忽略字段而不使用 Jackson 修改 POJO 类

Question

My POJO class has @JsonIgnore on the declaration of a field, not on the getter and setter methods. It is a generated file and I can't change much in it.

How do I ignore that field while writing using JsonGenerator.Setting ? Using @JsonIgnore on getters and setters works. But can't modify the generated POJO class.

Answer 1

Configuring Jackson to use only field annotations

Once the annotations are placed on the fields, you can configure ObjectMapper to use only the fields annotations, ignoring the annotations of getters and setters methods:

ObjectMapper mapper = new ObjectMapper();    
mapper.setVisibility(PropertyAccessor.ALL, Visibility.NONE);
mapper.setVisibility(PropertyAccessor.FIELD, Visibility.ANY);

Jackson mix-in annotations

It's a great alternative when modifying your POJOs is not an option. You can think of it as a kind of aspect-oriented way of adding more annotations during runtime, to augment statically defined ones.

Define a mix-in annotation interface (class would do as well):

public interface FooMixIn {

    @JsonIgnore
    String getBar();
}

Then configure ObjectMapper to use the defined interface (or class) as a mix-in for your POJO:

ObjectMapper mapper = new ObjectMapper().enable(SerializationFeature.INDENT_OUTPUT)
                                        .addMixIn(Foo.class, FooMixIn.class); 

Here are some usage considerations:

• All annotation sets that Jackson recognizes can be mixed in.
• All kinds of annotations (member method, static method, field, constructor annotations) can be mixed in.
• Only method (and field) name and signature are used for matching annotations: access definitions ( private , protected , ...) and method implementations are ignored.

For more details, check this page .

Answer 2

将这些字段定义为transients并避免它们被序列化，无论您使用什么 json 注释...