智慧政务门户网站建设研究,东家乐装修公司简介,网络营销模式有哪几种,东莞黄页网广告【Mybatis-Plus】Mybatis-Plus 二级缓存全详解
一#xff0c;Mybatis-Plus介绍
MyBatis-Plus#xff08;简称MP#xff09;是一个基于 MyBatis 的增强工具#xff0c;它简化了 MyBatis 的开发#xff0c;并且提供了许多便利的功能#xff0c;帮助开发者更高效地进行持久…【Mybatis-Plus】Mybatis-Plus 二级缓存全详解
一Mybatis-Plus介绍
MyBatis-Plus简称MP是一个基于 MyBatis 的增强工具它简化了 MyBatis 的开发并且提供了许多便利的功能帮助开发者更高效地进行持久层的开发。
二Mybatis-Plus缓存级别 一级缓存二级缓存
MyBatis-Plus 与 MyBatis 一样也依赖于 MyBatis 的缓存机制包括一级缓存本地缓存和二级缓存全局缓存。 一级缓存本地缓存 一级缓存是指在同一个 SqlSession 内部的缓存。它默认是开启的且无法关闭。当执行查询语句时如果之前已经从数据库中查询过相同的结果则会直接从缓存中获取结果而不需要再次查询数据库。一级缓存的作用范围是 SqlSession 级别的也就是说只有在同一个 SqlSession 中执行的查询操作才会共享同一个一级缓存。当 SqlSession 关闭时一级缓存将被清空这意味着一级缓存的生命周期与 SqlSession 是一致的。 二级缓存全局缓存 二级缓存是指多个 SqlSession 之间共享的缓存它的作用范围是 Mapper 级别的。二级缓存需要手动开启和配置可以通过在 Mapper 接口或者 XML 配置文件中添加 cache 标签来配置。当执行查询语句时如果之前已经从数据库中查询过相同的结果并且该结果被保存在二级缓存中则会直接从缓存中获取结果而不需要再次查询数据库。二级缓存的生命周期是全局的在多个 SqlSession 中共享但是它需要考虑缓存的一致性和并发访问的安全性。在更新数据时需要手动清除或刷新二级缓存以保证数据的正确性。
总的来说一级缓存是 SqlSession 级别的缓存而二级缓存是 Mapper 级别的缓存。一级缓存默认开启且无法关闭而二级缓存需要手动配置开启。
Spring Boot 整合Mybatis 开启二级缓存
图片来源与CSDN 半缘修道_半缘君
1.POM依赖
dependencygroupIdorg.springframework.boot/groupIdartifactIdspring-boot-starter-data-redis/artifactId
/dependency
dependencygroupIdcom.baomidou/groupIdartifactIdmybatis-plus-boot-starter/artifactIdversion3.3.2/version
/dependency
dependencygroupIdmysql/groupIdartifactIdmysql-connector-java/artifactIdscoperuntime/scope
/dependencydependencygroupIdorg.apache.commons/groupIdartifactIdcommons-pool2/artifactId
/dependency2.类代码
1. 编写Redis工具类RedisUtils
import org.springframework.data.redis.core.RedisCallback;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.util.CollectionUtils;import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.TimeUnit;/**** Redis工具类,一般企业开发常用的一个工具类不会去用原生的redis配置类**/public final class RedisUtils {private RedisTemplateString, Object redisTemplate;public RedisUtils(RedisTemplateString, Object redisTemplate) {this.redisTemplate redisTemplate;}public Object execute(RedisCallback action){Object execute redisTemplate.execute(action);return execute;}/*** 删除CollectionString集合中的key* param keys* return*/public Long del(CollectionString keys){Long delete redisTemplate.delete(keys);return delete;}/*** 模糊查询key* param str 模糊查询的条件* return*/public SetString keys(String str){SetString keys redisTemplate.keys(str);return keys;}/*** 消息订阅与发布发布* param channel* param message*/public void convertAndSend(String channel, Object message){redisTemplate.convertAndSend(channel,message);}/*** 如果不存在且保存的时间大于0即可创建成功否则创建失败* param key 键* param value 值* param time 缓存的时间* return*/public boolean setNx(String key,Object value,long time){try {if (time 0) {return redisTemplate.opsForValue().setIfAbsent(key,value,time,TimeUnit.SECONDS);} else {return false;}} catch (Exception e) {e.printStackTrace();return false;}}/*** 如果不存在才创建成功否则就创建失败* param key* param value* return*/public boolean setNx(String key,Object value){try {return redisTemplate.opsForValue().setIfAbsent(key, value);} catch (Exception e) {e.printStackTrace();return false;}}// commonpublic boolean expire(String key, long time) {try {if (time 0) {redisTemplate.expire(key, time, TimeUnit.SECONDS);}return true;} catch (Exception e) {e.printStackTrace();return false;}}public long getExpire(String key) {return redisTemplate.getExpire(key, TimeUnit.SECONDS);}public boolean hasKey(String key) {try {return redisTemplate.hasKey(key);} catch (Exception e) {e.printStackTrace();return false;}}public void del(String... key) {if (key ! null key.length 0) {if (key.length 1) {redisTemplate.delete(key[0]);} else {redisTemplate.delete((CollectionString) CollectionUtils.arrayToList(key));}}}// Stringpublic Object get(String key) {return key null ? null : redisTemplate.opsForValue().get(key);}public