Android之AAC架构尝试

一、AAC架构的前世今生

1、关于AAC需先了解一下Android Jetpack，Jetpack 是 Android 软件组件的集合，使您可以更轻松地开发出色的 Android 应用。这些组件可帮助您遵循最佳做法、让您摆脱编写样板代码的工作并简化复杂任务，以便您可以专注于您关心的代码。Jetpack 包含与平台 API 解除捆绑的 androidx.* 软件包库。这意味着，它提供向后兼容性并且比 Android 平台更频繁地更新，从而确保您始终可以获取最新且最好的 Jetpack 组件版本。

2、Android Jetpack的优势

（1）组件是为协同工作而构建的，不过也可以单独采用，同时利用 Kotlin 语言功能帮助您提高工作效率；

（2)Android Jetpack 可管理繁琐的 Activity（如后台任务、导航和生命周期管理），以便您可以专注于具体业务；

(3)Android Jetpack 组件围绕现代化设计实践构建而成，具有向后兼容性，可以减少崩溃和内存泄漏。

3、Android Architecture Components(简称AAC)，它是一套新的MVVM架构组件，使App的架构更加健壮,是Android Jetpack的架构组件具有可帮助管理界面组件生命周期、处理数据持久性等的类，以声明方式将可观察数据绑定到界面元素。

相关的API类：

二、代码实战

1、定义model类（省略get 、set方法）

public class NewsDataVo {    private String id;    private String newsTitle;    private String newsContent;    private String newsUrl;    private int readNum;}

2、定义ViewModel

public class NewsViewModel extends AndroidViewModel {    private MutableLiveData mData;    private LiveData switchDataMap;    LiveData getSwitchDataMap() {        return switchDataMap;    }    public NewsViewModel(@NonNull Application application) {        super(application);        mData = new MutableLiveData<>();        switchDataMap = Transformations.switchMap(mData, new Function>() {            @Override            public LiveData apply(NewsDataVo input) {                MutableLiveData temp = new MutableLiveData<>();                temp.setValue(input);                return temp;            }        });    }    /**     * 模拟获取网络数据     */    void httpGetData() {        int len = 10;        for (int i = 0; i < len; i++) {            NewsDataVo dataVo = new NewsDataVo();            dataVo.setId("1223" + i);            dataVo.setNewsTitle("Android AccArchitecture框架简介" + i);            dataVo.setNewsContent("Android Architecture Components,简称 AAC,一个处理UI的生命周期与数据的持久化的架构" + i);            dataVo.setReadNum(i);            mData.setValue(dataVo);        }    }}

3、定义LifecycleObserver管理View(Activity、Fragment)的生命周期

public class AccLifecycleObserver implements LifecycleObserver {    private Context context;    private String tag;    AccLifecycleObserver(Context context) {        this.context = context;        tag = context.getClass().getSimpleName();    }    @OnLifecycleEvent(Lifecycle.Event.ON_CREATE)    public void onCreate() {        Log.i(tag, "onCreate-----" + context.getClass());    }    @OnLifecycleEvent(Lifecycle.Event.ON_START)    public void onStart() {        Log.i(tag, "onStart-----" + context.getClass());    }    @OnLifecycleEvent(Lifecycle.Event.ON_RESUME)    public void onResume() {        Log.i(tag, "onResume-----" + context.getClass());    }    @OnLifecycleEvent(Lifecycle.Event.ON_PAUSE)    public void onPause() {        Log.i(tag, "onPause-----" + context.getClass());    }    @OnLifecycleEvent(Lifecycle.Event.ON_STOP)    public void onStop() {        Log.i(tag, "onStop-----" + context.getClass());    }    @OnLifecycleEvent(Lifecycle.Event.ON_DESTROY)    public void onDestroy() {        Log.i(tag, "onDestroy-----" + context.getClass());    }}

4、View层交互

public class MainActivity extends AppCompatActivity implements View.OnClickListener {    private MainActivity mActivity;    private NewsViewModel newsViewModel;    private DataAdapter dataAdapter;    private List mData;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initView();        addObserver();    }    @Override    public void onClick(View v) {        switch (v.getId()) {            case R.id.do_btn_tv:                newsViewModel.httpGetData();                break;            default:                break;        }    }    public void initView() {        mActivity = this;        mData = new ArrayList<>();        dataAdapter = new DataAdapter(mData);        findViewById(R.id.do_btn_tv).setOnClickListener(this);        RecyclerView recyclerView = findViewById(R.id.data_list_rv);        recyclerView.setHasFixedSize(true);        recyclerView.setLayoutManager(new LinearLayoutManager(mActivity));        recyclerView.setAdapter(dataAdapter);    }    private void addObserver() {        AccLifecycleObserver observer = new AccLifecycleObserver(mActivity);        getLifecycle().addObserver(observer);        ViewModelProvider.AndroidViewModelFactory instance = ViewModelProvider.AndroidViewModelFactory.getInstance(AccApp.sInstance);        newsViewModel = instance.create(NewsViewModel.class);        newsViewModel.getSwitchDataMap().observe(mActivity, new Observer() {            @Override            public void onChanged(@Nullable NewsDataVo dataVo) {                assert dataVo != null;                mData.add(dataVo);                dataAdapter.notifyDataSetChanged();            }        });    }    class DataAdapter extends RecyclerView.Adapter {        private List mData;        DataAdapter(List mData) {            this.mData = mData;        }        @NonNull        @Override        public ViewData onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {            return new ViewData(LayoutInflater.from(mActivity).inflate(R.layout.news_item, viewGroup, false));        }        @Override        public void onBindViewHolder(@NonNull ViewData viewData, int i) {            NewsDataVo newsDataVo = mData.get(i);            viewData.numTv.setText(newsDataVo.getReadNum() + "人阅读");            viewData.titleTv.setText(newsDataVo.getNewsTitle());            viewData.contentTv.setText(newsDataVo.getNewsContent());        }        @Override        public int getItemCount() {            return mData.size();        }        class ViewData extends RecyclerView.ViewHolder {            private ImageView imageView;            private TextView titleTv;            private TextView contentTv;            private TextView numTv;            public ViewData(@NonNull View itemView) {                super(itemView);                imageView = itemView.findViewById(R.id.image_iv);                titleTv = itemView.findViewById(R.id.title_tv);                contentTv = itemView.findViewById(R.id.content_tv);                numTv = itemView.findViewById(R.id.read_num_tv);            }        }    }

布局xml文件

<?xml version="1.0" encoding="utf-8"?>            <?xml version="1.0" encoding="utf-8"?>

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