SpringBoot2.0，我通过下面的代码来解决它:

@Bean public ObjectMapper objectMapper() {
 return new ObjectMapper().disable(SerializationFeature.FAIL_ON_EMPTY_BEANS);}

Jackson要序列化该类，SomeString字段需要是公共的(目前它是包级隔离)，或者需要为它定义getter和setter方法。

虽然我添加了getter和setter，但我得到了相同的错误。后来我发现了一个bug，这是由声纳的建议，我cgahnged的getter和setter作为保护，这是导致问题的原因。一旦我修复了，它就会像预期的那样工作。

Jackson使用getter和setter序列化。/反序列化。 所以在模型类中添加getter和setter。

As already described, the default configuration of an ObjectMapper instance is to only access properties that are public fields or have public getters/setters. An alternative to changing the class definition to make a field public or to provide a public getter/setter is to specify (to the underlying VisibilityChecker) a different property visibility rule. Jackson 1.9 provides the ObjectMapper.setVisibility() convenience method for doing so. For the example in the original question, I'd likely configure this as

myObjectMapper.setVisibility(JsonMethod.FIELD, Visibility.ANY);

杰克逊>2.0:

myObjectMapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);

有关相关配置选项的更多信息和详细信息，我建议查看ObjectMapper.setVisibility()上的JavaDocs。

添加setter和getter也将解决这个问题，因为它为我固定。 为例:

public class TestA {
    String SomeString = "asd";

    public String getSomeString () {        return SomeString ;     }

    public void setSomeString (String SS ) {        SomeString = SS ;   } 
}