【SpringBoot】SpringBoot 整合Redis缓存（十九）

　　本章介绍SpringBoot与Redis整合，对缓存不太了解的可以参考【SpringBoot】SpringBoot 缓存（十八）

　　Redis安装参考：【Redis】安装及简单使用

　　SpringBoot与Redis整合参考:【SpringBoot】SpringBoot 整合Redis

SpringBoot使用Redis做缓存

　　1、使用debug=true的模式启动项目，查看日志，发现RedisCacheConfiguration匹配上了，而默认的

　　　　

　　2、 查看RedisCacheConfiguration类，可以看到，在容器不存在CacheManager的时候，它就会自动注入了RedisCacheManager，通过前一章（【SpringBoot】SpringBoot 缓存（十八））SpringBoot缓存的学习，知道CacheManager是用来管理缓存的Cache的。其中CacheManager也是使用的JDK自动的序列化器

@Configuration
@ConditionalOnClass(RedisConnectionFactory.class)
@AutoConfigureAfter(RedisAutoConfiguration.class)
@ConditionalOnBean(RedisConnectionFactory.class)
// 条件在不存在CacheManager Bean的时候生效
@ConditionalOnMissingBean(CacheManager.class)
@Conditional(CacheCondition.class)
class RedisCacheConfiguration {

    private final CacheProperties cacheProperties;

    private final CacheManagerCustomizers customizerInvoker;

    private final org.springframework.data.redis.cache.RedisCacheConfiguration redisCacheConfiguration;

    RedisCacheConfiguration(CacheProperties cacheProperties, CacheManagerCustomizers customizerInvoker,
            ObjectProvider<org.springframework.data.redis.cache.RedisCacheConfiguration> redisCacheConfiguration) {
        this.cacheProperties = cacheProperties;
        this.customizerInvoker = customizerInvoker;
        this.redisCacheConfiguration = redisCacheConfiguration.getIfAvailable();
    }

    // 注入CacheManager
    @Bean
    public RedisCacheManager cacheManager(RedisConnectionFactory redisConnectionFactory,
            ResourceLoader resourceLoader) {
        RedisCacheManagerBuilder builder = RedisCacheManager.builder(redisConnectionFactory)
                .cacheDefaults(determineConfiguration(resourceLoader.getClassLoader()));
        List<String> cacheNames = this.cacheProperties.getCacheNames();
        if (!cacheNames.isEmpty()) {
            builder.initialCacheNames(new LinkedHashSet<>(cacheNames));
        }
        return this.customizerInvoker.customize(builder.build());
    }

    private org.springframework.data.redis.cache.RedisCacheConfiguration determineConfiguration(
            ClassLoader classLoader) {
        if (this.redisCacheConfiguration != null) {
            return this.redisCacheConfiguration;
        }
        Redis redisProperties = this.cacheProperties.getRedis();
        org.springframework.data.redis.cache.RedisCacheConfiguration config = org.springframework.data.redis.cache.RedisCacheConfiguration
                .defaultCacheConfig();
        config = config.serializeValuesWith(
                // 使用默认的JDK序列化器
                SerializationPair.fromSerializer(new JdkSerializationRedisSerializer(classLoader)));
        if (redisProperties.getTimeToLive() != null) {
            config = config.entryTtl(redisProperties.getTimeToLive());
        }
        if (redisProperties.getKeyPrefix() != null) {
            config = config.prefixKeysWith(redisProperties.getKeyPrefix());
        }
        if (!redisProperties.isCacheNullValues()) {
            config = config.disableCachingNullValues();
        }
        if (!redisProperties.isUseKeyPrefix()) {
            config = config.disableKeyPrefix();
        }
        return config;
    }

}

　　3、测试缓存，使用@Cacheable标签，如下，调用getEmp方法，查看缓存内容

@Cacheable(cacheNames="emp", key = "emp#id" /*keyGenerator = "myKeyGenerator"*/)
public Employee getEmp(Integer id){
    System.out.println("===查询" + id + "号员工");
    return employeeMapper.getEmpById(id);
}

　　　　缓存内容如下，存储的也是emp对象的序列化结果

　　　　

　　4、自己注入一个CacheManager的Bean，并且使用json序列化的方式

/**
 * 缓存管理器
 */
@Bean
public CacheManager cacheManager(RedisConnectionFactory redisConnectionFactory) {

    //初始化一个RedisCacheWriter
    RedisCacheWriter redisCacheWriter = RedisCacheWriter.nonLockingRedisCacheWriter(redisConnectionFactory);

    //设置CacheManager的值序列化方式为json序列化
    RedisSerializer<Object> jsonSerializer = new Jackson2JsonRedisSerializer<Object>(Object.class);
    RedisSerializationContext.SerializationPair<Object> pair = RedisSerializationContext.SerializationPair
            .fromSerializer(jsonSerializer);
    RedisCacheConfiguration defaultCacheConfig=RedisCacheConfiguration.defaultCacheConfig()
            .serializeValuesWith(pair);

    //设置默认超过期时间是30秒
    defaultCacheConfig.entryTtl(Duration.ofSeconds(30));
    //初始化RedisCacheManager
    return new RedisCacheManager(redisCacheWriter, defaultCacheConfig);

} 

　　5、测试缓存，使用@Cacheable标签，如下，测试时，先将原有缓存情况，避免影响测试，调用getEmp方法，查看缓存内容