boolean set(String key, Object value) {try {redisTemplate.opsForValue().set(key, value);return true;} catch (Exception e) {e.printStackTrace();return false;}}public boolean set(String key, Object value, long time) {try {if (time 0) {redisTemplate.opsForValue().set(key, value, time, TimeUnit.SECONDS);} else {set(key, value);}return true;} catch (Exception e) {e.printStackTrace();return false;}}public long incr(String key, long delta) {if (delta 0) {throw new RuntimeException(递增因子必须大于0);}return redisTemplate.opsForValue().increment(key, delta);}public long decr(String key, long delta) {if (delta 0) {throw new RuntimeException(递减因子必须大于0);}return redisTemplate.opsForValue().increment(key, -delta);}// Mappublic Object hget(String key, String item) {return redisTemplate.opsForHash().get(key, item);}public MapObject, Object hmget(String key) {return redisTemplate.opsForHash().entries(key);}public boolean hmset(String key, MapString, Object map) {try {redisTemplate.opsForHash().putAll(key, map);return true;} catch (Exception e) {e.printStackTrace();return false;}}public boolean hmset(String key, MapString, Object map, long time) {try {redisTemplate.opsForHash().putAll(key, map);if (time 0) {expire(key, time);}return true;} catch (Exception e) {e.printStackTrace();return false;}}public boolean hset(String key, String item, Object value) {try {redisTemplate.opsForHash().put(key, item, value);return true;} catch (Exception e) {e.printStackTrace();return false;}}public boolean hset(String key, String item, Object value, long time) {try {redisTemplate.opsForHash().put(key, item, value);if (time 0) {expire(key, time);}return true;} catch (Exception e) {e.printStackTrace();return false;}}public void hdel(String key, Object... item) {redisTemplate.opsForHash().delete(key, item);}public boolean hHasKey(String key, String item) {return redisTemplate.opsForHash().hasKey(key, item);}public double hincr(String key, String item, double by) {return redisTemplate.opsForHash().increment(key, item, by);}public double hdecr(String key, String item, double by) {return redisTemplate.opsForHash().increment(key, item, -by);}// setpublic SetObject sGet(String key) {try {return redisTemplate.opsForSet().members(key);} catch (Exception e) {e.printStackTrace();return null;}}public boolean sHasKey(String key, Object value) {try {return redisTemplate.opsForSet().isMember(key, value);} catch (Exception e) {e.printStackTrace();return false;}}public long sSet(String key, Object... values) {try {return redisTemplate.opsForSet().add(key, values);} catch (Exception e) {e.printStackTrace();return 0;}}public long sSetAndTime(String key, long time, Object... values) {try {Long count redisTemplate.opsForSet().add(key, values);if (time 0) {expire(key, time);}return count;} catch (Exception e) {e.printStackTrace();return 0;}}public long sGetSetSize(String key) {try {return redisTemplate.opsForSet().size(key);} catch (Exception e) {e.printStackTrace();return 0;}}public long setRemove(String key, Object... values) {try {Long count redisTemplate.opsForSet().remove(key, values);return count;} catch (Exception e) {e.printStackTrace();return 0;}}// listpublic ListObject lGet(String key, long start, long end) {try {return redisTemplate.opsForList().range(key, start, end);} catch (Exception e) {e.printStackTrace();return null;}}public long lGetListSize(String key) {try {return redisTemplate.opsForList().size(key);} catch (Exception e) {e.printStackTrace();return 0;}}public Object lGetIndex(String key, long index) {try {return redisTemplate.opsForList().index(key, index);} catch (Exception e) {e.printStackTrace();return null;}}public boolean lSet(String key, Object