SpringBoot配置Redis实现mybatis的二级缓存

1.引入依赖

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

2.配置Redis的连接，开启Mybatis的缓存

spring.redis.database=0
spring.redis.host=127.0.0.1
spring.redis.port=6379
spring.redis.password=
spring.redis.pool.max-active=8
spring.redis.pool.max-wait=-1
spring.redis.pool.max-idle=8
spring.redis.pool.min-idle=0
spring.redis.timeout=0

mybatis.configuration.cache-enabled=true

3.编写RedisCache和获取bean的工具。

import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

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;

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
    @SuppressWarnings("unchecked")
    public void putObject(Object key, Object value) {
        RedisTemplate redisTemplate = getRedisTemplate();
        ValueOperations opsForValue = redisTemplate.opsForValue();
        opsForValue.set(key, value, EXPIRE_TIME_IN_MINUTES, TimeUnit.MINUTES);
        logger.debug("Put query result to redis");
    }
    /**
     * Get cached query result from redis
     *
     * @param key
     * @return
     */
    @Override
    public Object getObject(Object key) {
        RedisTemplate redisTemplate = getRedisTemplate();
        ValueOperations opsForValue = redisTemplate.opsForValue();
        logger.debug("Get cached query result from redis");
        return opsForValue.get(key);
    }
    /**
     * Remove cached query result from redis
     *
     * @param key
     * @return
     */
    @Override
    @SuppressWarnings("unchecked")
    public Object removeObject(Object key) {
        RedisTemplate redisTemplate = getRedisTemplate();
        redisTemplate.delete(key);
        logger.debug("Remove cached query result from redis");
        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");
    }
    @Override
    public int getSize() {
        return 0;
    }
    @Override
    public ReadWriteLock getReadWriteLock() {
        return readWriteLock;
    }
    private RedisTemplate getRedisTemplate() {
        if (redisTemplate == null) {
            redisTemplate = (RedisTemplate) SpringApplicationContextHolder.getBean("redisTemplate");
        }
        return redisTemplate;
    }
}

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;


@Component
public class SpringApplicationContextHolder implements ApplicationContextAware {

    // 使用一个变量接受ApplicationContext
    private static ApplicationContext ctx = null;

    @Override
    public void setApplicationContext(ApplicationContext ctx) throws BeansException {
        System.out.println(ctx);
        SpringApplicationContextHolder.ctx = ctx;
    }

    public static Object getBean(String name) {
        return ctx.getBean(name);
    }

    public static Object getBean(Class clazz) {
        return ctx.getBean(clazz);
    }
}

4.在启动类上加入注解

@EnableCaching

5.在mapper.xml配置缓存。

<mapper namespace="*****">
    <cache type="com.*****.RedisCache" />
</mapper>

type 为 第三步的编写的RedisCache类的全路径。