我发现至少有三种方法:

在您尝试序列化的实体上添加公共getter; 如果不需要公共getter，则在实体的顶部添加注释。这将改变Jackson的默认值，从visibility = default到@JsonAutoDetect(fieldVisibility = JsonAutoDetect.Visibility.ANY)，其中任何访问修饰符都是接受的; 通过设置objectMapperInstance.setVisibility(JsonMethod. setvisibility)全局更改您的ObjectMapper。字段,Visibility.ANY);。如果您不需要全局使用此功能，则应该避免这种情况。

根据您的需要进行选择。

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。

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。

我在通过hibernate代理对象进行延迟加载时遇到了类似的问题。通过注释具有惰性加载私有属性的类来解决这个问题:

@JsonIgnoreProperties({"hibernateLazyInitializer", "handler"})

我只有getter，在添加setter之后，问题就解决了。

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 ;   } 
}