Question

使用多个配置的ObjectMappers是否可以使用Jackson设置Jersey进行序列化/反序列化？

我希望能够做的是注册“默认”杰克逊ObjectMapper然后能够注册另一个功能，该功能提供ObjectMapper一些特殊配置，在某些情况下会“覆盖”“默认”ObjectMapper。

例如，此ContextResolver将用于“默认”映射器：

@Provider
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public class JacksonMapperProvider implements ContextResolver<ObjectMapper> {
    private final ObjectMapper mObjectMapper;

    public JacksonMapperProvider() {
        mObjectMapper = createMapper();
    }

    protected abstract ObjectMapper createMapper() {
        ObjectMapper mapper = createMapper();

        return mapper
            .setSerializationInclusion(Include.ALWAYS)
            .configure(JsonParser.Feature.ALLOW_COMMENTS, true)
            .configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true)
            .configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true)
            .configure(JsonParser.Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true);
    }

    @Override
    public ObjectMapper getContext(Class<?> type) {
        return mObjectMapper;
    }
}

此ContextResolver将覆盖“默认”映射器：

@Provider
@Consumes(MediaType.APPLICATION_JSON)
@Produces(MediaType.APPLICATION_JSON)
public class SpecializedMapperProvider implements ContextResolver<ObjectMapper> {
    private final ObjectMapper mObjectMapper;

    public SpecializedMapperProvider() {
        mObjectMapper = createMapper();
    }

    protected abstract ObjectMapper createMapper() {
        ObjectMapper mapper = createMapper();

        return mapper
            .disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
            .setDateFormat(new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS"))
            .registerModule(new SpecializedModule1())
            .registerModule(new SpecializedModule2());
    }

    @Override
    public ObjectMapper getContext(Class<?> type) {
        if(SomeType.isAssignableFrom(type)) {
            return mObjectMapper;
        }
        return null;
    }
}

我在JacksonJsonProvider代码中看到杰克逊支持ObjectMapper提供商注入/解析。然而，在实践中，我所看到的是提供者的“顺序”似乎是随机的（我猜它不是，但我不能理清如何控制顺序）。有时“覆盖”出现在“默认”之前，一切正常，但在下次服务器启动时，订单会发生变化。

我试图通过多种方式实现这一目标，包括：

手动注册ContextResolver<ObjectMapper>实施（按不同顺序）
通过ContextResolver<ObjectMapper>注释

@Provider

注册时指定优先级

我使用以下内容：

Jersey 2.8
Jackson 2.3.3

也许我采取了一种完全错误的做法？有没有更好的方法来实现我想要做的事情？也许我应该只定义两个独立的JAX-RS应用程序，并为每个应用程序配置一个ObjectMapper配置？

Answer 1

您可以配置提供商的顺序，但在这种情况下最好使用一个提供商：

@Provider
public class JacksonMapperProvider implements ContextResolver<ObjectMapper> {
    private final ObjectMapper defaultMapper;
    private final ObjectMapper specializedMapper;

    public JacksonMapperProvider() {
        defaultMapper = createDefaultMapper();
        specializedMapper = createSpecializedMapper();
    }

    private static ObjectMapper createDefaultMapper() {
        return new ObjectMapper()
            .setSerializationInclusion(Include.ALWAYS)
            .configure(JsonParser.Feature.ALLOW_COMMENTS, true)
            .configure(JsonParser.Feature.ALLOW_UNQUOTED_FIELD_NAMES, true)
            .configure(JsonParser.Feature.ALLOW_SINGLE_QUOTES, true)
            .configure(JsonParser.Feature.ALLOW_UNQUOTED_CONTROL_CHARS, true);
    }

    private static ObjectMapper createSpecializedMapper() {
        return new ObjectMapper()
            .disable(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS)
            .setDateFormat(new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS"))
            .registerModule(new SpecializedModule1())
            .registerModule(new SpecializedModule2());
    }

    @Override
    public ObjectMapper getContext(Class<?> type) {
        if (SomeType.isAssignableFrom(type)) {
            return specializedMapper;
        }
        else {
            return defaultMapper;
        }
    }
}

Answer 2

在Jersey中使用Jackson配置多个ObjectMapper

2 个答案: