>
   

   

查询缓存

查询缓存依赖于二级缓存，二级缓存没有开，查询缓存会失效，同理当设置完类级、集合集的二级缓存后，二级缓存没有开，在进行HQL的Query查询时，缓存也会失效,配置如下：
在hibernet.cfg.xml中添加

<!-- 缓存设置 -->
  <property name="hibernate.cache.use_second_level_cache">true</property>
  <property name="hibernate.cache.region.factory_class">org.hibernate.cache.ehcache.internal.EhcacheRegionFactory</property>
 <!-- 开启查询二级缓存 -->
  <property name="hibernate.cache.use_query_cache">true</property>

在查询语句中开启查询缓存
 

public void getallUser() {
		String hql="from User";
		Query query=session.createQuery(hql);
		//开启查询缓存
        query.setCacheable(true);
		
		List<User> users1=query.list();
		System.out.println(Arrays.toString(users1.toArray()));
		List<User> users2=query.list();
		System.out.println(Arrays.toString(users2.toArray()));
	}