11. 集成 Redis

11.1 说明

• SpringBoot 操作数据：sping-data、jpa、jdbc、mongodb、redis

• SpringBoot 2.× 后，jedis 被替换为 lettuce

  jedis：采用直连，多线程操作不安全，增强安全性需使用 jedis pool 连接池！更像 BIO 模式。

  lettuce：采用 netty，实例可在多个线程中共享，不存在线程不安全的情况！更像 NIO 模式。

11.2 源码分析

@Bean
@ConditionalOnMissingBean(name = "redisTemplate")
@ConditionalOnSingleCandidate(RedisConnectionFactory.class)
public RedisTemplate<Object, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
   // 默认的 RedisTemplate 没有过多的设置，redis 对象都需要序列化
   // 两个泛型都是 Object，需要强制转换为 <String, Object>
   RedisTemplate<Object, Object> template = new RedisTemplate<>();
   template.setConnectionFactory(redisConnectionFactory);
   return template;
}

@Bean
@ConditionalOnMissingBean
@ConditionalOnSingleCandidate(RedisConnectionFactory.class)
// 由于 String 是常用类型所以单独提出一个 bean
public StringRedisTemplate stringRedisTemplate(RedisConnectionFactory redisConnectionFactory) {
   StringRedisTemplate template = new StringRedisTemplate();
   template.setConnectionFactory(redisConnectionFactory);
   return template;
}

11.3 测试

(1) 导入依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>

(2) 配置 redis

# application.properties
spring.redis.host=127.0.0.1
spring.redis.port=6379

(3) 测试

● 传输字符串

@SpringBootTest
class RedisApplicationTests {

    @Autowired
    private RedisTemplate redisTemplate;

    @Test
    void contextLoads() {

        /**
         * redisTemplate 可操作不同的数据类型，可完成基本的操作，如 CRUD
         * opsForValue 字符串
         * opsForList
         * opsForSet
         * opsForHash
         * opsForZSet
         * opsForGeo
         * opsForHyperLogLog
         *
         * 获取 redis 连接对象
         * RedisConnection connection = redisTemplate.getConnectionFactory().getConnection();
         * connection.flushDb();
         * connection.flushAll() ;
         */

        redisTemplate.opsForValue().set("myKey", "why");
        System.out.println("myKey: " + redisTemplate.opsForValue().get("myKey"));
    }
}

● 传输对象

// 实体类
@Component
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User {
    private String name;
    private String password;
}

@Test
void test() throws JsonProcessingException {
    User user = new User("why", "123");
    redisTemplate.opsForValue().set("user", user);
    System.out.println(redisTemplate.opsForValue().get("user"));
}

● 传输 JSON

@Test
void test() throws JsonProcessingException {
    User user = new User("why", "123");
    // 将 Object 转换为 Json
    String jsonUser = new ObjectMapper().writeValueAsString(user);
    redisTemplate.opsForValue().set("user", jsonUser);
    System.out.println(redisTemplate.opsForValue().get("user"));
}

● 传输序列化对象

// 序列化的实体类
@Component
@Data
@AllArgsConstructor
@NoArgsConstructor
public class User implements Serializable {
    private String name;
    private String password;
}

@Test
void test() throws JsonProcessingException {
    User user = new User("why", "123");
    redisTemplate.opsForValue().set("user", user);
    System.out.println(redisTemplate.opsForValue().get("user"));
}

● Redis 用户端乱码问题

(4) 自定义配置类

@Configuration
public class RedisConfig {

    // 自定义 redisTemplate, 修改 RedisAutoConfiguration 中的 Bean
    @Bean
    @SuppressWarnings("all")
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory factory) {
        // <String, Object> 类型便于开发
        RedisTemplate<String, Object> template = new RedisTemplate<>();
        template.setConnectionFactory(factory);
        // Json 序列化配置
        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);
        // String 序列化配置
        StringRedisSerializer stringRedisSerializer = new StringRedisSerializer();
        // key 采用 string 的序列化方式
        template.setKeySerializer(stringRedisSerializer);
        // hash 的 key 采用 string 的序列化方式
        template.setHashKeySerializer(stringRedisSerializer);
        // value 采用 jackson 的序列化方式
        template.setValueSerializer(jackson2JsonRedisSerializer);
        // hash 的 value 采用 jackson 的序列化方式
        template.setHashValueSerializer(jackson2JsonRedisSerializer);
        template.afterPropertiesSet();
        return template;
    }
}

@Test
void test() throws JsonProcessingException {
    User user = new User("why", "123");
    redisTemplate.opsForValue().set("user", user);
    System.out.println(redisTemplate.opsForValue().get("user"));
}