二级缓存是多个SqlSession共享的,其作用域是mapper的同一个namespace,不同的sqlSession两次执行相同namespace下的sql语句且向sql中传递参数也相同即最终执行相同的sql语句,第一次执行完毕会将数据库中查询的数据写到缓存(内存),第二次会从缓存中获取数据将不再从数据库查询,从而提高查询效率。Mybatis默认没有开启二级缓存需要在setting全局参数中配置开启二级缓存。
下面是使用Redis来作为Mybatis二级缓存的实例:
Redis的安装使用的是Docker,Docker的简介
在application.properties文件中配置Redis,Mybatis,开启Mybatis二级缓存等:
server.port=80
# 数据源配置
spring.datasource.url=jdbc:mysql://localhost:3306/ssb_test
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=root
#连接池配置
#spring.datasource.type=org.apache.commons.dbcp2.BasicDataSource
#mybatis
#entity扫描的包名
mybatis.type-aliases-package=com.xiaolyuh.domain.model
#Mapper.xml所在的位置
mybatis.mapper-locations=classpath*:/mybaits/*Mapper.xml
#开启MyBatis的二级缓存
mybatis.configuration.cache-enabled=true
#pagehelper
pagehelper.helperDialect=mysql
pagehelper.reasonable=true
pagehelper.supportMethodsArguments=true
pagehelper.params=count=countSql
#日志配置
logging.level.com.xiaolyuh=debug
logging.level.org.springframework.web=debug
logging.level.org.springframework.transaction=debug
logging.level.org.mybatis=debug
#redis
#database name
spring.redis.database=0
#server host
spring.redis.host=192.168.195.128
#server password
spring.redis.password=
#connection port
spring.redis.port=6378
#spring.redis.pool.max-idle=8 # pool settings ...
#spring.redis.pool.min-idle=0
#spring.redis.pool.max-active=8
#spring.redis.pool.max-wait=-1
#spring.redis.sentinel.master= # name of Redis server
#spring.redis.sentinel.nodes= # comma-separated list of host:port pairs
debug=false
xmlns ="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
4.0.0
spring-boot-student-mybatis-redis
jar
spring-boot-student-mybatis-redis
Demo Mybatis Redis for Spring Boot
com.xiaolyuh
spring-boot-student
0.0.1-SNAPSHOT
UTF-8
UTF-8
1.8
org.springframework.boot
spring-boot-starter-web
org.springframework.boot
spring-boot-starter-data-redis
mysql
mysql-connector-java
org.mybatis.spring.boot
mybatis-spring-boot-starter
1.3.0
com.github.pagehelper
pagehelper-spring-boot-starter
1.1.1
com.alibaba
fastjson
1.2.31
org.mybatis
mybatis-ehcache
1.0.0
package com.xiaolyuh.config;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
@Configuration
public class RedisConfig {
/**
* 重写Redis序列化方式,使用Json方式:
* 当我们的数据存储到Redis的时候,我们的键(key)和值(value)都是通过Spring提供的Serializer序列化到数据库的。RedisTemplate默认使用的是JdkSerializationRedisSerializer,StringRedisTemplate默认使用的是StringRedisSerializer。
* Spring Data JPA为我们提供了下面的Serializer:
* GenericToStringSerializer、Jackson2JsonRedisSerializer、JacksonJsonRedisSerializer、JdkSerializationRedisSerializer、OxmSerializer、StringRedisSerializer。
* 在此我们将自己配置RedisTemplate并定义Serializer。
* @param redisConnectionFactory
* @return
*/
@Bean
public RedisTemplate redisTemplate(RedisConnectionFactory redisConnectionFactory) {
RedisTemplate redisTemplate = new RedisTemplate<>();
redisTemplate.setConnectionFactory(redisConnectionFactory);
Jackson2JsonRedisSerializer
通过Spring Aware(容器感知)来获取到ApplicationContext,然后根据ApplicationContext获取容器中的Bean。
package com.xiaolyuh.holder;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;
/**
* 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候中取出ApplicaitonContext.
*/
@Component
public class SpringContextHolder implements ApplicationContextAware {
private static ApplicationContext applicationContext;
/**
* 实现ApplicationContextAware接口的context注入函数, 将其存入静态变量.
