import com.fasterxml.jackson.databind.ser.BeanSerializer; //导入依赖的package包/类
@Override
 protected void serializeFields(Object bean, final JsonGenerator gen, SerializerProvider provider) throws IOException {
     if (bean instanceof ExtendedJsonWrapper) {
         ExtendedJsonWrapper mixin = (ExtendedJsonWrapper) bean;
         Object origin = mixin.getOrigin();

         BeanSerializer serializer = (BeanSerializer) provider.findValueSerializer(origin.getClass());
         new ExtendedJsonSerializer(serializer).serializeFieldsFiltered(origin, gen, provider);
         
         Set<Entry<String, Object>> entries = mixin.getMixed().entrySet();
         
         //gen.writeObjectField("mixedIn", mixin.getMixed());
         
         for (Entry<String, Object> entry : entries) {
	if(entry.getValue() != null){
		 try {
  			        gen.writeObjectField(entry.getKey(), entry.getValue());
  			    } catch (IOException e) {
  			        throw new RuntimeException(e);
  			    }
	}
}

     } else {
         super.serializeFields(bean, gen, provider);
     }

 }
 

import com.fasterxml.jackson.databind.ser.BeanSerializer; //导入依赖的package包/类
private JsonSerializer<Object> findSerializer(Class<?> type, SerializerProvider provider, boolean eventBean)
	throws JsonMappingException
{
	JsonSerializer<Object> serializer = serializers.serializerFor(type);
	if (serializer != null)
		return serializer;
	serializer = provider.findValueSerializer(type, null);
	if (eventBean)
		serializer = new EventBeanSerializer((BeanSerializer)serializer);
	serializers = serializers.newWith(type, serializer);
	return serializer;
}
 

import com.fasterxml.jackson.databind.ser.BeanSerializer; //导入依赖的package包/类
@Override
public JsonSerializer<?> modifySerializer(SerializationConfig config, BeanDescription beanDesc,
		JsonSerializer<?> serializer) {
	if (serializer instanceof BeanSerializer) {
		return new BeanSerializerWrapper((BeanSerializer) serializer);
	} else {
		return serializer;
	}
}
 

import com.fasterxml.jackson.databind.ser.BeanSerializer; //导入依赖的package包/类
EventBeanSerializer(BeanSerializer src) {
	super(src);
}
 

import com.fasterxml.jackson.databind.ser.BeanSerializer; //导入依赖的package包/类
protected BeanSerializerWrapper(BeanSerializer src) {
	super(src);
	this.serializer = src;
}
 

import com.fasterxml.jackson.databind.ser.BeanSerializer; //导入依赖的package包/类
public ExtensibleObjectSerializer(BeanSerializer src) {
  super(src);
}
 

import com.fasterxml.jackson.databind.ser.BeanSerializer; //导入依赖的package包/类
@Override
public JsonSerializer<?> modifySerializer(SerializationConfig config, BeanDescription beanDesc, JsonSerializer<?> serializer) {
  return (serializer instanceof BeanSerializer) ? new ExtensibleObjectSerializer((BeanSerializer) serializer) : serializer;
}
 

import com.fasterxml.jackson.databind.ser.BeanSerializer; //导入依赖的package包/类
/**
 * Constructs and initializes a JsonService with an {@link ObjectService}.
 * 
 * @param objectService
 */
public DefaultJsonService(final ObjectService objectService) {

	idToObjDeserializer = new UntypedObjectDeserializer(null, null) {

		@Override
		public Object deserialize(JsonParser p, DeserializationContext ctxt)
			throws IOException, JsonProcessingException
		{
			final Object obj = super.deserialize(p, ctxt);
			if (!(obj instanceof String && ((String) obj).startsWith("object:")))
				return obj;
			final String id = (String) obj;
			if (!objectService.contains(id)) {
				throw new JsonMappingException(p, "Object does not exist");
			}
			final ObjectInfo info = objectService.find(id);
			info.updateLastUsed();
			return info.getObject();
		}
	};

	final JsonSerializer<Object> objToIdSerializer =
		new JsonSerializer<Object>()
	{

			@Override
			public void serialize(Object value, JsonGenerator gen,
				SerializerProvider serializers) throws IOException,
				JsonProcessingException
		{
				gen.writeString(objectService.register(value, "DefaultJsonService"));
			}

		};

	final SimpleModule objToIdModule = new SimpleModule();
	objToIdModule.setSerializerModifier(new BeanSerializerModifier() {

		@Override
		public JsonSerializer<?> modifySerializer(SerializationConfig config,
			BeanDescription beanDesc, JsonSerializer<?> serializer)
		{
			if (Mixins.support(beanDesc.getBeanClass())) return serializer;
			// If the serialized class is unknown (i.e. serialized using the general
			// BeanSerializer) or should not be serialized (i.e. complicated class
			// implemented interfaces such as Iterable), would be serialized as an
			// ID.
			if (serializer instanceof BeanSerializer) return objToIdSerializer;
			if (notSerialized(beanDesc.getBeanClass())) return objToIdSerializer;
			return serializer;

		}
	});
	objToIdMapper = new ObjectMapper();
	objToIdMapper.registerModule(objToIdModule);

	// register Jackson MixIns to obtain better json output format for some
	// specific types
	Mixins.registerMixIns(objToIdMapper);
}