在mybatis一级缓存二级缓存中已经介绍过了二级缓存的大致原理。下面我们用redis来实现一下二级缓存。环境是springmvc+mybatis+redis
步骤一、引入redis相关的maven依赖
<!-- spring-redis实现 -->
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-redis</artifactId>
<version>1.6.2.RELEASE</version>
</dependency>
<!-- redis客户端jar -->
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>2.8.0</version>
</dependency>
步骤二、新建redis的配置redis.xml,redis.properties
<?xml version="1.0" encoding="utf-8"?>
<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:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="
http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd"
default-autowire="byName" default-lazy-init="false">
<!--redis数据源-->
<bean id="poolConfig" class="redis.clients.jedis.JedisPoolConfig">
<property name="maxIdle" value="${redis.maxIdle}"/>
<property name="maxTotal" value="${redis.maxActive}"/>
<property name="maxWaitMillis" value="${redis.maxWait}"/>
<property name="testOnBorrow" value="${redis.testOnBorrow}"/>
</bean>
<!--Spring-redis连接池管理工厂-->
<bean id="jedisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"
p:hostName="${redis.host}" p:port="${redis.port}"
p:password="${redis.pass}" p:poolConfig-ref="poolConfig"/>
<!-- 使用中间类解决RedisCache.jedisConnectionFactory的静态注入，从而使MyBatis实现第三方缓存 -->
<bean id="redisCacheTransfer" class="com.yihaomen.mybatis.cache.RedisCacheTransfer">
<property name="jedisConnectionFactory" ref="jedisConnectionFactory"/>
</bean>
</beans>
redis.host=192.168.31.55
redis.port=6379
redis.pass=
redis.maxIdle=300
redis.maxActive=600
redis.maxWait=1000
redis.testOnBorrow=true
步骤三、将redis.xml引入到spring的配置文件applicationContext.xml
<bean id="propertyConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath*:jdbc.properties</value>
<value>classpath*:redis.properties</value>
</list>
</property>
</bean>
<import resource="redis.xml"/>
步骤四、创建缓存实现类RedisCache
package com.yihaomen.mybatis.cache; import org.apache.ibatis.cache.Cache;
import org.springframework.data.redis.connection.jedis.JedisConnection;
import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;
import org.springframework.data.redis.serializer.JdkSerializationRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializer;
import redis.clients.jedis.exceptions.JedisConnectionException; import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock; /**
*
* @ProjectName: springmvc-mybatis
* @Description: 使用第三方内存数据库Redis作为二级缓存
* @author: lisen
* @date: 2017/11/8
*/
public class RedisCache implements Cache{ private static JedisConnectionFactory jedisConnectionFactory; private final String id; private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock(); public RedisCache(final String id) {
if(id == null) {
throw new IllegalArgumentException("Cache instances require an ID");
}
this.id = id;
} public static void setJedisConnectionFactory(JedisConnectionFactory jedisConnectionFactory) {
RedisCache.jedisConnectionFactory = jedisConnectionFactory;
} @Override
public String getId() {
return this.id;
} public void putObject(Object key, Object value) {
JedisConnection connection = null;
try {
connection = jedisConnectionFactory.getConnection();
RedisSerializer<Object> serializer = new JdkSerializationRedisSerializer();
connection.set(serializer.serialize(key), serializer.serialize(value));
} catch (JedisConnectionException e) {
e.printStackTrace();
} finally {
if(connection != null) {
connection.close();
}
}
} public Object getObject(Object key) {
Object result = null;
JedisConnection connection = null;
try {
connection = jedisConnectionFactory.getConnection();
RedisSerializer<Object> serializer = new JdkSerializationRedisSerializer();
result = serializer.deserialize(connection.get(serializer.serialize(key)));
} catch (JedisConnectionException e) {
e.printStackTrace();
} finally {
if(connection != null) {
connection.close();
}
}
return result;
} public Object removeObject(Object key) {
JedisConnection connection = null;
Object result = null;
try {
connection = jedisConnectionFactory.getConnection();
RedisSerializer<Object> serializer = new JdkSerializationRedisSerializer();
result = connection.expire(serializer.serialize(key), 0);
} catch (JedisConnectionException e) {
e.printStackTrace();
} finally {
if(connection != null) {
connection.close();
}
}
return result;
} @Override
public void clear() {
JedisConnection connection = null;
try {
connection = jedisConnectionFactory.getConnection();
connection.flushDb();
connection.flushAll();
} catch (JedisConnectionException e) {
e.printStackTrace();
} finally {
if(connection != null) {
connection.close();
}
}
} public int getSize() {
int result = 0;
JedisConnection connection = null;
try {
connection = jedisConnectionFactory.getConnection();
result = Integer.valueOf(connection.dbSize().toString());
} catch (JedisConnectionException e) {
e.printStackTrace();
} finally {
if(connection != null) {
connection.close();
}
}
return result;
} public ReadWriteLock getReadWriteLock() {
return this.readWriteLock;
}
}
步骤五、 创建中间类RedisCacheTransfer，完成RedisCache.jedisConnectionFactory的静态注入
package com.yihaomen.mybatis.cache; import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.connection.jedis.JedisConnectionFactory; /**
*
* @ProjectName: springmvc-mybatis
* @Description: 创建中间类RedisCacheTransfer，完成RedisCache.jedisConnectionFactory的静态注入,
* 静态注入中间类
* @author: lisen
* @date: 2017/11/8
*/
public class RedisCacheTransfer { @Autowired
public void setJedisConnectionFactory(JedisConnectionFactory jedisConnectionFactory) {
RedisCache.setJedisConnectionFactory(jedisConnectionFactory);
}
}
步骤六、在mapper(User.xml)中加入MyBatis二级缓存
<?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="com.yihaomen.mybatis.dao.UserMapper">
<cache type="com.yihaomen.mybatis.cache.RedisCache"/>
<select id="selectUserByID" parameterType="int" resultType="User" >
select * from `user` where id = #{id}
</select>
</mapper>
我们还可以配置在SQL层面上的缓存配置，来决定它们是否需要使用或者刷新缓存，我们往往根据两个属性：userCache和flushCache来完成，其中userCache表示是否需要使用缓存，儿flushCache表示插入后是否需要刷新缓存，比如
<select ... flushCache="false" useCache="true"/>
<insert ... flushCache="true"/>
<update... flushCache="true"/>
<delete... flushCache="true"/>
步骤七、在mybatis-config.xml文件中开启二级缓存
<settings>
<!--这个配置使全局的映射器(二级缓存)启用或禁用缓存-->
<setting name="cacheEnabled" value="true" />
</setting>
步骤八、单元测试
package com.yihaomen.service.test; import com.yihaomen.mybatis.dao.UserMapper;
import com.yihaomen.mybatis.model.User;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner; import java.util.List; /**
*
* @ProjectName: springmvc-mybatis
* @Description:
* @author: lisen
* @date: 2017/11/9
*/
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration({"classpath:applicationContext.xml"})
public class UserSpringTest {
@Autowired
private UserMapper userMapper; @Test
public void selectUserById() {
List<User> users = userMapper.selectUserById(11L);
} }
https://gitee.com/huayicompany/springmvc-mybatis
参考：
[1]博客，http://blog.csdn.net/xiadi934/article/details/50786293