Question

给出以下JSON：

{
    "authors": [{
        "name": "Stephen King",
        "books": [{
            "title": "Carrie"
        }, {
            "title": "The Shining"
        }, {
            "title": "Christine"
        }, {
            "title": "Pet Sematary"
        }]
    }]
}

这个对象结构：

public class Author {
    private List<Book> books;
    private String name;
}

public class Book {
    private transient Author author;
    private String title;
}

是否有办法使用Google Java库Gson反序列化JSON，并且books对象引用了＃34; parent＆＃34;作者对象？

是否可以不使用使用自定义反序列化程序？

如果是：怎么样？
如果否：是否仍然可以使用自定义反序列化程序执行此操作？

Answer 1

在这种情况下，我会为父对象实现自定义JsonDeserializer，并传播Author信息，如下所示：

public class AuthorDeserializer implements JsonDeserializer<Author> {
    @Override
    public Author deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {
        final JsonObject authorObject = json.getAsJsonObject();

        Author author = new Author();
        author.name = authorObject.get("name").getAsString();

        Type booksListType = new TypeToken<List<Book>>(){}.getType();
        author.books = context.deserialize(authorObject.get("books"), booksListType);

        for(Book book : author.books) {
            book.author = author;
        }

        return author;
    }   
}

请注意，我的示例省略了错误检查。你可以像这样使用它：

Gson gson = new GsonBuilder()
    .registerTypeAdapter(Author.class, new AuthorDeserializer())
    .create();

为了展示它的工作原理，我只选择了＃34;作者＆＃34;来自您的示例JSON的密钥，允许我这样做：

JsonElement authorsJson  = new JsonParser().parse(json).getAsJsonObject().get("authors");

Type authorList = new TypeToken<List<Author>>(){}.getType();
List<Author> authors = gson.fromJson(authorsJson, authorList);
for(Author a : authors) {
    System.out.println(a.name);
    for(Book b : a.books) {
        System.out.println("\t " + b.title + " by " + b.author.name);
    }
}

打印出来：

Stephen King
     Carrie by Stephen King
     The Shining by Stephen King
     Christine by Stephen King
     Pet Sematary by Stephen King

使用Gson反序列化JSON时引用父对象

1 个答案: