一、前言
关于EnableCaching最简单使用，个人感觉只需提供一个CacheManager的一个实例就好了。springboot为我们提供了cache相关的自动配置。引入cache模块，如下。
二、maven依赖
<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-cache</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-redis</artifactId></dependency><dependency><groupId>org.springframework.integration</groupId><artifactId>spring-integration-redis</artifactId></dependency><dependency><groupId>redis.clients</groupId><artifactId>jedis</artifactId></dependency>
三、缓存类型
本人也仅仅使用了redis、guava、ehcache。更多详情请参考 spring cache官方文档。
https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-caching.html
四、常用注解
@Cacheable 触发缓存填充
@CacheEvict 触发缓存驱逐
@CachePut 更新缓存而不会干扰方法执行
@Caching 重新组合要在方法上应用的多个缓存操作
@CacheConfig 在类级别共享一些常见的缓存相关设置
五、Spring Cache提供的SpEL上下文数据
下表直接摘自Spring官方文档：
| 名字 | 位置 | 描述 | 示例 |
| methodName | root对象 | 当前被调用的方法名 | #root.methodName |
| method | root对象 | 当前被调用的方法 | #root.method.name |
| target | root对象 | 当前被调用的目标对象 | #root.target |
| targetClass | root对象 | 当前被调用的目标对象类 | #root.targetClass |
| args | root对象 | 当前被调用的方法的参数列表 | #root.args[0] |
| caches | root对象 | 当前方法调用使用的缓存列表（如@Cacheable(value={"cache1", "cache2"})），则有两个cache | #root.caches[0].name |
| argument name | 执行上下文 | 当前被调用的方法的参数，如findById(Long id)，我们可以通过#id拿到参数 | #user.id |
| result | 执行上下文 | 方法执行后的返回值（仅当方法执行之后的判断有效，如‘unless’，'cache evict'的beforeInvocation=false） | #result |
六、RedisCacheManager配置
基于jedis
@Configuration
@EnableCaching public class RedisCacheConfig extends CachingConfigurerSupport {@Autowiredprivate RedisProperties redisProperties;@Beanpublic JedisConnectionFactory jedisConnectionFactory() {// 获取服务器数组(这里要相信自己的输入，所以没有考虑空指针问题)String[] serverArray = redisProperties.getClusterNodes().split(",");RedisClusterConfiguration redisClusterConfiguration = new RedisClusterConfiguration(Arrays.asList(serverArray));JedisPoolConfig jedisPoolConfig = new JedisPoolConfig();// 最大空闲连接数, 默认8个jedisPoolConfig.setMaxIdle(100);// 最大连接数, 默认8个jedisPoolConfig.setMaxTotal(500);// 最小空闲连接数, 默认0jedisPoolConfig.setMinIdle(0);// 获取连接时的最大等待毫秒数(如果设置为阻塞时BlockWhenExhausted),如果超时就抛异常, 小于零:阻塞不确定的时间,// 默认-1jedisPoolConfig.setMaxWaitMillis(2000); // 设置2秒// 对拿到的connection进行validateObject校验jedisPoolConfig.setTestOnBorrow(true);return new JedisConnectionFactory(redisClusterConfiguration,jedisPoolConfig);}/** * 注入redis template * * @return */@Bean@Qualifier("redisTemplate")public RedisTemplate redisTemplate(JedisConnectionFactoryjedisConnectionFactory, Jackson2JsonRedisSerializer jackson2JsonRedisSerializer) {RedisTemplate template = new RedisTemplate();template.setConnectionFactory(jedisConnectionFactory);template.setKeySerializer(new JdkSerializationRedisSerializer());template.setValueSerializer(jackson2JsonRedisSerializer);template.afterPropertiesSet();return template;}/** * redis cache manager * * @return */@Bean@Primarypublic RedisCacheManager redisCacheManager(JedisConnectionFactory jedisConnectionFactory, ObjectProvider<List<RedisCacheConfigurationProvider>> configurationProvider) {Map<String, RedisCacheConfiguration> redisCacheConfigurationMap = Maps.newHashMap();List<RedisCacheConfigurationProvider> configurations= configurationProvider.getIfAvailable();if (!CollectionUtils.isEmpty(configurations)) {for (RedisCacheConfigurationProvider configuration : configurations) {redisCacheConfigurationMap.putAll(configuration.resolve());}}RedisCacheManager cacheManager = RedisCacheManager.RedisCacheManagerBuilder.fromConnectionFactory(jedisConnectionFactory).cacheDefaults(resovleRedisCacheConfiguration(Duration.ofSeconds(300), JacksonHelper.genJavaType(Object.class))).withInitialCacheConfigurations(redisCacheConfigurationMap).build();return