JPA之二级缓存

约定不等于承诺〃 2022-05-21 07:05 168阅读 0赞

`在persistence配置文件中添加缓存相关配置`

<?xml version="1.0" encoding="UTF-8"?>
    <persistence version="2.1" xmlns="http://xmlns.jcp.org/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
        <persistence-unit name="jpa" transaction-type="RESOURCE_LOCAL">
    
            
            <provider>org.hibernate.ejb.HibernatePersistence</provider>
            <class>com.heiketu.entity.User</class>
            <class>com.heiketu.entity.Order</class>
            <class>com.heiketu.entity.WindowsPhone</class>
            <class>com.heiketu.entity.Windows</class>
            <class>com.heiketu.entity.Teacher</class>
            <class>com.heiketu.entity.ClassName</class>
    
    
            
            
            <shared-cache-mode>ENABLE_SELECTIVE</shared-cache-mode>
    
            <properties>
                
                <property name="javax.persistence.jdbc.driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="javax.persistence.jdbc.url" value="jdbc:mysql:///test?serverTimezone=GMT%2B8"/>
                <property name="javax.persistence.jdbc.user" value="root"/>
                <property name="javax.persistence.jdbc.password" value="admin"/>
    
                
                <property name="hibernate.format_sql" value="true"/>
                <property name="hibernate.show_sql" value="true"/>
                <property name="hibernate.hbm2ddl.auto" value="update"/>
                
    
    
                
                
                <property name="hibernate.cache.use_second_level_cache" value="true"/>
                
                <property name="hibernate.cache.region.factory_class" value="org.hibernate.cache.ehcache.EhCacheRegionFactory"/>
                
                <property name="hibernate.cache.use_query_cache" value="true"/>
            </properties>
        </persistence-unit>
    </persistence>

在classpath下加入\*\*`ehcache.xml`\*\*ehcache缓存相关配置文件。

配置文件内容:

导入`ehcache`相关jar包:

|---ehcache-core-2.4.3.jar
    |---hibernate-ehcache-4.3.11.Final.jar
    |---slf4j-api-1.6.1.jar

在需要缓存的类上增加`@Cacheable(true)`或`@Cacheable(false)`相关标注，与`persistence`配置文件中的`<shared-cache-mode>`标签的值相呼应。

**`默认JPA开启了一级缓存`**