value) {try {redisTemplate.opsForList().rightPush(key, value);return true;} catch (Exception e) {e.printStackTrace();return false;}}public boolean lSet(String key, Object value, long time) {try {redisTemplate.opsForList().rightPush(key, value);if (time 0) {expire(key, time);}return true;} catch (Exception e) {e.printStackTrace();return false;}}public boolean lSet(String key, ListObject value) {try {redisTemplate.opsForList().rightPushAll(key, value);return true;} catch (Exception e) {e.printStackTrace();return false;}}public boolean lSet(String key, ListObject value, long time) {try {redisTemplate.opsForList().rightPushAll(key, value);if (time 0) {expire(key, time);}return true;} catch (Exception e) {e.printStackTrace();return false;}}public boolean lUpdateIndex(String key, long index, Object value) {try {redisTemplate.opsForList().set(key, index, value);return true;} catch (Exception e) {e.printStackTrace();return false;}}public long lRemove(String key, long count, Object value) {try {Long remove redisTemplate.opsForList().remove(key, count, value);return remove;} catch (Exception e) {e.printStackTrace();return 0;}}
}2.ApplicationContextUtil
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;/*** ClassName : ApplicationContextUtil* Description : 手动获取bean的工具类*/
Component
public class ApplicationContextUtil implements ApplicationContextAware {private static ApplicationContext context;Overridepublic void setApplicationContext(ApplicationContext applicationContext) throws BeansException {this.context applicationContext;}/**** param beanName* return*/public static Object getBean(String beanName) {return context.getBean(beanName);}
}3.MybatisRedisCache
import lombok.extern.slf4j.Slf4j;
import org.apache.ibatis.cache.Cache;
import org.springframework.data.redis.connection.RedisServerCommands;
import org.springframework.data.redis.core.RedisCallback;
import org.springframework.util.DigestUtils;import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;/*** ClassName : MybatisRedisCache* Description : mybatis-plus结合redis自定义缓存管理* author ZJ*/
Slf4j
public class MybatisPlusRedisCache implements Cache {/*** 注意这里无法通过Autowired等注解的方式注入bean,只能手动获取*/private RedisUtils redisUtil;/*** 手动获取bean** return*/private void getRedisUtil() {redisUtil (RedisUtils) ApplicationContextUtil.getBean(redisUtils);}// 读写锁private final ReadWriteLock readWriteLock new ReentrantReadWriteLock(true);private String id;public MybatisPlusRedisCache(final String id) {if (id null) {throw new IllegalArgumentException(Cache instances require an ID);}log.info(二级缓存id{},id);this.id id;}Overridepublic String getId() {return this.id;}Overridepublic void putObject(Object key, Object value) {log.info(存入缓存);if (redisUtil null) {getRedisUtil();//获取bean}try {//将key加密后存入redisUtil.hset(this.id,this.MD5Encrypt(key),value);} catch (Exception e) {log.error(存入缓存失败);e.printStackTrace();}}Overridepublic Object getObject(Object key) {log.info(获取缓存);if (redisUtil null) {getRedisUtil();//获取bean}try {if (key ! null) {return redisUtil.hget(this.id,this.MD5Encrypt(key));}} catch (Exception e) {log.error(获取缓存失败);e.printStackTrace();}return null;}Overridepublic Object removeObject(Object key) {log.info(删除缓存);if (redisUtil null) {getRedisUtil();//获取bean}try {if (key ! null) {redisUtil.del(this.MD5Encrypt(key));}} catch (Exception e) {log.error(删除缓存失败);e.printStackTrace();}return null;}Overridepublic void clear() {log.info(清空缓存);if (redisUtil null) {getRedisUtil();//获取bean}try {redisUtil.del(this.id);} catch (Exception e) {log.error(清空缓存失败);e.printStackTrace();}}Overridepublic int getSize() {if (redisUtil null) {getRedisUtil();//获取bean}Long size (Long)redisUtil.execute((RedisCallbackLong) RedisServerCommands::dbSize);return size.intValue();}Overridepublic ReadWriteLock getReadWriteLock() {return this.readWriteLock;}/*** MD5加密存储key,以节约内存*/private String MD5Encrypt(Object key){String s DigestUtils.md5DigestAsHex(key.toString().getBytes());return s;}}4,编写RedisConfig配置类
