Spring-Boot2-X集成Redis做缓存

实战出真知，作文以记之。

解决的主要痛点

• 以SpringBoot2.0.2为背景
• 通用的序列化和反序列化设置
  使用Jackson2JsonRedisSerializer进行序列化与反序列化。
• 解决缓存中的乱码问题
• 详细的使用说明
• 齐全的使用示例

创建Spring Boot工程

略，详细步骤可参考使用STS创建Spring Boot 项目。

添加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>redis.clients</groupId>
  <artifactId>jedis</artifactId>
</dependency>
<dependency>
  <groupId>com.fasterxml.jackson.core</groupId>
  <artifactId>jackson-core</artifactId>
</dependency>

Redis的配置参数

在application.properties中加入以下配置参数

# 缓存时长，单位秒
cache.default-exp=72
# 数据库设置
spring.redis.database=0
# 宿主机IP
spring.redis.host=127.0.0.1
# 端口号
spring.redis.port=6379
# 密码
spring.redis.password=redis
# 连接超时时间 单位 ms（毫秒）
spring.redis.timeout=3000
# 连接池中的最大空闲连接，默认值也是8
spring.redis.lettuce.pool.max-idle=100
# 连接池中的最小空闲连接，默认值也是0
spring.redis.lettuce.pool.min-idle=50
# 如果赋值为-1，则表示不限制
spring.redis.lettuce.pool.max-wait=2000

使用注解配置Redis

创建一个名为RedisConfig的class并继承CachingConfigurerSupport，注意需要在class上添加@Configuration和@EnableCaching注解。

import java.lang.reflect.Method;
import java.time.Duration;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.cache.CacheManager;
import org.springframework.cache.annotation.CachingConfigurerSupport;
import org.springframework.cache.annotation.EnableCaching;
import org.springframework.cache.interceptor.KeyGenerator;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.cache.RedisCacheConfiguration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.Jackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.RedisSerializationContext;
import org.springframework.data.redis.serializer.RedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;
import com.alibaba.fastjson.JSON;
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 {

    @Value("${cache.default-exp}")
    private long exps;

    @Value("${spring.redis.host}")
    private String host;

    @Value("${spring.redis.port}")
    private int port;

    @Value("${spring.redis.timeout}")
    private int timeout;

    @Value("${spring.redis.password}")
    private String password;

    @Value("${spring.redis.lettuce.pool.min-idle}")
    private int minIdle;

    @Value("${spring.redis.lettuce.pool.max-idle}")
    private int maxIdle;

    @Value("${spring.redis.lettuce.pool.max-wait}")
    private long maxWaitMillis;

    @Bean
    public KeyGenerator keyGenerator() {
        return new KeyGenerator() {
            @Override
            public Object generate(Object target, Method method, Object... params) {
                StringBuffer sb = new StringBuffer();
                sb.append(target.getClass().getName());
                sb.append(method.getName());
                for (Object obj : params) {
                    sb.append(obj.toString());
                }
                return sb.toString();
            }
        };
    }

    /**
     * RedisTemplate配置
     *
     * @param redisConnectionFactory
     * @return
     */
    @Bean
    public RedisTemplate<?, ?> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
        RedisTemplate<Object, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(redisConnectionFactory);
        // 使用Jackson2JsonRedisSerializer来序列化和反序列化redis的value值
        Jackson2JsonRedisSerializer<JSON> serializer = new Jackson2JsonRedisSerializer<JSON>(JSON.class);
        ObjectMapper mapper = new ObjectMapper();
        mapper.setVisibility(PropertyAccessor.ALL, JsonAutoDetect.Visibility.ANY);
        mapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
        serializer.setObjectMapper(mapper);
        template.setValueSerializer(serializer);
        template.setHashValueSerializer(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;
    }

    @Bean
    public CacheManager cacheManager(RedisConnectionFactory redisConnectionFactory) {
        // 生成一个默认配置，通过config对象即可对缓存进行自定义配置
        RedisSerializer<String> redisSerializer = new StringRedisSerializer();
        // 使用Jackson2JsonRedisSerializer来序列化和反序列化redis的value值
        Jackson2JsonRedisSerializer<JSON> serializer = new Jackson2JsonRedisSerializer<JSON>(JSON.class);
        // 配置序列化
        RedisCacheConfiguration config = RedisCacheConfiguration.defaultCacheConfig();
        config.serializeKeysWith(RedisSerializationContext.SerializationPair.fromSerializer(redisSerializer));
        config.serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(serializer));
        // 设置缓存的默认过期时间
        config.entryTtl(Duration.ofSeconds(exps));
        // 不缓存空值
        config.disableCachingNullValues();
        RedisCacheManager cacheManager = RedisCacheManager.builder(redisConnectionFactory).cacheDefaults(config).build();
        return cacheManager;
    }
}

缓存使用示例

分别对@Cacheable、@CachePut和@CacheEvict进行了举例。

@Cacheable(value = "users",key = "#collection.concat(#user.id)")
public void create(String collection, JSONObject  user)  {
  //do something
}

@CacheEvict(value = "users",key = "#collection.concat(#id)")
public void delete(String collection, String id)  {
  //do something
}

@Cacheable(value = "users",key = "#collection.concat(#id)")
public JSONObject getOne(String collection, String id)  {
  //do something
}

注意事项

• 要缓存的 Java 对象必须实现 Serializable 接口
• 在CacheManager对象中 设置缓存过期时间，否则缓存对象将永不过期
• 缓存key必须为string类型的值，否则需要进行类型转换