如何使用注释在改进2中解析android中的动态json

我有一个JSON结构，我想使用改进2（@Expose）解析。 下面我提到了JSON。 需要帮助来使用动态注释来解析它。

{ "status": 1, "message": "success", "data" : [ { "type": 1, "heading": "", "description": "", "created_on": 141123213, "author_id": 123, "author_name": "some name", "author_pic": "some_pic", "read_time": "3.1 min", "post_pic_url": "", "post_web_url": "", "isLiked": false, "isSaved": false, "totalLikes": 12 }, { "type": 2, "author_id": 123, "author_name": "some name", "author_pic": "some pic", "author_about": "", "tags":[ "travel", "weekends" ], "isFollowing": false }, { "type": 3, "poll_name": "Some name", "poll_options": [ "opt1", "opt2", "opt3" ], "author_id": 123, "author_name": "some name", "author_pic": "some pic", "isLiked": true, "isFollowing": false }, { "type": 4, "ad_url": "url", "ad_pic": "pic" }, { "type": 5, "tags": [ "tag1", "tag2", "tag3" ] } ] } 

我已经用所有5种类型更新了JSON结构。

Answer 1

1使用Retrofit转换示例GSON转换

2在gradle文件中添加com.squareup.retrofit2：converter-gson 3在Retrofit对象中添加转换器工厂

Retrofit retrofit = new Retrofit.Builder（）。baseUrl（Ws_Url）.addConverterFactory（GsonConverterFactory.create（））。client（clientBuilder.build（））。build（）;

4为您的响应创建Model类使用以下链接生成模型类http://www.jsonschema2pojo.org/

Answer 2

Retrofit不进行序列化和反序列化，但Gson确实如此。 您可能希望使用Google Gson extras包中的RuntimeTypeAdapterFactory 。 它不是在工件存储库中发布的，您只需将代码复制到项目中即可。 如果类型适配器有点复杂（因为它们与JSON流一起使用），您可能会发现JsonDeserializer更容易使用并且可能维护（它们使用JSON树消耗更多内存，但它是唯一的方式来到这里）。

定义类似于以下内容的映射：

 // There might be no the common root, and target lists might be parameterized with Object, but it's up to you abstract class Element { final int type = Integer.valueOf(0); // Since the number of types is really finite, we can define all known types in one place private Element() { } static final class Type1Element extends Element { // the rest of properties go here // Gson does not need constructors, neither we do (at least public ones) private Type1Element() { } } static final class Type2Element extends Element { // the rest of properties go here private Type2Element() { } } } 

 final class Response { final int status = Integer.valueOf(0); final String message = null; final T data = null; } 

现在解串器本身：

 final class ElementJsonDeserializer implements JsonDeserializer { private static final JsonDeserializer elementJsonDeserializer = new ElementJsonDeserializer(); private ElementJsonDeserializer() { } // The deserializer is essentially a singleton, but we hide away this fact making sure that only 1 instance exists static JsonDeserializer getElementJsonDeserializer() { return elementJsonDeserializer; } @Override public Element deserialize(final JsonElement jsonElement, final Type type, final JsonDeserializationContext context) throws JsonParseException { final int typeCode = jsonElement.getAsJsonObject().getAsJsonPrimitive("type").getAsInt(); // Simple dispatching here // RuntimeTypeAdapterFactory basically does the same switch ( typeCode ) { case 1: return context.deserialize(jsonElement, Type1Element.class); case 2: return context.deserialize(jsonElement, Type2Element.class); default: throw new JsonParseException("Unrecognized type: " + typeCode); } } } 

现在让它们一起工作（ response.json是你的JSON文档资源）：

 private static final Type type = new TypeToken>>() { }.getType(); private static final Gson gson = new GsonBuilder() .registerTypeAdapter(Element.class, getElementJsonDeserializer()) .create(); public static void main(final String... args) throws IOException { try ( final JsonReader jsonReader = getPackageResourceJsonReader(Q43802350.class, "response.json") ) { final Response> response = gson.fromJson(jsonReader, type); response.data .stream() .map(Element::getClass) .map(Class::getSimpleName) .forEach(System.out::println); } } 

输出：

Type1Element
Type2Element

当然，不要忘记在Retrofit构建器中使用GsonConverterFactory.create(gson)注册gson实例。