通过mvvm android进行异常处理

Question

我正在使用MVVM架构通过android studio中的改造来获得Web服务。我在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

你可以在这里接口。从onFailure调用接口方法并从UI端提供该接口的实现，因此每当出现错误时，yiu将进入UI端

Answer 2

看看如何从您的存储库代码中完成它：

//Take it globally in your repository class, and provide getter for it.
final MutableLiveData<MyBeanClass> myBeanClass = new MutableLiveData<>();
final MutableLiveData<Throwable> error = new MutableLiveData<>();

public void someApiCallMethod() {
    // In your method call for API
    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());
            }
            // Even you can handle your response error if it's in your response.
        }

        @Override
        public void onFailure(Call<MyBeanClass> call, Throwable t) {
            //Set your error live data from here
            error.setValue(t);
        }
    });
}

在ViewModel类中，创建一个调用repo API方法的方法，另一个方法用于提供在UI上观察的实时数据。

希望能帮助到你 ！。

Answer 3

而不是创建两个Mutable类。您可以为错误和成功状态甚至加载状态创建包装器对象

data class Resource<out T>(val status: Status, val data: T?, val message: String?) {
    companion object {
        fun <T> success(data: T?): Resource<T> {
            return Resource(SUCCESS, data, null)
        }

        fun <T> error(msg: String, data: T?): Resource<T> {
            return Resource(ERROR, data, msg)
        }

        fun <T> loading(data: T?): Resource<T> {
            return Resource(LOADING, data, null)
        }
    }
}

然后使用MutableLive数据作为此类型

final MutableLiveData<Resource<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(Resource<MyBeanClass>.success(response.body));
                    }
                }

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

            return myBeanClass;

你可以查看这个谷歌样本https://github.com/googlesamples/android-architecture-components/tree/master/GithubBrowserSample