cacheManager;}private static RedisCacheConfiguration resovleRedisCacheConfiguration(Duration duration, JavaType javaType) {return RedisCacheConfiguration.defaultCacheConfig().serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(new StringRedisSerializer())).serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(new Jackson2JsonRedisSerializer<>(javaType))).entryTtl(duration);}/** * 配置一个序列器, 将对象序列化为字符串存储, 和将对象反序列化为对象 */@Beanpublic Jackson2JsonRedisSerializer jackson2JsonRedisSerializer() {Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);ObjectMapper om = new ObjectMapper();om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);jackson2JsonRedisSerializer.setObjectMapper(om);return jackson2JsonRedisSerializer;}public static abstract class RedisCacheConfigurationProvider {// key = 缓存名称， value = 缓存时间 和 缓存类型protected Map<String, Pair<Duration, JavaType>> configs;protected abstract void initConfigs();public Map<String, RedisCacheConfiguration> resolve() {initConfigs();Assert.notEmpty(configs, "RedisCacheConfigurationProvider 配置不能为空...");Map<String, RedisCacheConfiguration> result = Maps.newHashMap();configs.forEach((cacheName, pair) -> result.put(cacheName, resovleRedisCacheConfiguration(pair.getKey(), pair.getValue())));return result;}}}
基于Lettuce
@Configuration @EnableCaching public class RedisCacheConfig extends CachingConfigurerSupport {@Autowiredprivate RedisProperties redisProperties;@Beanpublic LettuceConnectionFactory lettuceConnectionFactory() {String[] serverArray = redisProperties.getClusterNodes().split(",");// 获取服务器数组(这里要相信自己的输入，所以没有考虑空指针问题)RedisClusterConfiguration redisClusterConfiguration = new RedisClusterConfiguration(Arrays.asList(serverArray));GenericObjectPoolConfig poolConfig = new GenericObjectPoolConfig();// 最大空闲连接数, 默认8个poolConfig.setMaxIdle(100);// 最大连接数, 默认8个poolConfig.setMaxTotal(500);// 最小空闲连接数, 默认0poolConfig.setMinIdle(0);LettuceClientConfiguration lettuceClientConfiguration = LettucePoolingClientConfiguration.builder().commandTimeout(Duration.ofSeconds(15)).poolConfig(poolConfig).shutdownTimeout(Duration.ZERO).build();return new LettuceConnectionFactory(redisClusterConfiguration, lettuceClientConfiguration);}/** * 注入redis template * * @return */@Bean@Qualifier("redisTemplate")public RedisTemplate redisTemplate(LettuceConnectionFactory lettuceConnectionFactory, Jackson2JsonRedisSerializer jackson2JsonRedisSerializer) {RedisTemplate template = new RedisTemplate();template.setConnectionFactory(lettuceConnectionFactory);template.setKeySerializer(new JdkSerializationRedisSerializer());template.setValueSerializer(jackson2JsonRedisSerializer);template.afterPropertiesSet();return template;}/** * redis cache manager * * @return */@Bean@Primarypublic RedisCacheManager redisCacheManager(LettuceConnectionFactory lettuceConnectionFactory, ObjectProvider<List<RedisCacheConfigurationProvider>> configurationProvider) {Map<String, RedisCacheConfiguration> redisCacheConfigurationMap = Maps.newHashMap();List<RedisCacheConfigurationProvider> configurations = configurationProvider.getIfAvailable();if (!CollectionUtils.isEmpty(configurations)) {for (RedisCacheConfigurationProvider configuration : configurations) {redisCacheConfigurationMap.putAll(configuration.resolve());}}RedisCacheManager cacheManager = RedisCacheManager.RedisCacheManagerBuilder.fromConnectionFactory(lettuceConnectionFactory).cacheDefaults(resovleRedisCacheConfiguration(Duration.ofSeconds(300), JacksonHelper.genJavaType(Object.class))).withInitialCacheConfigurations(redisCacheConfigurationMap).build();return