一、springboot中配置jackson有2中方式，yml中配置和配置类中配置。
以下示例主要以在全局配置返回对象进行序列号转json时忽略null和空字符为例：
（1）yml配置文件中配置，如下图所示：
（2）在配置类中配置
正常情况下，以上两种方式均可实现。但是有时候突然会出现配合失灵的情况，这是为什么呢，可能原因可能有2，加上了配置@EnableWebMvc 或配置类继承了WebMvcConfigurationSupport等关于webmvc的相关配置，这都会使得原有配置失效，看下官方关于这个的解释：
public class WebMvcConfigurationSupport extends Object implements ApplicationContextAware, ServletContextAware
This is the main class providing the configuration behind the MVC Java config. It is typically imported by adding @EnableWebMvc to an application@Configuration class. An alternative more advanced option is to extend directly from this class and override methods as necessary remembering to add@Configuration to the subclass and @Bean to overridden @Bean methods. For more details see the Javadoc of @EnableWebMvc.
This class registers the following HandlerMappings:
RequestMappingHandlerMapping ordered at 0 for mapping requests to annotated controller methods.
HandlerMapping ordered at 1 to map URL paths directly to view names.
BeanNameUrlHandlerMapping ordered at 2 to map URL paths to controller bean names.
HandlerMapping ordered at Integer.MAX_VALUE-1 to serve static resource requests.
HandlerMapping ordered at Integer.MAX_VALUE to forward requests to the default servlet.
Registers these HandlerAdapters:
RequestMappingHandlerAdapter for processing requests with annotated controller methods.
HttpRequestHandlerAdapter for processing requests with HttpRequestHandlers.
SimpleControllerHandlerAdapter for processing requests with interface-based Controllers.
Registers a HandlerExceptionResolverComposite with this chain of exception resolvers:
ExceptionHandlerExceptionResolver for handling exceptions through @ExceptionHandler methods.
ResponseStatusExceptionResolver for exceptions annotated with @ResponseStatus.
DefaultHandlerExceptionResolver for resolving known Spring exception types
Registers an AntPathMatcher and a UrlPathHelper to be used by:
the RequestMappingHandlerMapping,
the HandlerMapping for ViewControllers
and the HandlerMapping for serving resources
Note that those beans can be configured with a PathMatchConfigurer.
Both the RequestMappingHandlerAdapter and the ExceptionHandlerExceptionResolver are configured with default instances of the following by default:
a ContentNegotiationManager
a DefaultFormattingConversionService
a OptionalValidatorFactoryBean if a JSR-303 implementation is available on the classpath
a range of HttpMessageConverters depending on the third-party libraries available on the classpath.
出现如上问题的解决方法就是再次自定义messageConvert后问题即可解决，如下所示
增加jackson对LocalDate和LocalDateTime的序列化时，可增加如下配置