*/
public void setApplicationContext(ApplicationContext applicationContext) {
SpringContextHolder.applicationContext = applicationContext; // NOSONAR
}
/**
* 取得存储在静态变量中的ApplicationContext.
*/
public static ApplicationContext getApplicationContext() {
checkApplicationContext();
return applicationContext;
}
/**
* 从静态变量ApplicationContext中取得Bean, 自动转型为所赋值对象的类型.
*/
@SuppressWarnings("unchecked")
public static T getBean(String name) {
checkApplicationContext();
return (T) applicationContext.getBean(name);
}
/**
* 从静态变量ApplicationContext中取得Bean, 自动转型为所赋值对象的类型.
*/
@SuppressWarnings("unchecked")
public static T getBean(Class clazz) {
checkApplicationContext();
return (T) applicationContext.getBeansOfType(clazz);
}
/**
* 清除applicationContext静态变量.
*/
public static void cleanApplicationContext() {
applicationContext = null;
}
private static void checkApplicationContext() {
if (applicationContext == null) {
throw new IllegalStateException("applicaitonContext未注入,请在applicationContext.xml中定义SpringContextHolder");
}
}
}
自定义缓存需要实现Mybatis的Cache接口,我这里将使用Redis来作为缓存的容器。
package com.xiaolyuh.cache;
import com.xiaolyuh.holder.SpringContextHolder;
import org.apache.ibatis.cache.Cache;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.dao.DataAccessException;
import org.springframework.data.redis.connection.RedisConnection;
import org.springframework.data.redis.core.RedisCallback;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.util.CollectionUtils;
import java.util.Collections;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
/**
* 使用Redis来做Mybatis的二级缓存
* 实现Mybatis的Cache接口
*/
public class MybatisRedisCache implements Cache {
private static final Logger logger = LoggerFactory.getLogger(MybatisRedisCache.class);
// 读写锁
private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock(true);
private RedisTemplate redisTemplate = SpringContextHolder.getBean("redisTemplate");
private String id;
public MybatisRedisCache(final String id) {
if (id == null) {
throw new IllegalArgumentException("Cache instances require an ID");
}
logger.info("Redis Cache id " + id);
this.id = id;
}
@Override
public String getId() {
return this.id;
}
@Override
public void putObject(Object key, Object value) {
if (value != null) {
// 向Redis中添加数据,有效时间是2天
redisTemplate.opsForValue().set(key.toString(), value, 2, TimeUnit.DAYS);
}
}
@Override
public Object getObject(Object key) {
try {
if (key != null) {
Object obj = redisTemplate.opsForValue().get(key.toString());
return obj;
}
} catch (Exception e) {
logger.error("redis ");
}
return null;
}
@Override
public Object removeObject(Object key) {
try {
if (key != null) {
redisTemplate.delete(key.toString());
}
} catch (Exception e) {
}
return null;
}
@Override
public void clear() {
logger.debug("清空缓存");
try {
Set keys = redisTemplate.keys("*:" + this.id + "*");
if (!CollectionUtils.isEmpty(keys)) {
redisTemplate.delete(keys);
}
} catch (Exception e) {
}
}
@Override
public int getSize() {
Long size = (Long) redisTemplate.execute(new RedisCallback() {
@Override
public Long doInRedis(RedisConnection connection) throws DataAccessException {
return connection.dbSize();
}
});
return size.intValue();
}
@Override
public ReadWriteLock getReadWriteLock() {
return this.readWriteLock;
}
}
namespace ="com.xiaolyuh.domain.mapper.PersonMapper">
type ="com.xiaolyuh.cache.MybatisRedisCache">
name ="eviction" value="LRU" />
name ="flushInterval" value="6000000" />
name ="size" value="1024" />
name ="readOnly" value="false" />
id ="BaseResultMap" type="com.xiaolyuh.domain.model.Person">
column ="id" property="id" jdbcType="BIGINT"/>
column ="name" property="name" jdbcType="VARCHAR"/>
column ="age" property="age" jdbcType="INTEGER"/>
column ="address" property="address" jdbcType="VARCHAR"/>