cacheManager;}private static RedisCacheConfiguration resovleRedisCacheConfiguration(Duration duration, JavaType javaType) {return RedisCacheConfiguration.defaultCacheConfig().serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(new StringRedisSerializer())).serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(new Jackson2JsonRedisSerializer<>(javaType))).entryTtl(duration);}@Beanpublic RedisLockRegistry redisLockRegistry(LettuceConnectionFactory lettuceConnectionFactory) {return new RedisLockRegistry(lettuceConnectionFactory, "recharge-plateform", 60000 * 20);}/** * 配置一个序列器, 将对象序列化为字符串存储, 和将对象反序列化为对象 */@Beanpublic Jackson2JsonRedisSerializer jackson2JsonRedisSerializer() {Jackson2JsonRedisSerializer jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer(Object.class);ObjectMapper om = new ObjectMapper();om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);jackson2JsonRedisSerializer.setObjectMapper(om);return jackson2JsonRedisSerializer;}public static abstract class RedisCacheConfigurationProvider {// key = 缓存名称， value = 缓存时间 和 缓存类型protected Map<String, Pair<Duration, JavaType>> configs;protected abstract void initConfigs();public Map<String, RedisCacheConfiguration> resolve() {initConfigs();Assert.notEmpty(configs, "RedisCacheConfigurationProvider 配置不能为空...");Map<String, RedisCacheConfiguration> result = Maps.newHashMap();configs.forEach((cacheName, pair) -> result.put(cacheName, resovleRedisCacheConfiguration(pair.getKey(), pair.getValue())));return result;}}}
Jedis和Lettuce比较
Jedis 是直连模式，在多个线程间共享一个 Jedis 实例时是线程不安全的，如果想要在多线程环境下使用 Jedis，需要使用连接池，
每个线程都去拿自己的 Jedis 实例，当连接数量增多时，物理连接成本就较高了。
Lettuce的连接是基于Netty的，连接实例可以在多个线程间共享，
所以，一个多线程的应用可以使用同一个连接实例，而不用担心并发线程的数量。当然这个也是可伸缩的设计，一个连接实例不够的情况也可以按需增加连接实例。通过异步的方式可以让我们更好的利用系统资源，而不用浪费线程等待网络或磁盘I/O。
只在基于Lettuce的配置中，加入了RedisLockRegistry对应bean的配置，由于在集群的模式下，基于Jedis的配置下，通过RedisLockRegistry 获取分布式锁的时候报错：
EvalSha is not supported in cluster environment
具体的解决方案就是切换至基于Lettuce的配置，请参考
https://stackoverflow.com/questions/47092475/spring-boot-redistemplate-execute-sc
RedisCacheConfigurationProvider 作用为不同的cache提供特定的缓存时间以及key、value序列化和反序列化的方式。具体使用方式如下。
@Componentpublic class CouponRedisCacheConfigurationProvider extends RedisCacheConfig.RedisCacheConfigurationProvider {@Overrideprotected void initConfigs() {this.configs = Maps.newHashMap();this.configs.put(CouponConstants.COUPON_ALL_CACHE, new Pair<>(Duration.ofHours(1), JacksonHelper.genMapType(HashMap.class, Integer.class, Coupon.class)));this.configs.put(CouponConstants.COUPON_GOOD_CACHE, new Pair<>(Duration.ofHours(1), JacksonHelper.genCollectionType(List.class, String.class)));this.configs.put(CouponConstants.COUPON_HANDLE_TELEPHONE_STATUS_CACHE, new Pair<>(Duration.ofMinutes(10), JacksonHelper.genCollectionType(List.class, CouponHandle.class)));this.configs.put(CouponConstants.COUPON_HANDLE_TELEPHONE_GOOD_CACHE, new Pair<>(Duration.ofMinutes(10), JacksonHelper.genCollectionType(List.class, CouponHandle.class)));}}
JacksonHelper 作用是根据不同的类型的对象获取对应的JavaType对象，在构造RedisTempalte序列化和反序列化器Jackson2JsonRedisSerializer对象需要。具体代码如下。
