介绍

使用mybatis时可以使用二级缓存提高查询速度，进而改善用户体验。

使用redis做mybatis的二级缓存可是内存可控<如将单独的服务器部署出来用于二级缓存>，管理方便。

1.在pom.xml文件中引入redis依赖

<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-redis</artifactId></dependency>

2.在application.properties配置文件中进行redis的配置

## Redis spring.redis.database=0spring.redis.host=172.16.3.123spring.redis.port=6379spring.redis.password=spring.redis.pool.max-active=8spring.redis.pool.max-wait=-1spring.redis.pool.max-idle=8spring.redis.pool.min-idle=0spring.redis.timeout=0

3.创建cache包，然后创建两个类，一个ApplicationContextHolder实现ApplicationContextAware接口，具体内容如下

package com.ruijie.SpringBootandRedis.cache;import org.springframework.beans.BeansException;import org.springframework.context.ApplicationContext;import org.springframework.context.ApplicationContextAware;import org.springframework.stereotype.Component;@Componentpublic class ApplicationContextHolder implements ApplicationContextAware { private static ApplicationContext applicationContext; @Override public void setApplicationContext(ApplicationContext ctx) throws BeansException { applicationContext = ctx; } /** * Get application context from everywhere * * @return */ public static ApplicationContext getApplicationContext() { return applicationContext; } /** * Get bean by class * * @param clazz * @param <T> * @return */ public static <T> T getBean(Class<T> clazz) { return applicationContext.getBean(clazz); } /** * Get bean by class name * * @param name * @param <T> * @return */ public static <T> T getBean(String name) { return (T) applicationContext.getBean(name); }}

4.创建RedisCache类实现Cache接口，具体内容如下：

package com.ruijie.SpringBootandRedis.cache;import org.apache.ibatis.cache.Cache;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.data.redis.core.RedisCallback;import org.springframework.data.redis.core.RedisTemplate;import org.springframework.data.redis.core.ValueOperations;import java.util.concurrent.TimeUnit;import java.util.concurrent.locks.ReadWriteLock;import java.util.concurrent.locks.ReentrantReadWriteLock;public class RedisCache implements Cache { private static final Logger logger = LoggerFactory.getLogger(RedisCache.class); private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock(); private final String id; // cache instance id private RedisTemplate redisTemplate; private static final long EXPIRE_TIME_IN_MINUTES = 30; // redis过期时间 public RedisCache(String id) { if (id == null) { throw new IllegalArgumentException("Cache instances require an ID"); } this.id = id; } @Override public String getId() { return id; } /** * Put query result to redis * * @param key * @param value */ @Override public void putObject(Object key, Object value) { try { RedisTemplate redisTemplate = getRedisTemplate(); ValueOperations opsForValue = redisTemplate.opsForValue(); opsForValue.set(key, value, EXPIRE_TIME_IN_MINUTES, TimeUnit.MINUTES); logger.debug("Put query result to redis"); } catch (Throwable t) { logger.error("Redis put failed", t); } } /** * Get cached query result from redis * * @param key * @return */ @Override public Object getObject(Object key) { try { RedisTemplate redisTemplate = getRedisTemplate(); ValueOperations opsForValue = redisTemplate.opsForValue(); logger.debug("Get cached query result from redis"); System.out.println("****"+opsForValue.get(key).toString()); return opsForValue.get(key); } catch (Throwable t) { logger.error("Redis get failed, fail over to db", t); return null; } } /** * Remove cached query result from redis * * @param key * @return */ @Override @SuppressWarnings("unchecked") public Object removeObject(Object key) { try { RedisTemplate redisTemplate = getRedisTemplate(); redisTemplate.delete(key); logger.debug("Remove cached query result from redis"); } catch (Throwable t) { logger.error("Redis remove failed", t); } return null; } /** * Clears this cache instance */ @Override public void clear() { RedisTemplate redisTemplate = getRedisTemplate(); redisTemplate.execute((RedisCallback) connection -> { connection.flushDb(); return null; }); logger.debug("Clear all the cached query result from redis"); } /** * This method is not used * * @return */ @Override public int getSize() { return 0; } @Override public ReadWriteLock getReadWriteLock() { return readWriteLock; } private RedisTemplate getRedisTemplate() { if (redisTemplate == null) { redisTemplate = ApplicationContextHolder.getBean("redisTemplate"); } return redisTemplate; }}

5.实体类中要实现Serializable接口，并且要声明序列号

private static final long serialVersionUID = -2566441764189220519L;

6.开启Mybatis的二级缓存

在pom.xml配置文件中配置

mybatis.configuration.cache-enabled=true

在mapper接口中加入

@CacheNamespace(implementation=(com.demo.testdemo.cache.RedisCache.class))

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。