GSON反序列化JSON具有不同的值类型 [英] Gson deserialize json with varying value types

问题描述

我想反序列化 JSONArray 与GSON，一个值类型可以改变，值in_wanted可以是一个布尔或的JSONObject 。

I'm trying to deserialize a JSONArray with Gson, one the values' type can vary, the value "in_wanted" can be either a boolean or a JSONObject.

in_wanted为布尔：

in_wanted as boolean:

{
"movies": [
        {
            "title": "example boolean",
            "in_wanted": false
        }
    ]           
}

in_wanted为的JSONObject ：

{
"movies": [
        {
            "title": "example object",
            "in_wanted": {
                "profile": {
                    "value": false
                }
            }
        }
    ]           
}

我需要时，它是可用的对象，我需要一个解串器返回空值时的in_wanted的值是一个布尔值。什么是与GSON做到这一点的最好方法是什么？

I need the object whenever it's available and i need a deserializer to return null whenever the value of "in_wanted" is a boolean. What would be the best way to do this with Gson?

推荐答案

您可以使用自定义解串器做到这一点。比赛一开始，我们应该创建数据模型，可以重新present你的JSON。

You can do this with custom deserializer. At the start we should create data model which can represent your JSON.

class JsonEntity {

    private List<Movie> movies;

    public List<Movie> getMovies() {
        return movies;
    }

    public void setMovies(List<Movie> movies) {
        this.movies = movies;
    }

    @Override
    public String toString() {
        return "JsonEntity [movies=" + movies + "]";
    }
}

class Movie {

    private String title;
    private Profile in_wanted;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public Profile getIn_wanted() {
        return in_wanted;
    }

    public void setIn_wanted(Profile in_wanted) {
        this.in_wanted = in_wanted;
    }

    @Override
    public String toString() {
        return "Movie [title=" + title + ", in_wanted=" + in_wanted + "]";
    }
}

class Profile {

    private boolean value;

    public boolean isValue() {
        return value;
    }

    public void setValue(boolean value) {
        this.value = value;
    }

    @Override
    public String toString() {
        return String.valueOf(value);
    }
}

现在，当我们拥有所有需要的类，我们应该实施新的定制解串器：

Now when we have all needed classes we should implement new custom deserializer:

class ProfileJsonDeserializer implements JsonDeserializer<Profile> {
    @Override
    public Profile deserialize(JsonElement jsonElement, Type type,
            JsonDeserializationContext context) throws JsonParseException {
        if (jsonElement.isJsonPrimitive()) {
            return null;
        }

        return context.deserialize(jsonElement, JsonProfile.class);
    }
}

class JsonProfile extends Profile {

}

请对 JsonProfile 类看看。我们必须创建它，以避免反序列化循环（棘手的问题）。

Please have a look on JsonProfile class. We have to create it to avoid "deserialization loop" (tricky part).

现在我们可以测试我们使用的测试方法解决方案：

And now we can test our solution with test method:

GsonBuilder builder = new GsonBuilder();
builder.registerTypeAdapter(Profile.class, new ProfileJsonDeserializer());
Gson gson = builder.create();

JsonEntity jsonEntity = gson.fromJson(new FileReader("/tmp/json.txt"),
        JsonEntity.class);
System.out.println(jsonEntity);

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