MappingJacksonJsonView:忽略不使用@JsonIgnore的字段

Question

我需要忽略POJO中的某些字段,因为它们是延迟加载的和/或在某些情况下创建无限递归(父对齐的一对多Childs,Child多对一父对象).我的POJO驻留在另一个不知道Jackson,JSON等的jar中.

如何在不使用注释的情况下有效地告诉Jackson忽略这些字段？通过配置将是最好的.

谢谢

Answer 1

您可以使用以下代码编写带有Java代码的Custom Serializer和De-Serializer:

class CustomSerializer extends JsonSerializer<ARow> {
@Override
public Class<ARow> handledType() {
    return ARow.class;
}

public void serialize(ARow value, JsonGenerator jgen, SerializerProvider provider)
        throws IOException, JsonProcessingException {
    jgen.writeStartObject();
    jgen.writeStringField("ounc", value.ounces.toLowerCase()); //Do this for all of your relevant properties..
    jgen.writeEndObject();
}

}

并向杰克逊注册此自定义序列化器:

ObjectMapper m = new ObjectMapper();
SimpleModule testModule = new SimpleModule("MyModule", new Version(1, 0, 0, null));
testModule.addSerializer(new CustomSerializer());
m.registerModule(testModule);

要使用Spring进行设置,MappingJacksonJsonView您需要扩展自己的ObjectMapper

public class MyCustomObjectMapper extends ObjectMapper {
    public MyCustomObjectMapper() {
        SimpleModule module = new SimpleModule("My Module", new Version(1, 0, 0, "SNAPSHOT"));
        module.addSerializer(new CustomSerializer());
        module.addSerializer(new CustomSerializer2());
        // etc
        this.registerModule(module);
    }
}

为它创建一个bean

<bean id="myCustomObjectMapper" class="com.foo.proj.objectmapper.MyCustomObjectMapper"/>

并将它注入你的 MappingJacksonJsonView

<bean class="org.springframework.web.servlet.view.json.MappingJacksonJsonView">
    <property name="objectMapper" ref="myCustomObjectMapper"/>
</bean>