springboot Unboxing of redisTemplate. may produce NullPointerException

Question

I use springboot(2.3.1) and Lettuce in project

Filter

@Slf4j
@WebFilter(filterName = "requestWrapperFilter", urlPatterns = {"/*"})
public class RequestWrapperFilter implements Filter {
    @Resource
    private RedisTemplate redisTemplate;
    
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    ...
                if (redisTemplate.hasKey(COMMON_HEAD_TOKEN_NAME + token)) {
                    redisTemplate.delete(COMMON_HEAD_TOKEN_NAME + token);
                }
    }
    ...
}

the RedisConfig configration like this:

@Configuration
@Component
public class RedisConfig {
    @Bean
    public RedisTemplate<String, Serializable> redisTemplate(LettuceConnectionFactory connectionFactory) {
        RedisTemplate<String, Serializable> redisTemplate = new RedisTemplate<>();
        redisTemplate.setKeySerializer(new StringRedisSerializer());
        redisTemplate.setValueSerializer(new Jackson2JsonRedisSerializer(Object.class));
        redisTemplate.setConnectionFactory(connectionFactory);
        return redisTemplate;
    }
}

but when I calling interface , the application shows the following error:

there is WARNING:

Unboxing of 'redisTemplate.hasKey(COMMON_HEAD_TOKEN_NAME + token)' may produce 'NullPointerException' 
Unchecked call to 'hasKey(K)' as a member of raw type 'org.springframework.data.redis.core.RedisTemplate' 

can I ignore ?

Answer 1

The first warning means that the hasKey method returns an object wrapper, but using it inside an if condition implicitly unboxes it (i.e. converts the result of the call to a primitive value). If for some reason the hasKey method returns null, you'll get an error. To be on the safe side, check the presence of the key as follows:

if (Boolean.TRUE.equals(redisTemplate.hasKey(COMMON_HEAD_TOKEN_NAME + token))) {

The second warning means that your redisTemplate field has a raw type, however, the RedisTemplate class is parameterized. To get rid of the warning, define the redisTemplate field in the filter as follows:

@Resource
private RedisTemplate<String, Serializable> redisTemplate;