mybatis详解-(22)整合第三方缓存Ehcache

前面几篇文章剖析了mybatis的缓存原理，发现mybatis提供的缓存是非常简陋的，用HashMap进行存储。
有专业做缓存的，那么就使用专业的缓存框架吧，这里使用Ehcache来作为mybatis的缓存。

1.引入jar

<!-- 添加Ehcache核心包 --><dependency>    <groupId>net.sf.ehcache</groupId>    <artifactId>ehcache-core</artifactId>    <version>2.6.10</version></dependency><!-- mybatis整合Ehcache的适配器 --><dependency>     <groupId>org.mybatis</groupId>     <artifactId>mybatis-ehcache</artifactId>     <version>1.0.0</version>   </dependency><!-- 引入日志包 --><dependency>    <groupId>org.slf4j</groupId>    <artifactId>slf4j-api</artifactId>    <version>1.7.12</version></dependency><dependency>    <groupId>org.slf4j</groupId>    <artifactId>slf4j-log4j12</artifactId>    <version>1.7.6</version></dependency><dependency>    <groupId>log4j</groupId>    <artifactId>log4j</artifactId>    <version>1.2.17</version></dependency>

2.引入ehcache.xml文件

添加ehcache.xml

<?xml version="1.0" encoding="UTF-8"?><ehcache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../config/ehcache.xsd">     <diskStore path="D:\mybatis\ehcache"/>        <!--        Mandatory Default Cache configuration. These settings will be applied to caches        created programmtically using CacheManager.add(String cacheName)        -->        <!--           name:缓存名称。           maxElementsInMemory：缓存最大个数。           eternal:对象是否永久有效，一但设置了，timeout将不起作用。           timeToIdleSeconds：设置对象在失效前的允许闲置时间（单位：秒）。仅当eternal=false对象不是永久有效时使用，可选属性，默认值是0，也就是可闲置时间无穷大。           timeToLiveSeconds：设置对象在失效前允许存活时间（单位：秒）。最大时间介于创建时间和失效时间之间。仅当eternal=false对象不是永久有效时使用，默认是0.，也就是对象存活时间无穷大。           overflowToDisk：当内存中对象数量达到maxElementsInMemory时，Ehcache将会对象写到磁盘中。           diskSpoolBufferSizeMB：这个参数设置DiskStore（磁盘缓存）的缓存区大小。默认是30MB。每个Cache都应该有自己的一个缓冲区。           maxElementsOnDisk：硬盘最大缓存个数。           diskPersistent：是否缓存虚拟机重启期数据 Whether the disk store persists between restarts of the Virtual Machine. The default value is false.           diskExpiryThreadIntervalSeconds：磁盘失效线程运行时间间隔，默认是120秒。           memoryStoreEvictionPolicy：当达到maxElementsInMemory限制时，Ehcache将会根据指定的策略去清理内存。默认策略是LRU（最近最少使用）。你可以设置为FIFO（先进先出）或是LFU（较少使用）。           clearOnFlush：内存数量最大时是否清除。        -->        <defaultCache                maxElementsInMemory="10"               eternal="false"           timeToIdleSeconds="120"               timeToLiveSeconds="120"               overflowToDisk="true"               maxElementsOnDisk="10000000"               diskPersistent="false"               diskExpiryThreadIntervalSeconds="120"               memoryStoreEvictionPolicy="LRU"               />     </ehcache>

3.创建示例

package org.mybatis.cache3ehcache;public class Employee {    private Integer id;    private String lastName;    private String email;    private String gender;    public Employee() {    }    public Employee(Integer id, String lastName, String email, String gender) {        this.id = id;        this.lastName = lastName;        this.email = email;        this.gender = gender;    }    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public String getLastName() {        return lastName;    }    public void setLastName(String lastName) {        this.lastName = lastName;    }    public String getEmail() {        return email;    }    public void setEmail(String email) {        this.email = email;    }    public String getGender() {        return gender;    }    public void setGender(String gender) {        this.gender = gender;    }    public String toString() {        return "Employee [id=" + id + ", lastName=" + lastName + ", email="                + email + ", gender=" + gender + "]";    }}

package org.mybatis.cache3ehcache;public interface EmployeeMapper {    public Employee getEmpById(Integer id);}

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE mapper  PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"  "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="org.mybatis.cache3ehcache.EmployeeMapper">    <!--这里引用第三方缓存（或自定义缓存）-->    <cache type="org.mybatis.caches.ehcache.EhcacheCache"></cache>    <select id="getEmpById" resultType="org.mybatis.cache3ehcache.Employee" useCache="true">        select * from mybatis_employee me where me.id = #{id}    </select></mapper>

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE configuration  PUBLIC "-//mybatis.org//DTD Config 3.0//EN"  "http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration>    <properties resource="db.properties"></properties>    <settings>        <setting name="mapUnderscoreToCamelCase" value="true"/>        <setting name="lazyLoadingEnabled" value="true" />        <setting name="aggressiveLazyLoading" value="false"/>        <!--开启缓存-->        <setting name="cacheEnabled" value="true"/>    </settings>    <typeAliases>        <!-- 为包下的所有类起别名，默认为类名大小写（不区分大小写） -->        <package name="org.mybatis.cache3ehcache"/>    </typeAliases>    <!-- 默认development是开发环境，如果改成test则表示使用测试环境 -->    <environments default="dev_mysql">        <environment id="dev_mysql">            <transactionManager type="JDBC" />            <dataSource type="POOLED">                <property name="driver" value="${mysql.driver}" />                <property name="url" value="${mysql.url}" />                <property name="username" value="${mysql.username}" />                <property name="password" value="${mysql.password}" />            </dataSource>        </environment>        <environment id="test_mysql">            <transactionManager type="JDBC"></transactionManager>            <dataSource type="POOLED">                <property name="driver" value="${mysql.drivertest}" />                <property name="url" value="${mysql.urltest}" />                <property name="username" value="${mysql.usernametest}" />                <property name="password" value="${mysql.passwordtest}" />            </dataSource>        </environment>    </environments>    <mappers>        <mapper resource="mapper/cache3ehcachemapper.xml"/>    </mappers></configuration>

测试类：

package org.mybatis.cache3ehcache;import java.io.IOException;import java.io.InputStream;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;import org.junit.Test;/** * 整个Ehcache * @author Tang */public class MybatisTest {    @Test    public void testMybatis() {        String resource = "mybatis-config-cache3ehcache.xml";//全局配置文件        InputStream inputStream = null;        SqlSessionFactory sqlSessionFactory = null;        try {            inputStream = Resources.getResourceAsStream(resource);            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);            SqlSession sqlSession1 = sqlSessionFactory.openSession();            EmployeeMapper mapper1 = sqlSession1.getMapper(EmployeeMapper.class);            Employee emp1 = mapper1.getEmpById(2);            System.out.println(emp1);            sqlSession1.close();            System.out.println("`######");            SqlSession sqlSession2 = sqlSessionFactory.openSession();            EmployeeMapper mapper2 = sqlSession2.getMapper(EmployeeMapper.class);            Employee emp2 = mapper2.getEmpById(2);            System.out.println(emp2);            sqlSession2.close();            System.out.println(emp1 == emp2);        } catch (IOException e) {            e.printStackTrace();        } finally {        }    }}

运行结果：

两个不同的sqlSession，发送了一个sql查询，说明缓存已经生效。