SpringBoot+MyBatis+Redis(二级缓存)

应用场景:
保存大数据量，避免重复请求。

一、添加Maven依赖

<!-- SpringBoot Boot Redis -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

二、编写Redis相关类

RedisService.java

import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.TimeUnit;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.HashOperations;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.ValueOperations;
import org.springframework.stereotype.Component;

@SuppressWarnings(value = { "unchecked", "rawtypes" })
@Component
public class RedisService
{
    @Autowired
    public RedisTemplate redisTemplate;

    /**
     * 缓存基本的对象，Integer、String、实体类等
     *
     * @param key 缓存的键值
     * @param value 缓存的值
     */
    public <T> void setCacheObject(final String key, final T value)
    {
        redisTemplate.opsForValue().set(key, value);
    }

    /**
     * 缓存基本的对象，Integer、String、实体类等
     *
     * @param key 缓存的键值
     * @param value 缓存的值
     * @param timeout 时间
     * @param timeUnit 时间颗粒度
     */
    public <T> void setCacheObject(final String key, final T value, final Integer timeout, final TimeUnit timeUnit)
    {
        redisTemplate.opsForValue().set(key, value, timeout, timeUnit);
    }

    /**
     * 设置有效时间
     *
     * @param key Redis键
     * @param timeout 超时时间
     * @return true=设置成功；false=设置失败
     */
    public boolean expire(final String key, final long timeout)
    {
        return expire(key, timeout, TimeUnit.SECONDS);
    }

    /**
     * 设置有效时间
     *
     * @param key Redis键
     * @param timeout 超时时间
     * @param unit 时间单位
     * @return true=设置成功；false=设置失败
     */
    public boolean expire(final String key, final long timeout, final TimeUnit unit)
    {
        return redisTemplate.expire(key, timeout, unit);
    }

    /**
     * 获得缓存的基本对象。
     *
     * @param key 缓存键值
     * @return 缓存键值对应的数据
     */
    public <T> T getCacheObject(final String key)
    {
        ValueOperations<String, T> operation = redisTemplate.opsForValue();
        return operation.get(key);
    }

    /**
     * 删除单个对象
     *
     * @param key
     */
    public boolean deleteObject(final String key)
    {
        return redisTemplate.delete(key);
    }

    /**
     * 删除集合对象
     *
     * @param collection 多个对象
     * @return
     */
    public long deleteObject(final Collection collection)
    {
        return redisTemplate.delete(collection);
    }

    /**
     * 缓存List数据
     *
     * @param key 缓存的键值
     * @param dataList 待缓存的List数据
     * @return 缓存的对象
     */
    public <T> long setCacheList(final String key, final List<T> dataList)
    {
        Long count = redisTemplate.opsForList().rightPushAll(key, dataList);
        return count == null ? 0 : count;
    }

    /**
     * 获得缓存的list对象
     *
     * @param key 缓存的键值
     * @return 缓存键值对应的数据
     */
    public <T> List<T> getCacheList(final String key)
    {
        return redisTemplate.opsForList().range(key, 0, -1);
    }

    /**
     * 缓存Set
     *
     * @param key 缓存键值
     * @param dataSet 缓存的数据
     * @return 缓存数据的对象
     */
    public <T> long setCacheSet(final String key, final Set<T> dataSet)
    {
        Long count = redisTemplate.opsForSet().add(key, dataSet);
        return count == null ? 0 : count;
    }

    /**
     * 获得缓存的set
     *
     * @param key
     * @return
     */
    public <T> Set<T> getCacheSet(final String key)
    {
        return redisTemplate.opsForSet().members(key);
    }

    /**
     * 缓存Map
     *
     * @param key
     * @param dataMap
     */
    public <T> void setCacheMap(final String key, final Map<String, T> dataMap)
    {
        if (dataMap != null) {
            redisTemplate.opsForHash().putAll(key, dataMap);
        }
    }

    /**
     * 获得缓存的Map
     *
     * @param key
     * @return
     */
    public <T> Map<String, T> getCacheMap(final String key)
    {
        return redisTemplate.opsForHash().entries(key);
    }

    /**
     * 往Hash中存入数据
     *
     * @param key Redis键
     * @param hKey Hash键
     * @param value 值
     */
    public <T> void setCacheMapValue(final String key, final String hKey, final T value)
    {
        redisTemplate.opsForHash().put(key, hKey, value);
    }

    /**
     * 获取Hash中的数据
     *
     * @param key Redis键
     * @param hKey Hash键
     * @return Hash中的对象
     */
    public <T> T getCacheMapValue(final String key, final String hKey)
    {
        HashOperations<String, String, T> opsForHash = redisTemplate.opsForHash();
        return opsForHash.get(key, hKey);
    }