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.JsonTypeInfo;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.jsontype.impl.LaissezFaireSubTypeValidator;
import lombok.extern.slf4j.Slf4j;
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
Slf4j
public class RedisConfig {/**redis配置模板**/Beanpublic RedisTemplateString, Object redisTemplate(RedisConnectionFactory factory) {//为了开发的方便一般直接使用String, ObjectRedisTemplateString, Object template new RedisTemplate();template.setConnectionFactory(factory);//json的序列化配置Jackson2JsonRedisSerializer jackson2JsonRedisSerializer new Jackson2JsonRedisSerializer(Object.class);ObjectMapper om new ObjectMapper();om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);om.activateDefaultTyping(LaissezFaireSubTypeValidator.instance ,ObjectMapper.DefaultTyping.NON_FINAL,JsonTypeInfo.As.PROPERTY);jackson2JsonRedisSerializer.setObjectMapper(om);//String的序列化StringRedisSerializer stringRedisSerializer new StringRedisSerializer();// key采用String的序列化方式template.setKeySerializer(stringRedisSerializer);// hash的key也采用String的序列化方式template.setHashKeySerializer(stringRedisSerializer);// value序列化方式采用jacksontemplate.setValueSerializer(jackson2JsonRedisSerializer);// hash的value序列化方式采用jacksontemplate.setHashValueSerializer(jackson2JsonRedisSerializer);template.afterPropertiesSet();return template;}Bean(nameredisUtils)public RedisUtils redisUtils(final RedisTemplateString, Object redisTemplate) {final RedisUtils jedisService new RedisUtils(redisTemplate);return jedisService;}}3.在Spring Boot中整合MyBatis可以通过以下步骤开启二级缓存
配置mybatis-config.xml文件 在mybatis-config.xml文件中需要添加如下配置
configurationsettingssetting namecacheEnabled valuetrue/ !-- 开启二级缓存 --setting namelazyLoadingEnabled valuetrue/ !-- 开启延迟加载 --setting nameaggressiveLazyLoading valuefalse/ !-- 关闭积极的延迟加载 --/settingstypeAliases.../typeAliasesmappers.../mappers
/configuration配置mapper.xml文件 在mapper.xml文件中需要添加如下配置
mapper namespacecom.example.myexcel.dao.InsuranceSettlementMapperresultMap typecom.example.myexcel.pojo.entity.InsuranceSettlementEntity idinsuranceSettlementMapresult propertyinsuranceName columninsurance_name/result propertycredentialNo columncredential_no/result propertydrugApplyId columndrug_apply_id/result propertytotalAmount columntotal_amount//resultMapcache-ref namespacecom.example.myexcel.dao.InsuranceSettlementMapper//mapper配置application.yml文件 在application.yml文件中需要添加如下配置
# 开启MyBatis二级缓存
mybatis-plus:mapper-locations: classpath:mapper/*.xmltype-aliases-package: com.example.myexcel.pojo.entityconfiguration:log-impl: org.apache.ibatis.logging.stdout.StdOutImpl #开启sql日志#缓存开启cache-enabled: true配置接口类 你还可以通过在mapper接口上添加CacheNamespace注解来启用并配置二级缓存。例如
Mapper
CacheNamespace(implementation MybatisPlusRedisCache.class,evictionMybatisPlusRedisCache.class)
public interface InsuranceSettlementMapper extends BaseMapperInsuranceSettlementEntity {
}配置Redis 如果使用Redis作为二级缓存的实现需要在application.yml文件中添加如下配置
# Redis配置redis:database: 15host: port: 6379password: 123456 # 密码默认为空timeout: 6000ms # 连接超时时长毫秒lettuce:pool:max-active: 1000 # 连接池最大连接数使用负值表示没有限制max-wait: -1ms # 连接池最大阻塞等待时间使用负值表示没有限制max-idle: 10 # 连接池中的最大空闲连接min-idle: 5 # 连接池中的最小空闲连接Testpublic void query(){log.info(*****************************************************************************************);ListInsuranceSettlementEntity list insuranceSettlementService.list();log.info(列表{},list);}缓存查询列表测试结果先查询缓存发现没有数据后查询数据再存入缓存 缓存查询列表测试结果先查询缓存发现有数据直接返回数据
