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Redis – Spring Boot use component in a custom class?

I have a redis util :

@Component
public class RedisUtil {


    @Autowired
    private StringRedisTemplate stringRedisTemplate;


    public StringRedisTemplate getStringRedisTemplate() {
        return this.stringRedisTemplate;
    }
}

I want to use it in my custom class which I don’t want to be a component .

public class UserFeature {
    
    public String result;

    public String someMethod(){
        var redisUtil = new RedisUtil();
        var stringRedisTemplate = redisUtil.getStringRedisTemplate();
        ...
        this.result = query_result_from_stringRedisTemplate;
    }
}

When I use it like above , it raises a bean error .
What should I do ?

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3

Answers


  1. 0

    If you have a good reason for creating objects which shouldn’t be spring-managed, but still need to use spring beans, you can create a factory component which does the injection of spring beans into your non-spring object.

    @Component
class UserFeatureFactory {
private final RedisUtil redisUtil;
  @Autowired
  public UserFeatureFactory(RedisUtil redisUtil) { ... }

  public UserFeature createUserFeature() {
    return new UserFeature(redisUtil);
  }
}

// no spring annotations
class UserFeature {
  ...
  public UserFeature(RedisUtil redisUtil) {
    this.redisUtil = redisUtil
  }
  ...
}

    One nice feature of this approach is that it makes UserFeature easy to test — you can just pass its constructor a mock RedisUtil.

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  2. 0

    If for some reason you can’t turn UserFeature into a component, a general approach is to have a helper @Component class that provides access to Spring beans from non-Spring POJOs.

    @Component
public class SpringBeansProvider implements ApplicationContextAware {
     
    private static ApplicationContext context;
     
    public static <T> T getBean(String name, Class<T> beanClass) {
        return context.getBean(name, beanClass);
    }
     
    @Override
    public void setApplicationContext(ApplicationContext context) throws BeansException {
        SpringBeansProvider.context = context;
    }
}

    Then you can ask the Spring container for the RedisUtil bean instance as:

    public class UserFeature {
    // ...
    public String someMethod() {
        RedisUtil redisUtil = SpringBeansProvider.getBean("redisUtil", RedisUtil.class);
        // ...
    }
}

    This approach also lets you easily restrict which Spring beans can be accessed by non-Spring managed classes by having bean-specific getters in place of getBean().

    public static RedisUtil getRedisUtil() {
    return context.getBean("redisUtil", RedisUtil.class);
}

public String someMethod() {
    RedisUtil redisUtil = SpringBeansProvider.getRedisUtil();
    // ...
}
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  3. 0

    As of Spring 4.3, classes don’t need to have any Spring annotations whatsoever to be eligible for injection. Simply include a single constructor. (Lombok @RequiredArgsConstructor can do this for you, and it’s built into Groovy and Kotlin.)

    public class MyNotComponent {
  private final MyComponent component;

  public MyNotComponent(MyComponent component) {
    this.component = component;
  }
}
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