@Override
public void serialize(
    final Object value,
    final JsonGenerator gen,
    final SerializerProvider serializers
) throws IOException {
    if (value == null) {
        gen.writeString("");
        return;
    }

    // See if we have a serializer that is NOT the unknown serializer
    final JsonSerializer serializer = serializers.findValueSerializer(value.getClass());
    if (serializer != null && !(serializer instanceof UnknownSerializer)) {
        serializer.serialize(value, gen, serializers);
        return;
    }
    gen.writeString(value.toString());
}
 

@Test  // SPR-13375
@SuppressWarnings("rawtypes")
public void springHandlerInstantiator() {
	TestStandaloneMockMvcBuilder builder = new TestStandaloneMockMvcBuilder(new PersonController());
	builder.build();
	SpringHandlerInstantiator instantiator = new SpringHandlerInstantiator(builder.wac.getAutowireCapableBeanFactory());
	JsonSerializer serializer = instantiator.serializerInstance(null, null, UnknownSerializer.class);
	assertNotNull(serializer);
}
 

@Test  // SPR-13375
@SuppressWarnings("rawtypes")
public void springHandlerInstantiator() {
	TestStandaloneMockMvcBuilder builder = new TestStandaloneMockMvcBuilder(new PersonController());
	builder.build();
	SpringHandlerInstantiator instantiator = new SpringHandlerInstantiator(builder.wac.getAutowireCapableBeanFactory());
	JsonSerializer serializer = instantiator.serializerInstance(null, null, UnknownSerializer.class);
	assertNotNull(serializer);
}
 

/**
 * Helper method called to see if given serializer is considered to be
 * something returned by {@link #getUnknownTypeSerializer}, that is, something
 * for which no regular serializer was found or constructed.
 * 
 * @since 2.5
 */
public boolean isUnknownTypeSerializer(JsonSerializer<?> ser) {
    if ((ser == _unknownTypeSerializer) || (ser == null)) {
        return true;
    }
    // 23-Apr-2015, tatu: "empty" serializer is trickier; needs to consider
    //    error handling
    if (isEnabled(SerializationFeature.FAIL_ON_EMPTY_BEANS)) {
        if (ser.getClass() == UnknownSerializer.class) {
            return true;
        }
    }
    return false;
}
 

@Test
@SuppressWarnings("rawtypes")
public void springHandlerInstantiator() {
	TestStandaloneMockMvcBuilder builder = new TestStandaloneMockMvcBuilder(new PersonController());
	builder.build();
	SpringHandlerInstantiator instantiator = new SpringHandlerInstantiator(builder.wac.getAutowireCapableBeanFactory());
	JsonSerializer serializer = instantiator.serializerInstance(null, null, UnknownSerializer.class);
	assertNotNull(serializer);
}
 

@Override
public JsonSerializer<?> modifySerializer(SerializationConfig config, BeanDescription beanDesc, JsonSerializer<?> serializer) {
  if (serializer instanceof UnknownSerializer || serializer instanceof BeanSerializer) {
    return customEncodersSerializer;
  } else {
    return serializer;
  }
}
 

/**
 * Method called to get the serializer to use if provider
 * cannot determine an actual type-specific serializer
 * to use; typically when none of {@link SerializerFactory}
 * instances are able to construct a serializer.
 *<p>
 * Typically, returned serializer will throw an exception,
 * although alternatively {@link com.fasterxml.jackson.databind.ser.std.ToStringSerializer}
 * could be returned as well.
 *
 * @param unknownType Type for which no serializer is found
 */
public JsonSerializer<Object> getUnknownTypeSerializer(Class<?> unknownType) {
    // 23-Apr-2015, tatu: Only return shared instance if nominal type is Object.class
    if (unknownType == Object.class) {
        return _unknownTypeSerializer;
    }
    // otherwise construct explicit instance with property handled type
    return new UnknownSerializer(unknownType);
}