public class JacksonHelper {private static Logger LOGGER = LoggerFactory.getLogger(JacksonHelper.class);private static final SimpleModule module = initModule();private static final ObjectMapper objectMapper;private static final ObjectMapper prettyMapper;public JacksonHelper() {}private static SimpleModule initModule() {return (new SimpleModule()).addSerializer(BigDecimal.class, new BigDecimalSerializer()).addSerializer(LocalTime.class, new LocalTimeSerializer()).addDeserializer(LocalTime.class, new LocalTimeDeserializer()).addSerializer(LocalDate.class, new LocalDateSerializer()).addDeserializer(LocalDate.class, new LocalDateDeserializer()).addSerializer(LocalDateTime.class, new LocalDateTimeSerializer()).addDeserializer(LocalDateTime.class, new LocalDateTimeDeserializer()).addSerializer(Date.class, new DateSerializer()).addDeserializer(Date.class, new DateDeserializer());}public static JavaType genJavaType(TypeReference<?> typeReference) {return getObjectMapper().getTypeFactory().constructType(typeReference.getType());}public static JavaType genJavaType(Class<?> clazz) {return getObjectMapper().getTypeFactory().constructType(clazz);}public static JavaType genCollectionType(Class<? extends Collection> collectionClazz, Class<?> javaClazz) {return getObjectMapper().getTypeFactory().constructCollectionType(collectionClazz, javaClazz);}public static JavaType genMapType(Class<? extends Map> mapClazz, Class<?> keyClass, Class<?> valueClazz) {return getObjectMapper().getTypeFactory().constructMapType(mapClazz, keyClass, valueClazz);}public static ObjectMapper getObjectMapper() {return objectMapper;}public static ObjectMapper getPrettyMapper() {return prettyMapper;}static {objectMapper = (new ObjectMapper()).registerModule(module).configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false).configure(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL, true).configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);prettyMapper = objectMapper.copy().configure(SerializationFeature.INDENT_OUTPUT, true);}}class LocalDateDeserializer extends JsonDeserializer<LocalDate> {public LocalDateDeserializer() {}public LocalDate deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {String dateString = ((JsonNode) jp.getCodec().readTree(jp)).asText();return LocalDate.parse(dateString, DateTimeFormatter.ISO_LOCAL_DATE);}}class DateDeserializer extends JsonDeserializer<Date> {public DateDeserializer() {}public Date deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {String dateTimeStr = ((JsonNode) jp.getCodec().readTree(jp)).asText();SimpleDateFormat sdf = new SimpleDateFormat(CouponConstants.DATE_TIME_FORMATER);ParsePosition pos = new ParsePosition(0);return sdf.parse(dateTimeStr, pos);}}class LocalDateTimeDeserializer extends JsonDeserializer<LocalDateTime> {public LocalDateTimeDeserializer() {}public LocalDateTime deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {String dateTimeStr = ((JsonNode) jp.getCodec().readTree(jp)).asText();return LocalDateTime.parse(dateTimeStr, DateTimeFormatter.ISO_LOCAL_DATE_TIME);}}class LocalTimeDeserializer extends JsonDeserializer<LocalTime> {public LocalTimeDeserializer() {}public LocalTime deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {String dateString = ((JsonNode) jp.getCodec().readTree(jp)).asText();return LocalTime.parse(dateString, DateTimeFormatter.ISO_LOCAL_TIME);}}class BigDecimalSerializer extends JsonSerializer<BigDecimal> {public BigDecimalSerializer() {}public void serialize(BigDecimal value, JsonGenerator jgen, SerializerProvider provider) throws IOException {jgen.writeString(value.toString());}}class LocalDateSerializer extends JsonSerializer<LocalDate> {public LocalDateSerializer() {}public void serialize(LocalDate value, JsonGenerator jgen, SerializerProvider provider) throws IOException {jgen.writeString(DateTimeFormatter.ISO_LOCAL_DATE.format(value));}}class