id ="Base_Column_List">
id, name, age, address
="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Long">
select
refid ="Base_Column_List"/>
from person
where id = #{id,jdbcType=BIGINT}
id ="deleteByPrimaryKey" parameterType="java.lang.Long">
delete from person
where id = #{id,jdbcType=BIGINT}
id ="insert" parameterType="com.xiaolyuh.domain.model.Person">
resultType ="java.lang.Long" keyProperty="id" order="AFTER">
SELECT LAST_INSERT_ID()
insert into person (name, age, address
)
values (#{name,jdbcType=VARCHAR}, #{age,jdbcType=INTEGER}, #{address,jdbcType=VARCHAR}
)
id ="insertSelective" parameterType="com.xiaolyuh.domain.model.Person">
resultType ="java.lang.Long" keyProperty="id" order="AFTER">
SELECT LAST_INSERT_ID()
insert into person
prefix ="(" suffix=")" suffixOverrides=",">
test ="name != null">
name,
test ="age != null">
age,
test ="address != null">
address,
prefix ="values (" suffix=")" suffixOverrides=",">
test ="name != null">
#{name,jdbcType=VARCHAR},
test ="age != null">
#{age,jdbcType=INTEGER},
test ="address != null">
#{address,jdbcType=VARCHAR},
id ="updateByPrimaryKeySelective" parameterType="com.xiaolyuh.domain.model.Person">
update person
test ="name != null">
name = #{name,jdbcType=VARCHAR},
test ="age != null">
age = #{age,jdbcType=INTEGER},
test ="address != null">
address = #{address,jdbcType=VARCHAR},
where id = #{id,jdbcType=BIGINT}
id ="updateByPrimaryKey" parameterType="com.xiaolyuh.domain.model.Person">
update person
set name = #{name,jdbcType=VARCHAR},
age = #{age,jdbcType=INTEGER},
address = #{address,jdbcType=VARCHAR}
where id = #{id,jdbcType=BIGINT}
="findAll" resultMap="BaseResultMap" useCache="true">
select
refid ="Base_Column_List"/>
from person
="findByPage" resultMap="BaseResultMap" useCache="false">
select
refid ="Base_Column_List"/>
from person
package com.xiaolyuh.domain.mapper;
import com.github.pagehelper.Page;
import com.xiaolyuh.domain.model.Person;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;
@Mapper//声明成mybatis Dao层的Bean,也可以在配置类上使用@MapperScan("com.xiaolyuh.domain.mapper")注解声明
public interface PersonMapper {
int deleteByPrimaryKey(Long id);
int insert(Person record);
int insertSelective(Person record);
Person selectByPrimaryKey(Long id);
int updateByPrimaryKeySelective(Person record);
int updateByPrimaryKey(Person record);
/**
* 获取所有数据
* @return
*/
List findAll();
/**
* 分页查询数据
* @return
*/
Page findByPage();
}
package com.xiaolyuh.domain.model;
import java.io.Serializable;
public class Person implements Serializable {
private static final long serialVersionUID = 1L;
private Long id;
/**
* 名称
*/
private String name;
/**
* 年龄
*/
private Integer age;
/**
* 地址
*/
private String address;
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public Integer getAge() {
return age;
}
public void setAge(Integer age) {
this.age = age;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
@Override
public String toString() {
return "Person{" +
"id=" + id +
", name='" + name + '\'' +
", age=" + age +
", address='" + address + '\'' +
'}';
}
}
package com.xiaolyuh.service;
import com.github.pagehelper.Page;
import com.xiaolyuh.domain.model.Person;
import java.util.List;
/**
* Created by yuhao.wang on 2017/6/19.
*/
public interface PersonService {
List findAll();
/**
* 分页查询
* @param pageNo 页号
* @param pageSize 每页显示记录数
* @return
*/
Page findByPage(int pageNo, int pageSize);
void insert(Person person);
}
package com.xiaolyuh.service.impl;
import com.github.pagehelper.Page;
import com.github.pagehelper.PageHelper;
import com.xiaolyuh.domain.mapper.PersonMapper;
import com.xiaolyuh.domain.model.Person;
import com.xiaolyuh.service.PersonService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import java.util.List;
/**
* Created by yuhao.wang on 2017/6/19.
