如何在 mvvm android 中处理异常并将该异常传递给我们的视图

Question

我正在使用 MVVM 架构通过在 android studio 中进行改造来实现 Web 服务。我已经在我的视图类中处理了服务的响应。但我面临的问题是如何处理异常并将它们传递给我的视图类。一种方法是在我的 Bean 类中创建构造函数并将响应和错误都传递给它并更新 UI。但我想要更优化的方式来处理 UI 内的异常。

这是我的存储库代码：

final MutableLiveData<MyBeanClass> myBeanClass = new MutableLiveData<>();ApiInterface apiInterface = ApiClient.getClientAuthentication().create(ApiInterface.class);
Call<MyBeanClass> call = apiInterface.getData(id);
call.enqueue(new Callback<MyBeanClass>() {@Override
    public void onResponse(Call<MyBeanClass> call, Response<MyBeanClass> response) {
        if(response.body()!=null) {
            myBeanClass.setValue(response.body());
        }
    }

    @Override
    public void onFailure(Call<MyBeanClass> call, Throwable t) {
     //How to handle exceptions here and pass the exception to UI without making constructor in bean class
    }
});

return myBeanClass;

Answer 1

您可以将 Bean 类包装在 Generic Resource 类中并观察它。谷歌在他们的文档中提到了它：

public class Resource<T> {

    @NonNull public final Status status;
    @Nullable public final T data;
    @Nullable public final String message;

    private Resource(@NonNull Status status, @Nullable T data,
            @Nullable String message) {
        this.status = status;
        this.data = data;
        this.message = message;
    }

    public static <T> Resource<T> success(@NonNull T data) {
        return new Resource<>(Status.SUCCESS, data, null);
    }

    public static <T> Resource<T> error(String msg, @Nullable T data) {
        return new Resource<>(Status.ERROR, data, msg);
    }

    public static <T> Resource<T> loading(@Nullable T data) {
        return new Resource<>(Status.LOADING, data, null);
    }

    public enum Status { SUCCESS, ERROR, LOADING }
}

更多可以在这里找到：Google Docs

这样做：

final MutableLiveData<Resource<MyBeanClass>> myBeanClass = new MutableLiveData<>();
ApiInterface apiInterface = 
        ApiClient.getClientAuthentication().create(ApiInterface.class);

Call<Response<MyBeanClass>> call = apiInterface.getData(id);
call.enqueue(new Callback<Resource<MyBeanClass>>() {
    @Override
    public void onResponse(Call<MyBeanClass> call, 
            Response<Resource<MyBeanClass>> response) {
        if (response.body() != null) {
            myBeanClass.setValue(Resource.success(response.body()));
        }
    }

    @Override
    public void onFailure(Call<MyBeanClass> call, Throwable t) {
         myBeanClass.setValue(Resource.error(t.getMessage), null);
    }
});
return myBeanClass;

现在类似地，观察包装在 Resource 中的 ViewModel Bean 类。 根据资源类状态处理成功和错误