hibernate缓存ehcache用法

一级缓存：session级别

二级缓存：sessionFactory级别

查询缓存：相同的SQL语句，不再重复执行

默认情况下，hibernate已经支持一级缓存了。

要支持二级缓存，步骤如下：

在spring配置文件applicationContext.xml中加入下面配置：

	<!-- cache manager -->
	<bean id="cacheManager"
		class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">
		<property name="shared" value="true" />
		<property name="configLocation" value="classpath:ehcache.xml" />
	</bean>
	<bean id="ehCache" class="org.springframework.cache.ehcache.EhCacheFactoryBean">
		<property name="cacheManager" ref="cacheManager" />
		<property name="cacheName" value="root" />
	</bean>

同时需要在hibernate的配置文件hibernate.cfg.xml中添加下面配置(下面包括了查询缓存和二级缓存)：

		<!-- use query cache -->
		<property name="hibernate.cache.use_query_cache">true</property>
                <!-- user second level cache -->
		<property name="hibernate.cache.use_second_level_cache">true</property>
		<property name="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</property>

以及ehcache.xml(ehcache自身的配置文件):

<?xml version="1.0" encoding="UTF-8" ?>
<ehcache>

	<diskStore path="java.io.tmpdir"/>
	
	<defaultCache 
        eternal="false"
        timeToIdleSeconds="1200"
        timeToLiveSeconds="3600"
		maxElementsInMemory="10000" 
		overflowToDisk="true">
	</defaultCache>
	
	<cache   
        name="org.hibernate.cache.StandardQueryCache"    
        maxElementsInMemory="50"
        eternal="false"
        timeToIdleSeconds="3600"
        timeToLiveSeconds="7200"
        overflowToDisk="false"
    />   
  
    <cache   
        name="org.hibernate.cache.UpdateTimestampsCache"
        maxElementsInMemory="5000"
        eternal="false"
        timeToIdleSeconds="3600"
        timeToLiveSeconds="7200"
        overflowToDisk="false"
    />
</ehcache>

另外，假如我们需要对User这个类进行缓存，需要加下面注解：@cache ，如果映射方式是通过xml的方式的话，需要用另外的方式，这里就不多说了

package com.tch.test.ssh.entity.annotation;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

import org.hibernate.annotations.Cache;
import org.hibernate.annotations.CacheConcurrencyStrategy;


/**
 * User entity. @author MyEclipse Persistence Tools
 */
@Entity
@Table(name="user")
@Cache(usage=CacheConcurrencyStrategy.READ_WRITE)
public class User implements java.io.Serializable {

	// Fields


	private static final long serialVersionUID = 1L;
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	private Integer id;
	private String name;
	private String password;
	//private Set<Priority> priorities;

	// Constructors

	@Override
	public String toString() {
		return "User [id=" + id + ", name=" + name + ", password=" + password
				 + "]";
	}

	/** default constructor */
	public User() {
	}

	/** full constructor */
	public User(String name, String password) {
		this.name = name;
		this.password = password;
	}

	// Property accessors

	public Integer getId() {
		return this.id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getName() {
		return this.name;
	}

	public void setName(String name) {
		this.name = name;
	}


	public String getPassword() {
		return this.password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

}

然后就可以使用了：

假如我们页面有个地方，多次调用了Dao层的一个load方法：

	public void load() {
		User u = (User) getSession().load(User.class, 2);
		System.out.println(u);
	}

那么就会发现，多次调用该方法，但是执行的SQL语句，只执行了一次，没有多次执行，这就表明二级缓存起作用啦。

注意，session 的 load方法会使用缓存，但是query 的 list 方法只会往缓存中放数据，不会从缓存取数据，所以使用list是不行的，会发出多次SQL语句

要解决list的缓存问题，就用到了下面的查询缓存了。

查询缓存：解决相同SQL语句的多次执行问题，注意，SQL语句不同的话，是不能使用二级缓存和查询缓存的。

同时，查询缓存依赖于二级缓存，所以需要配置二级缓存：

		<!-- use query cache -->
		<property name="hibernate.cache.use_query_cache">true</property>
		<!-- use second level cache -->
		<property name="hibernate.cache.use_second_level_cache">true</property>
		<property name="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</property>

其它的同二级缓存，但是需要额外添加的操作就是，在query的list操作之前，需要调用setCacheable(true) ：

session.createQuery(hql).setCacheable(true).list();

这样就可以实现相同SQL语句的查询缓存了。

下面贴上部分代码：

applicationContext.xml ：

<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
				http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd
				http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">
	<!-- 启动注入功能 -->
	<context:annotation-config />
	<!-- 启动扫描component功能 -->
	<context:component-scan base-package="com.tch.test.ssh" />
	<!-- 启动注解实物配置功能 -->
	<tx:annotation-driven transaction-manager="transactionManager" />
	<!-- 事务管理器 -->
	<bean id="transactionManager"
		class="org.springframework.orm.hibernate3.HibernateTransactionManager">
		<property name="sessionFactory" ref="sessionFactory" />
	</bean>

	<!--读取数据库配置文件  -->
	<bean id="sessionFactory"
		class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
		<property name="mappingLocations">
			<list>
				<!-- <value>classpath*:com/tch/test/ssh/entity/*.hbm.xml</value> -->
			</list>
		</property>
		<property name="packagesToScan">
			<list>
				<value>com.tch.test.ssh.entity.annotation</value>
			</list>
		</property>
		<property name="configLocation">
			<value>classpath:hibernate.cfg.xml</value>
		</property>
	</bean>