    /**
     * 获取多个Hash中的数据
     *
     * @param key Redis键
     * @param hKeys Hash键集合
     * @return Hash对象集合
     */
    public <T> List<T> getMultiCacheMapValue(final String key, final Collection<Object> hKeys)
    {
        return redisTemplate.opsForHash().multiGet(key, hKeys);
    }

    /**
     * 获得缓存的基本对象列表
     * 
     * @param pattern 字符串前缀
     * @return 对象列表
     */
    public Collection<String> keys(final String pattern)
    {
        return redisTemplate.keys(pattern);
    }
}

RedisConfig.java

import org.springframework.cache.annotation.CachingConfigurerSupport;
import org.springframework.cache.annotation.EnableCaching;
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.StringRedisSerializer;
import com.fasterxml.jackson.annotation.JsonAutoDetect;
import com.fasterxml.jackson.annotation.PropertyAccessor;
import com.fasterxml.jackson.databind.ObjectMapper;
@Configuration
@EnableCaching
public class RedisConfig extends CachingConfigurerSupport
{
    @Bean
    @SuppressWarnings(value = { "unchecked", "rawtypes", "deprecation" })
    public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory connectionFactory)
    {
        RedisTemplate<Object, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(connectionFactory);

        FastJson2JsonRedisSerializer serializer = new FastJson2JsonRedisSerializer(Object.class);

        ObjectMapper mapper = new ObjectMapper();
        mapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        mapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        serializer.setObjectMapper(mapper);

        template.setValueSerializer(serializer);
        // 使用StringRedisSerializer来序列化和反序列化redis的key值
        template.setKeySerializer(new StringRedisSerializer());
        template.afterPropertiesSet();
        return template;
    }
}

RedisCache.java

import org.apache.ibatis.cache.Cache;
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 final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();
    private final String id;
    private RedisTemplate redisTemplate;
    //redis过期时间
    private static final long EXPIRE_TIME_IN_MINUTES = 30;

    public RedisCache(String id) {
        if (id == null) {
            throw new IllegalArgumentException("Cache instance required 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) {
        RedisTemplate redisTemplate = getRedisTemplate();
        ValueOperations opsForValue = redisTemplate.opsForValue();
        System.out.println(key + ": key");
        System.out.println(key.toString() + ": key.toString()");
        System.out.println(value + ": value");
        System.out.println(value.toString() + ": value.toString()");
        opsForValue.set(key.toString(), value, EXPIRE_TIME_IN_MINUTES, TimeUnit.MINUTES);
        System.out.println("结果成功放入缓存 and " + "key = " + "\n" + key + "value = " + value);
        System.out.println(opsForValue.get(key.toString()));
    }

    /**
     * Get cached query result to redis
     *
     * @Param key
     * @Return
     */
    @Override
    public Object getObject(Object key) {
        RedisTemplate redisTemplate = getRedisTemplate();
//        redisTemplate.setHashValueSerializer(new StringRedisSerializer());
        ValueOperations opsForValue = redisTemplate.opsForValue();
        System.out.println("结果从缓存中获取");
        return opsForValue.get(key.toString());
    }

    /**
     * Remove cached query result to redis
     *
     * @Param key
     * @Return
     */
    @Override
    public Object removeObject(Object key) {
        RedisTemplate redisTemplate = getRedisTemplate();
        redisTemplate.delete(key);
        System.out.println("从缓存中删除");
        return null;
    }

    /**
     * Clear this cache instance
     */
    @Override
    public void clear() {
        RedisTemplate redisTemplate = getRedisTemplate();
        redisTemplate.execute((RedisCallback) connection -> {
            connection.flushDb();
            return null;
        });
        System.out.println("清空缓存");
    }

    @Override
    public int getSize() {
        Long size = (Long) redisTemplate.execute((RedisCallback) connection -> connection.dbSize());
        return size.intValue();
    }

    @Override
    public ReadWriteLock getReadWriteLock() {
        return readWriteLock;
    }

    private RedisTemplate getRedisTemplate() {
        if (redisTemplate == null) {
            redisTemplate = ApplicationContextHolder.getBean("redisTemplate");
        }
        return redisTemplate;
    }
}

三、yml配置redis

spring:
  redis:
    host: localhost
    port: 6379
    password:

四、在DAO类添加该注解

@CacheNamespace(implementation = RedisCache.class)

五、实现类或者在Controller加如下代码，键值对保存对应的数据

@Autowired
private RedisService redisService;

六、如何确保Redis数据实时更新

我研究了下，通常如下:
1.先删缓存，再更新数据库
2.先写数据库，再删缓存
参考:
Redis缓存如何保证一致性

补充:
Redis 和 Mysql 数据库数据如何保持一致性