Android 官方示例:android-architecture 学习笔记(二)之todo-mvp
项目地址:https://github.com/googlesamples/android-architecture/tree/todo-mvp/
在第一篇说过,todo-mvp只是android-architecture项目的一个分支
项目结构
todo-mvp主要使用了mvp架构来实现,如图
图中的Repository就是数据源,即M,包括Local数据和Remote数据;Fragment为V;Activity中依赖了P,V(Fragment)与P相互依赖,P依赖了M(Repository),即P分离了M与V;当然有时我们不需要Fragment,那么可以直接使用Activity来作为V
项目的主要包结构及Base接口
(不含测试package):
除BaseView、BasePresenter两个接口,其他package都以业务功能来划分的:
addedittask —— 添加任务
data —— 数据源
statistics —— 任务统计
taskdetail —— 任务详情
tasks —— 任务列表
util —— 工具类
BaseView、BasePresenter两个接口:
public interface BaseView { void setPresenter(T presenter);}public interface BasePresenter { void start();}
数据源Model
先来看下data模块,即M
Task —— 它就是一个java bean
TasksDataSource —— Task数据操作的接口
TasksRepository —— 实现了TasksDataSource,依赖了TasksLocalDataSource、TasksRemoteDataSource,实现根据不同情形,获取Local或Remote的相关数据
TasksRemoteDataSource —— 远程数据,一般可能走网络,当然这里没有,只是模拟
TasksPersistenceContract —— 约定了数据库表字段
TasksDbHelper —— 数据库操作
TasksLocalDataSource —— 本地数据源
注:项目中默认只操作了Local数据,若也想操作Remote,只需要将TasksRepository中的属性mCacheIsDirty=true,即可
tasks模块分析
接下来挑一个业务模块分析一下(其它模块大同小异),比如tasks
ScrollChildSwipeRefreshLayout —— 这是一个自定义Layout,不用理会
TasksActivity —— Activity
TasksContract —— 契约接口(每个功能模块都有一个),约定了两个子接口View和Presenter,及各自的公共方法;分别实现BaseView、BasePresenter两个接口
TasksFilterType —— enum类,任务过滤类型
TasksFragment —— Fragment,实现TasksContract.View
TasksPresenter —— Presenter,实现TasksContract.Presenter
再来分析一个具体的业务功能,比如展示tasks列表
在TasksContract#Presenter中,有一个方法:
void loadTasks(boolean forceUpdate);
相应的TasksContract#View中,有一个方法:
void showTasks(List<Task> tasks);
看下TasksPresenter的相关的一些代码:
public class TasksPresenter implements TasksContract.Presenter { private final TasksRepository mTasksRepository; private final TasksContract.View mTasksView; private TasksFilterType mCurrentFiltering = TasksFilterType.ALL_TASKS; private boolean mFirstLoad = true; public TasksPresenter(@NonNull TasksRepository tasksRepository, @NonNull TasksContract.View tasksView) { mTasksRepository = checkNotNull(tasksRepository, "tasksRepository cannot be null"); mTasksView = checkNotNull(tasksView, "tasksView cannot be null!"); mTasksView.setPresenter(this); } @Override public void start() { loadTasks(false); } @Override public void loadTasks(boolean forceUpdate) { // Simplification for sample: a network reload will be forced on first load. loadTasks(forceUpdate || mFirstLoad, true); mFirstLoad = false; } private void loadTasks(boolean forceUpdate, final boolean showLoadingUI) { if (showLoadingUI) { mTasksView.setLoadingIndicator(true); } if (forceUpdate) { mTasksRepository.refreshTasks(); } // The network request might be handled in a different thread so make sure Espresso knows // that the app is busy until the response is handled. EspressoIdlingResource.increment(); // App is busy until further notice mTasksRepository.getTasks(new TasksDataSource.LoadTasksCallback() { @Override public void onTasksLoaded(List tasks) { List tasksToShow = new ArrayList(); // This callback may be called twice, once for the cache and once for loading // the data from the server API, so we check before decrementing, otherwise // it throws "Counter has been corrupted!" exception. if (!EspressoIdlingResource.getIdlingResource().isIdleNow()) { EspressoIdlingResource.decrement(); // Set app as idle. } // We filter the tasks based on the requestType for (Task task : tasks) { switch (mCurrentFiltering) { case