无法在Spring Boot中将ProblemHandler设置为ObjectMapper

我尝试使用Jackson2ObjectMapperBuilderCustomizer将自定义问题处理程序添加到对象映射器：

@Bean public Jackson2ObjectMapperBuilderCustomizer customizer() { return new Jackson2ObjectMapperBuilderCustomizer() { @Override public void customize(Jackson2ObjectMapperBuilder builder) { ObjectMapper m = builder.build(); m.addHandler( new DeserializationProblemHandler() { @Override public boolean handleUnknownProperty(DeserializationContext ctxt, JsonParser p, JsonDeserializer deserializer, Object beanOrClass, String propertyName) throws IOException { System.out.println("ahahahaa"); return super.handleUnknownProperty(ctxt, p, deserializer, beanOrClass, propertyName); } } ); } }; } 

但是当我自动assemblyObjectMapper bean时，_problemHandlers属性为null。

我也试过用以下方法定制现有的ObjectMapper：

 @Autowired public customize(ObjectMapper mapper) { ... } 

但结果是一样的。 我不知道谁可以擦除这个属性。 我根本没有在另一个地方初始化对象映射器的另一个构建器/工厂/等。 我做错了什么？

Answer 1

通过Jackson2ObjectMapperBuilder或Jackson2ObjectMapperBuilderCustomizer直接将DeserializationProblemHandler添加到ObjectMapper是Jackson2ObjectMapperBuilderCustomizer 。 在build()器上调用build()是不行的，因为生成的ObjectMapper是方法的本地：Spring本身稍后将调用build() ，创建另一个ObjectMapper实例。

但是，可以通过注册Jackson模块来实现：

• 构建器有一个modules()方法
• 模块可以通过setupModule()访问SetupContext实例，该实例具有addDeserializationProblemHandler()方法

这应该工作

 @Bean public Jackson2ObjectMapperBuilderCustomizer customizer() { return new Jackson2ObjectMapperBuilderCustomizer() { @Override public void customize(Jackson2ObjectMapperBuilder builder) { builder.modules(new MyModule()); } }; } private static class MyModule extends SimpleModule { @Override public void setupModule(SetupContext context) { // Required, as documented in the Javadoc of SimpleModule super.setupModule(context); context.addDeserializationProblemHandler(new MyDeserializationProblemHandler()); } } private static class MyDeserializationProblemHandler extends DeserializationProblemHandler { @Override public boolean handleUnknownProperty(DeserializationContext ctxt, JsonParser p, JsonDeserializer deserializer, Object beanOrClass, String propertyName) throws IOException { System.out.println("ahahahaa"); return super.handleUnknownProperty(ctxt, p, deserializer, beanOrClass, propertyName); } }