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

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<!-- 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

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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

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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

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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

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

四、在DAO类添加该注解

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@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

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@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

文章目录
  1. 1. 一、添加Maven依赖
  2. 2. 二、编写Redis相关类
  3. 3. 三、yml配置redis
  4. 4. 四、在DAO类添加该注解
  5. 5. 五、实现类或者在Controller加如下代码,键值对保存对应的数据
  6. 6. 六、如何确保Redis数据实时更新