SpringBoot 入坑（四）2.x版本以上RedisCacheManger配置

1.springBoot 1.x 版本的RedisCacheManger配置

  @Bean
    public RedisTemplate<Object,Object> redisTemplate(
            RedisConnectionFactory redisConnectionFactory
    ){
        RedisTemplate<Object , Object> redis = new RedisTemplate<Object, Object>();
        redis.setConnectionFactory(redisConnectionFactory);
        //获取jackson序列化器
        Jackson2JsonRedisSerializer<Object> serializer = new Jackson2JsonRedisSerializer<Object>(Object.class);
        //设置序列化器
        redis.setDefaultSerializer(serializer);
        return redis;
    };

//这里可以拓展使用自定义的RedisTemplate<Object , Object > 自定义缓存
@Bean
public CacheManager cacheManager(RedisTemplate<Object,Object> redisTemplate) {
    RedisCacheManager cacheManager= new RedisCacheManager(redisTemplate);
    cacheManager.setUsePrefix(true);
  
/*   
自定义重写的话可以不用写这一段
 Map<String,Long> expiresMap=new HashMap<>();
    expiresMap.put("Product",5L);
    cacheManager.setExpires(expiresMap);
*/
    return cacheManager; //直接返回即可
}

2.springBoot 2.x 版本的CacheManger配置

 @Bean
    public CacheManager cacheManager(RedisConnectionFactory factory) {
        RedisCacheConfiguration cacheConfiguration =
                RedisCacheConfiguration.defaultCacheConfig()
                        .entryTtl(Duration.ofDays(1))
                        .disableCachingNullValues()
                        .serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(new
                                GenericJackson2JsonRedisSerializer()));
        return RedisCacheManager.builder(factory).cacheDefaults(cacheConfiguration).build();
    }

3.在jackson读取缓存时出现异常解决

at [Source: (byte[])"{"@class":"org.framwork.springbootcatchs.domain.Employee","id":1,"lastName":"aa","email":null,"gender":null,"d_id":null}"; line: 1, column: 59]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.framwork.springbootcatchs.domain.Employee` (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)
 at [Source: (byte[])"{"@class":"org.framwork.springbootcatchs.domain.Employee","id":1,"lastName":"aa","email":null,"gender":null,"d_id":null}"; line: 1, column: 59]] with root cause

com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.framwork.springbootcatchs.domain.Employee` (no Creators, like default constructor, exist): cannot deserialize from Object value (no delegate- or property-based Creator)
 at [Source: (byte[])"{"@class":"org.framwork.springbootcatchs.domain.Employee","id":1,"lastName":"aa","email":null,"gender":null,"d_id":null}"; line: 1, column: 59]
	at com.fasterxml.jackson.databind.exc.InvalidDefinitionException.from(InvalidDefinitionException.java:67) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.DeserializationContext.reportBadDefinition(DeserializationContext.java:1611) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.DatabindContext.reportBadDefinition(DatabindContext.java:400) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.DeserializationContext.handleMissingInstantiator(DeserializationContext.java:1077) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:1320) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:331) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:199) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:166) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer._deserializeTypedForId(AsPropertyTypeDeserializer.java:132) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer.deserializeTypedFromObject(AsPropertyTypeDeserializer.java:99) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.jsontype.impl.AsPropertyTypeDeserializer.deserializeTypedFromAny(AsPropertyTypeDeserializer.java:195) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.deser.std.UntypedObjectDeserializer$Vanilla.deserializeWithType(UntypedObjectDeserializer.java:710) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.deser.impl.TypeWrappedDeserializer.deserialize(TypeWrappedDeserializer.java:68) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:4482) ~[jackson-databind-2.11.0.jar:2.11.0]
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:3495) ~[jackson-databind-2.11.0.jar:2.11.0]

问题原因：
小编在该实体类中添加了一个为了方便实例化该类用的构造函数，导致JVM不会添加默认的无参构造函数，而jackson的反序列化需要无参构造函数，因此报错。

解决方法：
在实体类中补上一个无参构造器即可