Redis系列一 - springboot 集成 redis Demo和原理

Myth丶恋晨 2021-06-24 15:56 354阅读 0赞

## 1. 概述 ##

本文介绍如何通过springboot集成redis并简单介绍其原理。

## 2. Demo和原理 ##

### 2.1. application.properties ###

application.properties配置参数如下

spring.redis.database=0
    spring.redis.host=192.168.188.7
    spring.redis.password=
    spring.redis.port=6379
    spring.redis.pool.max-idle=8
    spring.redis.pool.min-idle=0  
    spring.redis.pool.max-active=8  
    spring.redis.pool.max-wait=-1

**备注**： 如果你要使用集群redis，则可以配置以下参数spring.redis.sentinel.\* 或 spring.redis.cluster.\*

### 2.2. RedisProperties ###

以上参数会被自动封装到RedisProperties中： 此类被@ConfigurationProperties注解，表示从外部文件（如application.properties）注入属性值

@ConfigurationProperties(prefix = "spring.redis")
    public class RedisProperties { 
        /** * Database index used by the connection factory. */
        private int database = 0;
    
        /** * Redis url, which will overrule host, port and password if set. */
        private String url;
    
        /** * Redis server host. */
        private String host = "localhost";
    
        /** * Login password of the redis server. */
        private String password;
    
        /** * Redis server port. */
        private int port = 6379;
        // 其它参数略
    }

### 2.3. RedisAutoConfiguration ###

因为此类被@EnableConfigurationProperties注解，所以spring boot会触发对RedisProperties执行自动绑定属性值。

此类会自动创建bean对象: redis连接池JedisConnectionFactory和redis模板类(RedisTemplate和StringRedisTemplate)。我们会直接在应用中通过@Autowire注入以上对象

/** * EnableAutoConfiguration Auto-configuration for Spring Data's Redis support. * */
    @Configuration
    // 如果有以下三个类，则可以初始化此类
    @ConditionalOnClass({ JedisConnection.class, RedisOperations.class, Jedis.class })
    // @EnableConfigurationProperties：对RedisProperties执行自动绑定属性值
    @EnableConfigurationProperties(RedisProperties.class)
    public class RedisAutoConfiguration { 
    
        @Configuration
        // 如果有以下一个类，则可以初始化此类
        @ConditionalOnClass(GenericObjectPool.class)
        protected static class RedisConnectionConfiguration { 
    
            // 初始化JedisConnectionFactory工厂类对象，参数来自RedisProperties
            // 配置参数有：线程池，sentinel，cluster
            @Bean
            @ConditionalOnMissingBean(RedisConnectionFactory.class)
            public JedisConnectionFactory redisConnectionFactory()
                throws UnknownHostException {
                return applyProperties(createJedisConnectionFactory());
            }
    
    
        // 配置类 
        @Configuration
        protected static class RedisConfiguration { 
            // 初始化bean
            @Bean
            @ConditionalOnMissingBean(name = "redisTemplate")
            public RedisTemplate<Object, Object> redisTemplate(
                RedisConnectionFactory redisConnectionFactory)
                    throws UnknownHostException {
                RedisTemplate<Object, Object> template = new RedisTemplate<Object, Object>();
                template.setConnectionFactory(redisConnectionFactory);
                return template;
            }
    
            // 初始化bean
    @Bean       @ConditionalOnMissingBean(StringRedisTemplate.class)
            public StringRedisTemplate stringRedisTemplate(
                RedisConnectionFactory redisConnectionFactory)
                    throws UnknownHostException {
                StringRedisTemplate template = new StringRedisTemplate();
                template.setConnectionFactory(redisConnectionFactory);
                return template;
            }
    
        }

### 2.4. FirstExample ###

演示RedisTemplate的用法:

@Service
    public class FirstExample {
        @Autowired
        private RedisTemplate<String, String> template;
    
        public void save(String userId, String value) {
            template.boundListOps(userId).leftPush(value);
        }
    }

### 2.5. FirstApplication ###

springboot启动类

@SpringBootApplication
    public class FirstApplication { 
        private static final Logger log = LoggerFactory.getLogger(FirstApplication.class);
    
        public static void main(String[] args) {
            log.info("Start FirstApplication.. ");
            SpringApplication.run(FirstApplication.class, args);
        }
    }

查看源码@SpringBootApplication被@EnableAutoConfiguration注解

@Target(ElementType.TYPE)
    @Retention(RetentionPolicy.RUNTIME)
    @Documented
    @Inherited
    @SpringBootConfiguration
    @EnableAutoConfiguration
    @ComponentScan(excludeFilters = {
            @Filter(type = FilterType.CUSTOM, classes = TypeExcludeFilter.class),
            @Filter(type = FilterType.CUSTOM, classes = AutoConfigurationExcludeFilter.class) })
    public @interface SpringBootApplication {
    ....
    }

被@EnableAutoConfiguration注解时，springboot启动时会扫描对应jar包中的META-INF/spring-autoconfigure-metadata.properties文件，并初始化里面的配置的类。查看spring-autoconfigure-metadata.properties，里面配置了上文的RedisAutoConfiguration类，所以我们可以直接在类中注入RedisTemplate.

...
    org.springframework.boot.autoconfigure.data.redis.RedisAutoConfiguration=
    ...

### 2.6. FirstApplicationTests ###

测试类，执行类会在redis中创建一个值

@RunWith(SpringRunner.class)
    @SpringBootTest(classes=FirstApplication.class)
    public class FirstApplicationTests { 
        @Autowired
        private FirstExample firstExample;
    
        @Test
        public void save(){
            firstExample.save("name", "value");
        }
    }

## 3. 代码 \#\# ##

上文的代码详细见[这里][Link 1]

[Link 1]: https://github.com/hryou0922/spring_boot/tree/master/redis/src/main/java/com/hry/spring/redis/simple