*/
@Service
@Transactional(readOnly = true)
public class PersonServiceImpl implements PersonService {
@Autowired
private PersonMapper personMapper;
@Override
public List findAll() {
return personMapper.findAll();
}
@Override
public Page findByPage(int pageNo, int pageSize) {
PageHelper.startPage(pageNo, pageSize);
return personMapper.findByPage();
}
@Override
@Transactional
public void insert(Person person) {
personMapper.insert(person);
}
}
package com.xiaolyuh;
import com.alibaba.fastjson.JSON;
import com.github.pagehelper.Page;
import com.xiaolyuh.domain.model.Person;
import com.xiaolyuh.holder.SpringContextHolder;
import com.xiaolyuh.service.PersonService;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.test.context.junit4.SpringRunner;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.TimeUnit;
@RunWith(SpringRunner.class)
@SpringBootTest
public class PersonMapperTests {
private Logger logger = LoggerFactory.getLogger(PersonMapperTests.class);
@Autowired
private PersonService personService;
@Autowired
private RedisTemplate redisTemplate;
Person person = null;
@Before
public void testInsert() {
person = new Person();
person.setName("测试");
person.setAddress("address");
person.setAge(10);
personService.insert(person);
Assert.assertNotNull(person.getId());
logger.debug(JSON.toJSONString(person));
}
@Test
public void testFindAll() {
List persons = personService.findAll();
Assert.assertNotNull(persons);
logger.debug(JSON.toJSONString(persons));
}
@Test
public void testFindByPage() {
Page persons = personService.findByPage(1, 2);
Assert.assertNotNull(persons);
logger.debug(persons.toString());
logger.debug(JSON.toJSONString(persons));
}
// 测试mybatis缓存
@Test
public void testCache() {
long begin = System.currentTimeMillis();
List persons = personService.findAll();
long ing = System.currentTimeMillis();
personService.findAll();
long end = System.currentTimeMillis();
logger.debug("第一次请求时间:" + (ing - begin) + "ms");
logger.debug("第二次请求时间:" + (end - ing) + "ms");
Assert.assertNotNull(persons);
logger.debug(JSON.toJSONString(persons));
}
// 测试Redis存储和获取一个List
@Test
public void testRedisCacheSetList() {
List persons = new ArrayList<>();
persons.add(person);
persons.add(person);
persons.add(person);
redisTemplate.opsForValue().set(person.getId() + "", persons, 2, TimeUnit.MINUTES);
persons = (List) redisTemplate.opsForValue().get(person.getId() + "");
System.out.println(JSON.toJSONString(persons));
}
// 测试Redis存储和获取一个Object
@Test
public void testRedisCacheSetObject() {
redisTemplate.opsForValue().set(person.getId() + "", person, 2, TimeUnit.MINUTES);
Object p = redisTemplate.opsForValue().get(person.getId() + "");
if (p instanceof Person) {
Person person1 = (Person) p;
System.out.println(JSON.toJSONString(person1));
}
}
// 测试 通过Spring Aware获取Spring容器中的额Bean
@Test
public void testApplicationContextAware() {
RedisTemplate redisTemplate = SpringContextHolder.getBean("redisTemplate");
System.out.println(redisTemplate);
}
}
2017-06-29 15:22:22.351 DEBUG 12976 --- [ main] com.xiaolyuh.domain.mapper.PersonMapper : Cache Hit Ratio [com.xiaolyuh.domain.mapper.PersonMapper]: 0.5
2017-06-29 15:22:22.351 DEBUG 12976 --- [ main] org.mybatis.spring.SqlSessionUtils : Releasing transactional SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2b2a4332]
2017-06-29 15:22:22.351 DEBUG 12976 --- [ main] org.mybatis.spring.SqlSessionUtils : Transaction synchronization committing SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2b2a4332]
2017-06-29 15:22:22.351 DEBUG 12976 --- [ main] org.mybatis.spring.SqlSessionUtils : Transaction synchronization deregistering SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2b2a4332]
2017-06-29 15:22:22.351 DEBUG 12976 --- [ main] org.mybatis.spring.SqlSessionUtils : Transaction synchronization closing SqlSession [org.apache.ibatis.session.defaults.DefaultSqlSession@2b2a4332]
2017-06-29 15:22:22.353 DEBUG 12976 --- [ main] com.xiaolyuh.PersonMapperTests : 第一次请求时间:92ms
2017-06-29 15:22:22.354 DEBUG 12976 --- [ main] com.xiaolyuh.PersonMapperTests : 第二次请求时间:68ms
https://github.com/wyh-spring-ecosystem-student/spring-boot-student/tree/releases
spring-boot-student-mybatis-redis工程