import com.fasterxml.jackson.databind.ser.std.NullSerializer; //导入依赖的package包/类
private SchemaAware getValueSerializer(Object valueAsJavaType) throws JsonMappingException {

        SerializerProvider serializerProvider = new DefaultSerializerProvider.Impl().createInstance(OBJECT_MAPPER.getSerializationConfig(), BeanSerializerFactory.instance);

        if (valueAsJavaType == null) {
            return NullSerializer.instance;
        } else {
            Class<? extends Object> javaTypeForValue = valueAsJavaType.getClass();
            JsonSerializer<Object> valueSerializer = serializerProvider.findValueSerializer(javaTypeForValue, null);
            return (SchemaAware) valueSerializer;
        }
    }
 

import com.fasterxml.jackson.databind.ser.std.NullSerializer; //导入依赖的package包/类
public CustomObjectMapper() {
	DefaultSerializerProvider sp = new DefaultSerializerProvider.Impl();
	sp.setNullValueSerializer(NullSerializer.instance);
	this.setSerializerProvider(sp);
}
 

import com.fasterxml.jackson.databind.ser.std.NullSerializer; //导入依赖的package包/类
public final JsonSerializer<?> getNullSerializer()
{
  return NullSerializer.instance;
}