具有改造和LiveData问题的Android MVVM

Question

嘿，我是mvvm架构的新手，我试图使用改造功能来调用Google图书api，并在列表视图中显示数据，并且我遇到了一些问题。

检查码：https://github.com/OmarQaisi/MVVM-Example

1-是否可以进行改进以返回对象列表而不是JsonObject（如果我的模型类不具有json主体内的所有变量）？一个简单的例子：可以说Json响应有4个实例（bookName，bookPages，bookAuthor，bookPrice），而我的Book.java类只有2个实例（bookName和bookAuthor）可以翻新自动将Json响应转换为Book Object吗？

到目前为止，这是我将JsonObject转换为我的应用程序中的Book对象的方式：

public class BookViewModel extends ViewModel {

private static final String TAG = "BookViewModel";
public MutableLiveData<List<Book>> books = new MutableLiveData<>();
private List<Book> dataSet = new ArrayList<>();

public void getBooks(String bookName, int maxResult){

    BookClient.getInstance().getBooks(bookName,maxResult).enqueue(new Callback<JsonObject>() {
        @Override
        public void onResponse(Call<JsonObject> call, Response<JsonObject> response) {
            if (!response.isSuccessful()) {
                Log.d(TAG, "Code: " + response.code());
                return;
            }
            try {
                JsonObject root = response.body();
                JsonArray booksArray = root.getAsJsonArray("items");
                for (int i=0; i<booksArray.size(); i++){
                    JsonObject currentObject = booksArray.get(i).getAsJsonObject();
                    JsonObject info = currentObject.getAsJsonObject("volumeInfo");
                    JsonElement bookTitle = info.get("title");
                    if(info.has("averageRating") && info.has("description")){
                        JsonElement bookDescription= info.get("description");
                        JsonElement bookRating = info.get("averageRating");
                        JsonElement bookURL = info.get("infoLink");
                        JsonElement bookRatingReviews = info.get("ratingsCount");
                        JsonElement bookPageCount = info.get("pageCount");
                        String bookCategories= "";
                        if(info.has("categories")){
                            JsonArray categories = info.getAsJsonArray("categories");
                            JsonElement bookCategoriesElement = categories.get(0);
                            bookCategories = bookCategoriesElement.getAsString();
                        }

                        JsonObject imageLinks = info.getAsJsonObject("imageLinks");
                        JsonElement bookThumbnail = imageLinks.get("thumbnail");
                        JsonElement bookPublishedDate = info.get("publishedDate");
                        JsonElement bookAuthor;
                        if(info.has("authors")){
                            JsonArray authors = info.getAsJsonArray("authors");
                            bookAuthor = authors.get(0);
                        }else
                            bookAuthor = info.get("publisher");

                        dataSet.add(new Book(bookTitle.getAsString(),
                                bookAuthor.getAsString(),
                                bookDescription.getAsString(),
                                bookThumbnail.getAsString(),
                                bookURL.getAsString(),
                                bookCategories,
                                bookPublishedDate.getAsString(),
                                bookRating.getAsDouble(),
                                bookRatingReviews.getAsInt(),
                                bookPageCount.getAsInt()));
                    }
                }
            }catch (JsonParseException e){
                Log.e(TAG, "Problem parsing the book JSON results", e);
            }
            books.setValue(dataSet);
        }

        @Override
        public void onFailure(Call<JsonObject> call, Throwable t) {
            Log.d(TAG, "onFailure: " + t.getMessage());
        }
    });

}//getBooks

} // BookViewModel

2-我搜索新书后，我的Listview没有更新！

3-使用mvvm进行改造时，应该避免任何错误吗？还是我在代码中制作了其中任何一个？请任何提示/建议都意味着很多。

谢谢您<3 <3

Answer 1

1。是否可以获取翻新的对象列表回答->是，点击api后，使用序列化将Json Element转换为Java对象。2。为什么您的列表未更新，因为您已将数据集声明为全局数据集，所以我对其进行了修复

public class BookViewModel extends ViewModel {

private static final String TAG = "BookViewModel";
public MutableLiveData<List<Book>> books = new MutableLiveData<>();

public void getBooks(String bookName, int maxResult){

    BookClient.getInstance().getBooks(bookName,maxResult).enqueue(new Callback<JsonObject>() {
        @Override
        public void onResponse(Call<JsonObject> call, Response<JsonObject> response) {
             List<Book> dataSet = new ArrayList<>();

            if (!response.isSuccessful()) {
                Log.d(TAG, "Code: " + response.code());
                return;
            }

            try {
                JsonObject root = response.body();
                JsonArray booksArray = root.getAsJsonArray("items");
                for (int i=0; i<booksArray.size(); i++){
                    JsonObject currentObject = booksArray.get(i).getAsJsonObject();
                    JsonObject info = currentObject.getAsJsonObject("volumeInfo");
                    JsonElement bookTitle = info.get("title");
                    if(info.has("averageRating") && info.has("description")){
                        JsonElement bookDescription= info.get("description");
                        JsonElement bookRating = info.get("averageRating");
                        JsonElement bookURL = info.get("infoLink");
                        JsonElement bookRatingReviews = info.get("ratingsCount");
                        JsonElement bookPageCount = info.get("pageCount");
                        String bookCategories= "";
                        if(info.has("categories")){
                            JsonArray categories = info.getAsJsonArray("categories");
                            JsonElement bookCategoriesElement = categories.get(0);
                            bookCategories = bookCategoriesElement.getAsString();
                        }

                        JsonObject imageLinks = info.getAsJsonObject("imageLinks");
                        JsonElement bookThumbnail = imageLinks.get("thumbnail");
                        JsonElement bookPublishedDate = info.get("publishedDate");
                        JsonElement bookAuthor;
                        if(info.has("authors")){
                            JsonArray authors = info.getAsJsonArray("authors");
                            bookAuthor = authors.get(0);
                        }else
                            bookAuthor = info.get("publisher");

                        dataSet.add(new Book(bookTitle.getAsString(),
                                bookAuthor.getAsString(),
                                bookDescription.getAsString(),
                                bookThumbnail.getAsString(),
                                bookURL.getAsString(),
                                bookCategories,
                                bookPublishedDate.getAsString(),
                                bookRating.getAsDouble(),
                                bookRatingReviews.getAsInt(),
                                bookPageCount.getAsInt()));
                        Log.d("boss", "onResponse: "+ bookAuthor.getAsString());
                    }

                }
            }catch (JsonParseException e){
                Log.e(TAG, "Problem parsing the book JSON results", e);
            }

            books.setValue(dataSet);
            Log.d("boss", "getBooks: "+ dataSet.size() + dataSet.get(0).getAuthor());

        }

        @Override
        public void onFailure(Call<JsonObject> call, Throwable t) {
            Log.d(TAG, "onFailure: " + t.getMessage());
        }
    });

}//getBooks

}//BookViewModel

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