Jackson ObjectMapper使用自定义序列化器和反序列化器

Question

我有一个配置Jackson ObjectMapper的类.它为我的对象类型添加了一些自定义序列化器和反序列化器,如下所示:

public class JsonMapperFactory {
    public static ObjectMapper createObjectMapper() {
        final SimpleModule module = new SimpleModule("customerSerializationModule", new Version(1, 0, 0, "static version"));
        addCustomDeserializersTo(module);
        addCustomSerializersTo(module);

        final ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.registerModule(module);
        return objectMapper;
    }
    private static void addCustomSerializersTo(final SimpleModule module) {
        module.addSerializer(DateTime.class, new DateTimeSerializer());
    }
    private static void addCustomDeserializersTo(final SimpleModule objectMapper) {
        objectMapper.addDeserializer(DateTime.class, new DateTimeDeserializer());
    }
}

我已经在他们自己的测试类中测试了我的客户序列化器,所以在我对这个JsonMapperFactory类的测试中,我试图简单地检查创建的ObjectMapper是否具有预期的序列化器(或反序列化器)这可以通过内省ObjectMapper来实现,但是它似乎没有任何机制来做到这一点.

有谁知道测试它的好方法？

对于反序列化器,我有以下内容:

private void assertThatObjectMapperUsesCorrectDeserializer(final Class<?> typeClazz, final Class<?> deserializerClazz) throws JsonMappingException {
    final  DeserializationConfig deserializationConfig = this.objectMapper.getDeserializationConfig();
    final JsonDeserializer<Object> deserializer = this.objectMapper.getDeserializerProvider().findTypedValueDeserializer(deserializationConfig, javaTypeFor(typeClazz), null);
    assertThat(deserializer, is(instanceOf(deserializerClazz)));
}
private JavaType javaTypeFor(final Class<?> clazz) {
    return TypeFactory.type(clazz); //deprecated method :(
}

这是非常详细的,并使用弃用的方法.

我还没有找到一种方法来对序列化器进行类似的测试.所以我目前使用序列化对象并检查它是否正确序列化(基本上复制了序列化程序测试)

任何想法都非常受欢迎.

Answer 1

从这里提供的答案和评论中,我最近重新设计了类,以便使用构建器Module和ObjectMapper.这允许我提供模拟并检查是否将正确的(de)序列化程序添加到模块中,然后按预期将模块注册到对象映射器.

对象映射器构建器:

public class ObjectMapperBuilder {
    ObjectMapper mapper;

    public ObjectMapperBuilder configure(final ObjectMapper mapper) {
        this.mapper = mapper;
        return this;
    }

    public ObjectMapperBuilder withModule(final Module module) {
        this.mapper.registerModule(module);
        return this;
    }

    public ObjectMapper build() {
        return this.mapper;
    }
}

模块构建器:

public class SimpleModuleBuilder {
    SimpleModule module;

    public SimpleModuleBuilder configure(final SimpleModule module) {
        this.module = module;
        return this;
    }

    public <X> SimpleModuleBuilder withSerializer(final Class<X> clazz, final JsonSerializer<X> serializer) {
        this.module.addSerializer(clazz, serializer);
        return this;
    }

    public <X> SimpleModuleBuilder withDeserializer(final Class<X> clazz, final JsonDeserializer<X> deserializer) {
        this.module.addDeserializer(clazz, deserializer);
        return this;
    }

    public SimpleModule build() {
        return this.module;
    }
}

最后,新的JsonMapperFactory:

public class JsonMapperFactory {

    public static ObjectMapper configureObjectMapper(final ObjectMapper mapper, final SimpleModule module) {
        final SimpleModuleBuilder modulebuilder = new SimpleModuleBuilder();

        final SimpleModule configuredModule = modulebuilder.configure(module)
            .withSerializer(DateTime.class, new DateTimeSerializer())
            .withDeserializer(DateTime.class, new DateTimeDeserializer())
            .build();

        final ObjectMapperBuilder objectMapperBuilder = new ObjectMapperBuilder();
        return objectMapperBuilder.configure(mapper).withModule(configuredModule).build();
    }
}

工厂方法仍在Spring配置中使用,但配置现在实例化空白Module,ObjectMapper然后将它们提供给工厂方法,然后再配置它们.