LocalDateTimeSerializer extends JsonSerializer<LocalDateTime> {public LocalDateTimeSerializer() {}public void serialize(LocalDateTime value, JsonGenerator jgen, SerializerProvider provider) throws IOException {jgen.writeString(DateTimeFormatter.ISO_LOCAL_DATE_TIME.format(value));}}class DateSerializer extends JsonSerializer<Date> {public DateSerializer() {}public void serialize(Date value, JsonGenerator jgen, SerializerProvider provider) throws IOException {SimpleDateFormat sdf = new SimpleDateFormat(CouponConstants.DATE_TIME_FORMATER);jgen.writeString(sdf.format(value));}}class LocalTimeSerializer extends JsonSerializer<LocalTime> {public LocalTimeSerializer() {}public void serialize(LocalTime value, JsonGenerator jgen, SerializerProvider provider) throws IOException {jgen.writeString(DateTimeFormatter.ISO_LOCAL_TIME.format(value));}}
业务代码
@Component public class ServiceImpl { @Override@CacheEvict(cacheNames = CouponConstants.COUPON_HANDLE_TELEPHONE_STATUS_CACHE, key = "#telephone+'#'+#status", beforeInvocation = true)public void evictCouponHandles(String telephone, Integer status) {}@Override@Cacheable(cacheNames = CouponConstants.COUPON_HANDLE_TELEPHONE_STATUS_CACHE, key = "#telephone+'#'+#status", sync = true)public List<CouponHandle> searchCouponHandles(String telephone, Integer status) {}}
不同的缓存对应不同的存储类型，不同的存储类型对应着不同的序列化和反序列化器，这就保证了再调用注有@Cacheable注解的代码时获取到的对象不会发生类型转换错误。关于设置不同的cache下过期时间以及序列化和反序列器，请参考下面更直接明了的例子。
@Configurationpublic class RedisCacheConfig {@Beanpublic KeyGenerator simpleKeyGenerator() {return (o, method, objects) -> {StringBuilder stringBuilder = new StringBuilder();stringBuilder.append(o.getClass().getSimpleName());stringBuilder.append(".");stringBuilder.append(method.getName());stringBuilder.append("[");for (Object obj : objects) {stringBuilder.append(obj.toString());}stringBuilder.append("]");return stringBuilder.toString();};}@Beanpublic CacheManager cacheManager(RedisConnectionFactory redisConnectionFactory) {return new RedisCacheManager(RedisCacheWriter.nonLockingRedisCacheWriter(redisConnectionFactory),this.getRedisCacheConfigurationWithTtl(600), // 默认策略，未配置的 cache 会使用这个this.getRedisCacheConfigurationMap() // 指定 cache 策略 );}private Map<String, RedisCacheConfiguration> getRedisCacheConfigurationMap() {Map<String, RedisCacheConfiguration> redisCacheConfigurationMap = new HashMap<>();redisCacheConfigurationMap.put("UserInfoList", this.getRedisCacheConfigurationWithTtl(3000));redisCacheConfigurationMap.put("UserInfoListAnother", this.getRedisCacheConfigurationWithTtl(18000));return redisCacheConfigurationMap;}private RedisCacheConfiguration getRedisCacheConfigurationWithTtl(Integer seconds) {Jackson2JsonRedisSerializer<Object> jackson2JsonRedisSerializer = new Jackson2JsonRedisSerializer<>(Object.class);ObjectMapper om = new ObjectMapper();om.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);om.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);jackson2JsonRedisSerializer.setObjectMapper(om);RedisCacheConfiguration redisCacheConfiguration = RedisCacheConfiguration.defaultCacheConfig();redisCacheConfiguration = redisCacheConfiguration.serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(jackson2JsonRedisSerializer)).entryTtl(Duration.ofSeconds(seconds));return redisCacheConfiguration;}}
@Cacheable(value = "UserInfoList", keyGenerator = "simpleKeyGenerator") // 3000秒 @Cacheable(value = "UserInfoListAnother", keyGenerator = "simpleKeyGenerator") // 18000秒 @Cacheable(value = "DefaultKeyTest", keyGenerator = "simpleKeyGenerator") // 600秒，未指定的cache，使用默认策略
