如何在 Restlet 中注册 Jackson Jdk8 模块

Question

有没有可能注册jackson-datatype-jdk8扩展包中的jackson-datatype-jdk8模块？我需要利用新的可选特性。我的猜测是，它应该可以通过转换器服务（getConverterService（））访问，但我在留档中找不到任何提示如何设置模块的内容。

Answer 1

@tarka的良好开端，但给了我流错误;我提出了一些[较低影响]的改进：

public class CustomJacksonConverter extends JacksonConverter {

    @Override
    protected <T> JacksonRepresentation<T> create(MediaType mediaType, T source) {
        return new CustomJacksonRepresentation<>(mediaType, source);
    }

    @Override
    protected <T> JacksonRepresentation<T> create(Representation source, Class<T> objectClass) {
        return new CustomJacksonRepresentation<>(source, objectClass);
    }

}

然后…

public class CustomJacksonRepresentation<T> extends JacksonRepresentation<T> {

    public CustomJacksonRepresentation(MediaType mediaType, T object) {
        super(mediaType, object);
    }

    public CustomJacksonRepresentation(Representation representation, Class<T> objectClass) {
        super(representation, objectClass);
    }

    public CustomJacksonRepresentation(T object) {
        super(object);
    }

    @Override
    protected ObjectMapper createObjectMapper() {
        ObjectMapper mapper = super.createObjectMapper();
        mapper.registerModule(new Jdk8Module());
        return mapper;
    }

}

并以与@tarka相同的方式更换转换器

Answer 2

我最终从各种来源拼凑出了一个适用于Restlet 2.3的答案

第一步是创建自定义 Jackson 转换器，以实现您的任何自定义要求：

public class CustomJacksonConverter extends JacksonConverter { 
    @Override 
    protected <T> JacksonRepresentation<T> create(MediaType mediaType, T source) { 
        ObjectMapper mapper = createMapper(); 
        JacksonRepresentation<T> jr = new JacksonRepresentation<T>(mediaType, source); 
        jr.setObjectMapper(mapper); 
        return jr; 
    } 

    @Override 
    protected <T> JacksonRepresentation<T> create(Representation source, Class<T> objectClass) { 
        ObjectMapper mapper = createMapper(); 
        JacksonRepresentation<T> jr = new JacksonRepresentation<T>(source, objectClass); 
        jr.setObjectMapper(mapper); 
        return jr; 
    } 


    private ObjectMapper createMapper() { 
        JsonFactory jsonFactory = new JsonFactory(); 
        jsonFactory.configure(JsonGenerator.Feature.AUTO_CLOSE_TARGET, false); 
        ObjectMapper mapper = new ObjectMapper(jsonFactory); 
        mapper.registerModule(new Jdk8Module()); 
        return mapper; 
    } 

} 

然后，您需要创建一种方法，用新转换器的副本替换默认的Jackson转换器:

static void replaceConverter(
            Class<? extends ConverterHelper> converterClass,
            ConverterHelper newConverter) {

        ConverterHelper oldConverter = null;

        List<ConverterHelper> converters = Engine.getInstance().getRegisteredConverters();
        for (ConverterHelper converter : converters) {
            if (converter.getClass().equals(converterClass)) {
                converters.remove(converter);
                oldConverter = converter;
                break;
            }
        }

        converters.add(newConverter);
    }

您现在可以替换入站根中的转换器：

replaceConverter(JacksonConverter.class, new CustomJacksonConverter());