ALL_TASKS: tasksToShow.add(task); break; case ACTIVE_TASKS: if (task.isActive()) { tasksToShow.add(task); } break; case COMPLETED_TASKS: if (task.isCompleted()) { tasksToShow.add(task); } break; default: tasksToShow.add(task); break; } } // The view may not be able to handle UI updates anymore if (!mTasksView.isActive()) { return; } if (showLoadingUI) { mTasksView.setLoadingIndicator(false); } processTasks(tasksToShow); } @Override public void onDataNotAvailable() { // The view may not be able to handle UI updates anymore if (!mTasksView.isActive()) { return; } mTasksView.showLoadingTasksError(); } }); } private void processTasks(List tasks) { if (tasks.isEmpty()) { // Show a message indicating there are no tasks for that filter type. processEmptyTasks(); } else { // Show the list of tasks mTasksView.showTasks(tasks); // Set the filter label's text. showFilterLabel(); } }}
从上,看出TasksPresenter依赖了TasksRepository、TasksContract.View,即P依赖了M和V;当loadTasks(boolean forceUpdate, final boolean showLoadingUI)被调用后,先从M中获取数据,再调用processTasks(List tasks),其内部调用mTasksView.showTasks(tasks)将数据显示在V上;最后还要说的一点是在TasksPresenter的构造方法中,mTasksView.setPresenter(this) 将P传递给了V
再来看下V如何通过P,来获取数据并显示
TasksFragment,即V的主要代码:
public class TasksFragment extends Fragment implements TasksContract.View { private TasksContract.Presenter mPresenter; public TasksFragment() { // Requires empty public constructor } public static TasksFragment newInstance() { return new TasksFragment(); } @Override public void onCreate(@Nullable Bundle savedInstanceState) { super.onCreate(savedInstanceState); mListAdapter = new TasksAdapter(new ArrayList(0), mItemListener); } @Override public void onResume() { super.onResume(); mPresenter.start(); } @Override public void setPresenter(@NonNull TasksContract.Presenter presenter) { mPresenter = checkNotNull(presenter); } @Nullable @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() { @Override public void onRefresh() { mPresenter.loadTasks(false); } }); return root; } @Override public void showTasks(List tasks) { mListAdapter.replaceData(tasks); mTasksView.setVisibility(View.VISIBLE); mNoTasksView.setVisibility(View.GONE); }}
看TasksFragment的onResume()中,调用了mPresenter.start(),而mPresenter.start()中,就调用了TasksPresenter#loadTasks(false);TasksFragment的onCreateView()中还注册了一个监听回调,即下拉刷新时,也会调用TasksPresenter#loadTasks(false);
P和V的初始化在Activity中完成
TasksActivity的主要代码:
public class TasksActivity extends AppCompatActivity { private TasksPresenter mTasksPresenter; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.tasks_act); TasksFragment tasksFragment = (TasksFragment) getSupportFragmentManager().findFragmentById(R.id.contentFrame); if (tasksFragment == null) { // Create the fragment tasksFragment = TasksFragment.newInstance(); ActivityUtils.addFragmentToActivity( getSupportFragmentManager(), tasksFragment, R.id.contentFrame); } // Create the presenter mTasksPresenter = new TasksPresenter( Injection.provideTasksRepository(getApplicationContext()), tasksFragment); // Load previously saved state, if available. if (savedInstanceState != null) { TasksFilterType currentFiltering = (TasksFilterType) savedInstanceState.getSerializable(CURRENT_FILTERING_KEY); mTasksPresenter.setFiltering(currentFiltering); } }}
至此,一条完整的MVP架构实现的业务链就分析完成了
更多相关文章
- Android8.1添加MTP数据同步操作
- android - SAX解析XML数据
- Android客户端向服务器端发送数据的流程(1)
- Android的数据存储之一------SharedPreferences
- Android数据绑定Data Binding初体验