1. Introduction

Recently, we developed a very simple APP based on Wanandroid open API, using the model of Androidx + MVVM + Retrofit + dataBinding for development. The main function of the App is to browse various Android articles, as shown below:

1.1 Functional renderings display

The home page	project	Wechat official account	The knowledge system

The article details	my	registered	navigation

1.2 Project design mode

This project adopts the MVVM development mode, about the MVVM development mode, you can refer to: How to build the Android MVVM application framework, if you think it is not easy to understand, you can refer to the Android MVC MVP MVVM simple example

Typical architecture diagram of MVVM:Architecture diagram of the project:

2. Code parsing

For example: our home page, with banner advertising picture and homepage article, as shown below:

So to do this, we need to create HomeViewModel, HomeRepository, and HomeBeanFiles for HomeFragment, as follows:

See Wanandroid_Learning for the code

HomeFragment.java

public class HomeFragment extends Fragment {
    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        / / create the ViewModel
        HomeViewModel homeVm = ViewModelProviders.of(this.new ViewModelFactory()).get(HomeViewModel.class);
        // Observe banner data
        homeVm.getHomeBannerListLd().observe(getViewLifecycleOwner(), bannerListDataObserver);
        homeVm.setHomeBannerListLd();
        // View Article datahomeVm.getHomeArticleListBeanLd().observe(getViewLifecycleOwner(), articleListBeanObserver); homeVm.setHomeArticleListBeanLd(); } ··· slightly ··}Copy the code

HomeViewModel.java

public class HomeViewModel extends ViewModel {
    private static final String TAG = "HomeViewModel";
    private MutableLiveData<HomeBannerListBean> homeBannerListLd;
    private MutableLiveData<HomeArticleListBean> homeArticleListBeanLd;

    public HomeViewModel(a) {
        this.homeBannerListLd = new MutableLiveData<>();
        this.homeArticleListBeanLd = new MutableLiveData<>();
    }

    public MutableLiveData<HomeBannerListBean> getHomeBannerListLd(a) {
        return homeBannerListLd;
    }

    public void setHomeBannerListLd(a) {
        HomeRepository.newInstance().getHomeBannerList(new GetWebDataListener() {
            @Override
            public void getDataSuccess(Object object) {
                HomeBannerListBean homeBannerListBean = (HomeBannerListBean) object;
                homeBannerListLd.postValue(homeBannerListBean);
            }

            @Override
            public void getDataFailed(String failedMsg) {
                Log.e(TAG, "getDataFailed: "+ failedMsg); }}); }public MutableLiveData<HomeArticleListBean> getHomeArticleListBeanLd(a) {
        return homeArticleListBeanLd;
    }

    public void setHomeArticleListBeanLd(a) {
        HomeRepository.newInstance().getHomeArticleList(0.new GetWebDataListener() {
            @Override
            public void getDataSuccess(Object object) {
                HomeArticleListBean homeArticleListBean = (HomeArticleListBean) object;
                homeArticleListBeanLd.postValue(homeArticleListBean);
            }

            @Override
            public void getDataFailed(String failedMsg) {
                Log.e(TAG, "getDataFailed: "+ failedMsg); }}); }}Copy the code

HomeRepository.java

public class HomeRepository {
    /** * The volatile keyword is used to prevent DCL failures. * /
    private volatile static HomeRepository instance;

    public static HomeRepository newInstance(a) {
        if (instance == null) {
            synchronized (HomeRepository.class) {
                if (instance == null) {
                    instance = newHomeRepository(); }}}return instance;
    }

    public void getHomeBannerList(final GetWebDataListener listener) {
        ApiService apiService = ApiWrapper.getRetrofitInstance().create(ApiService.class);
        apiService.getHomeBannerList().enqueue(new AbstractRetrofitCallback() {
            @Override
            public void getSuccessful(String responseBody) {
                Gson gson = new Gson();
                HomeBannerListBean homeBannerListBean = gson.fromJson(responseBody, HomeBannerListBean.class);
                listener.getDataSuccess(homeBannerListBean);
            }

            @Override
            public void getFailed(String failedMsg) { listener.getDataFailed(failedMsg); }}); }public void getHomeArticleList(int pageNumber, final GetWebDataListener listener) {
        ApiService apiService = ApiWrapper.getRetrofitInstance().create(ApiService.class);
        apiService.getHomeArticleList(pageNumber).enqueue(new AbstractRetrofitCallback() {
            @Override
            public void getSuccessful(String responseBody) {
                Gson gson = new Gson();
                HomeArticleListBean homeArticleListBean = gson.fromJson(responseBody, HomeArticleListBean.class);
                listener.getDataSuccess(homeArticleListBean);
            }

            @Override
            public void getFailed(String failedMsg) { listener.getDataFailed(failedMsg); }}); }}Copy the code

See Wanandroid_Learning for the code

Kotlin version

At the same time, in order to learn Kotlin, I also developed Kotlin version, also using MVVM development mode, see the specific code: Wanandroid_Learning_Kotlin

Project effect screenshot display:

The home page	project	Wechat official account	The knowledge system

The article details	my	Log in to	navigation

Flutter version

Now a version of Flutter has been developed, see my other article Wanandroid Flutter version

Effect display:

Again: the API of this project is from Teacher Hong Yang’s Wanandroid open API. Thanks again for teacher Hong Yang’s open source sharing.

In fact, the biggest purpose of sharing articles is to wait for someone to point out my mistakes. If you find any mistakes, please point them out without reservation and consult with an open mind.

Welcome to study and discuss, peace~