	<!-- cache manager -->
	<bean id="cacheManager"
		class="org.springframework.cache.ehcache.EhCacheManagerFactoryBean">
		<property name="shared" value="true" />
		<property name="configLocation" value="classpath:ehcache.xml" />
	</bean>
	<bean id="ehCache" class="org.springframework.cache.ehcache.EhCacheFactoryBean">
		<property name="cacheManager" ref="cacheManager" />
		<property name="cacheName" value="root" />
	</bean>
</beans>

ehcache.xml ：

<?xml version="1.0" encoding="UTF-8" ?>
<ehcache>

	<diskStore path="java.io.tmpdir"/>
	
	<defaultCache 
        eternal="false"
        timeToIdleSeconds="3600"
        timeToLiveSeconds="7200"
		maxElementsInMemory="10000" 
		overflowToDisk="true">
	</defaultCache>
	
	<cache   
        name="org.hibernate.cache.StandardQueryCache"    
        maxElementsInMemory="50"
        eternal="false"
        timeToIdleSeconds="3600"
        timeToLiveSeconds="7200"
        overflowToDisk="false"
    />   
  
    <cache   
        name="org.hibernate.cache.UpdateTimestampsCache"
        maxElementsInMemory="5000"
        eternal="false"
        timeToIdleSeconds="3600"
        timeToLiveSeconds="7200"
        overflowToDisk="false"
    />
</ehcache>

hibernate.cfg.xml ：

<?xml version='1.0' encoding='utf-8'?>
<!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="hibernate.connection.provider_class">org.hibernate.connection.ProxoolConnectionProvider</property>
		<property name="hibernate.proxool.xml">proxool.xml</property>
		<property name="hibernate.proxool.pool_alias">local_proxool</property>
		<property name="dialect">org.hibernate.dialect.MySQL5Dialect</property>
		<property name="current_session_context_class">thread</property>
		<!-- use query cache -->
		<property name="hibernate.cache.use_query_cache">true</property>
		<!-- use second level cache -->
		<property name="hibernate.cache.use_second_level_cache">true</property>
		<property name="hibernate.cache.provider_class">org.hibernate.cache.EhCacheProvider</property>
		<property name="show_sql">true</property>
		<property name="hbm2ddl.auto">update</property>
	</session-factory>
</hibernate-configuration>

proxool.xml (数据库连接池的配置，和本文无关):

<?xml version="1.0" encoding="UTF-8"?>
<something-else-entirely>
  <proxool>
  
    <alias>local_proxool</alias>
    <driver-url>jdbc:mysql://localhost:3306/test?useUnicode=true&amp;characterEncoding=UTF-8&amp;zeroDateTimeBehavior=convertToNull</driver-url>
    <driver-class>com.mysql.jdbc.Driver</driver-class>
    <driver-properties>
      <property name="user" value="root"/>
      <property name="password" value="root"/>
    </driver-properties>
    
    <house-keeping-sleep-time>90000</house-keeping-sleep-time>
   
    <house-keeping-test-sql>select CURRENT_DATE</house-keeping-test-sql>
     
    <prototype-count>4</prototype-count>
   
    <simultaneous-build-throttle>50</simultaneous-build-throttle>
   
    <maximum-connection-count>300</maximum-connection-count>
   
    <minimum-connection-count>2</minimum-connection-count>
   
    <maximum-connection-lifetime>3600000</maximum-connection-lifetime>
  </proxool>
</something-else-entirely>

struts.xml ：（个人测试使用的SSH的项目）

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE struts PUBLIC
	"-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
	"http://struts.apache.org/dtds/struts-2.3.dtd">
<struts>
	<constant name="struts.enable.DynamicMethodInvocation" value="true" />
	<constant name="struts.devMode" value="true" />
	<package name="default" namespace="/" extends="struts-default">
		
		<action name="show" class="userAction" method="show">
			<result>/WEB-INF/pages/User.jsp</result>
		</action>
		<action name="load" class="userAction" method="load">
			<result>/WEB-INF/pages/User.jsp</result>
		</action>
		
	</package>
</struts>

其中后台的load对应的action最终调用的DAO层的load方法：

	@Override
	public void load() {
		User u = (User) getSession().load(User.class, 2);
		System.out.println(u);
	}

多次调用该方法，会发现，只执行了一次SQL，这就是缓存的作用啦

后台的show对应的action最终调用的DAO层的show方法：

@Override
	public List  show() {
		return getSession().createQuery("from User").setCacheable(true).list();
	}

其中User类：

package com.tch.test.ssh.entity.annotation;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

import org.hibernate.annotations.Cache;
import org.hibernate.annotations.CacheConcurrencyStrategy;


/**
 * User entity. @author MyEclipse Persistence Tools
 */
@Entity
@Table(name="user")
@Cache(usage=CacheConcurrencyStrategy.READ_WRITE)
public class User implements java.io.Serializable {

	// Fields


	private static final long serialVersionUID = 1L;
	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	private Integer id;
	private String name;
	private String password;
	//private Set<Priority> priorities;

	// Constructors

	@Override
	public String toString() {
		return "User [id=" + id + ", name=" + name + ", password=" + password
				 + "]";
	}

	/** default constructor */
	public User() {
	}

	/** full constructor */
	public User(String name, String password) {
		this.name = name;
		this.password = password;
	}

	// Property accessors

	public Integer getId() {
		return this.id;
	}

	public void setId(Integer id) {
		this.id = id;
	}

	public String getName() {
		return this.name;
	}

	public void setName(String name) {
		this.name = name;
	}


	public String getPassword() {
		return this.password;
	}

	public void setPassword(String password) {
		this.password = password;
	}

}

好了，不早了，睡觉。。。

hibernate缓存ehcache用法

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