com.fasterxml.jackson.databind.JsonSerializer按键排除字段

Question

I have a class which I do not have control over it's source:

public class SomeClassImpl implements SomeClass {
    private SomeField someFiled; // Not serializable
    ... // Some other fields that are serializable
}

So this class is not fully Serializable , and I am running into StackOverflowError when I try to serialize it as json using Spring Boot as @ResponseBody .

I have two controller methods:

@ResponseBody public SomeClassImpl get();

@ResponseBody public SomeOtherClass find();

I have control over the source of SomeOtherClass which includes SomeClass as a property.

I could not figure out how to ignore a field using @JsonIgnore annotation, I probably need to to control the source.What I can do with annotations is that I can ignore SomeClass property from SomeOtherClass which does not help the first method above. So I decided to implement JsonSerializer<SomeClassImpl> :

@Override
public void serialize(SomeClassImpl someClass, JsonGenerator jsonGenerator, SerializerProvider serializerProvider) throws IOException, JsonProcessingException {
    // I need to write all fields except some
}

Or can I handle this with annotations? If yes how? Thanks.

Answer 1

When modifying the source code is not an option, you can use mix-in annotations to add Jackson annotations to a bean.

First define a mix-in annotation interface or class:

public interface FooMixIn {

    @JsonIgnore
    Object getBiz();
}

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

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

---

• 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, have a look at the Jackson documentation .