Android(安卓)MVP开发模式实践

MVP模式概念

在MVP模式里通常包含4个要素：

View:负责绘制UI元素、与用户进行交互(在Android中体现为Activity);
View interface:需要View实现的接口，View通过View interface与Presenter进行交互，降低耦合，方便进行单元测试;
Model:负责存储、检索、操纵数据(有时也实现一个Model interface用来降低耦合);
Presenter:作为View与Model交互的中间纽带，处理与用户交互的负责逻辑。

在Android开发中，Activity并不是一个标准的MVC模式中的Controller，它的首要职责是加载应用的布局和初始化用户界面，并接受并处理来自用户的操作请求，进而作出响应。随着界面及其逻辑的复杂度不断提升，Activity类的职责不断增加，以致变得庞大臃肿。
当我们将其中复杂的逻辑处理移至另外的一个类（Presneter）中时，Activity其实就是MVP模式中 View，它负责UI元素的初始化，建立UI元素与Presenter的关联（Listener之类），同时自己也会处理一些简单的逻辑（复杂的逻辑交由 Presenter处理）。

MVP与MVC模式对比

MVP模式：

View不直接与Model交互，而是通过与Presenter交互来与Model间接交互
Presenter与View的交互是通过接口来进行的，更有利于添加单元测试
通常View与Presenter是一对一的，但复杂的View可能绑定多个Presenter来处理逻辑

MVC模式：

View可以与Model直接交互
Controller是基于行为的，并且可以被多个View共享

MVP项目代码组织方式

项目含一个app src目录，4个测试目录：

测试目录
分别是androidTest（UI层测试）、androidTestMock（UI层测试mock数据支持）、test（业务层单元测试）、mock（业务层单元测试mock数据支持）。
src目录

按照功能组织，功能内部分为xactivity、xcontract、xfragment、xpresenter四个类文件(x代表业务名称)；
按照类型组织，比如按照activity、adapter、fragment、contract、presenter进行划分，不同的类文件分别放到不同的目录中。

MVP具体应用实现

/** * mvp 中的 v */public interface IView {    /**     * 添加 presenter     */    void addPresenter(IPresenter presenter);    /**     * 结束当前view     */    void finish();}

/** * mvp中的P */public interface IPresenter {    /**     * 回调   * @return true,已经处理.     */    boolean onActivityResult(int requestCode, int resultCode, Intent data);    /**     * 注册广播   */    String[] registerLocalReceivers();    /**     * 接收到广播   */    void onLocalReceive(Intent intent);    /**     * UI销毁,释放view     */    void onDestroyView();}

```java /** * 业务处理基类 */ public abstract class AbsPresenter implements IPresenter {

protected AppCompatActivity mActivity;protected Context mContext;protected LoaderManager mLoaderManager;public AbsPresenter(@NonNull IView view) {    if (view instanceof AppCompatActivity) {        initWithActivity((AppCompatActivity) view);    } else if (view instanceof Fragment) {        initWithFragment((Fragment) view);    } else if (view instanceof ActivityInstrumentationTestCase2) {        ActivityInstrumentationTestCase2 testCase = (ActivityInstrumentationTestCase2) view;        mContext = testCase.getActivity();        mActivity = (AppCompatActivity) testCase.getActivity();        mLoaderManager = mActivity.getSupportLoaderManager();    } else {        throw new RuntimeException("view must be instance of AppCompatActivity or Fragment.");    }}private void initWithActivity(AppCompatActivity activity) {    mActivity = activity;    mContext = mActivity;    mLoaderManager = mActivity.getSupportLoaderManager();}private void initWithFragment(Fragment fragment) {    mActivity = (AppCompatActivity) fragment.getActivity();    mContext = fragment.getContext();    mLoaderManager = fragment.getLoaderManager();}@Overridepublic boolean onActivityResult(int requestCode, int resultCode, Intent data) {    return false;}@Overridepublic String[] registerLocalReceivers() {    return new String[0];}@Overridepublic void onLocalReceive(Intent intent) {}@Override@CallSuperpublic void onDestroyView() {    mActivity = null;    mContext = null;    mLoaderManager = null;}

}



------MVP中的M也就是Model层一般和Bean实体会抽离出来，作为中间件接口调用，如ModelService Module------

实现某个具体业务流程如下：1. 定义某个业务Presenter接口IXxPresenter extends IPresenter2. 定义某个业务显示View接口IXxView extends IView3. 实现某个业务Presenter--XxPresenter(增删查改) ```javapublic class XxPresenter extends AbsPresenter implements IXxPresenter, LoaderManager.LoaderCallbacks {    private IXxView mView;    private XxTask mXxTask;    public XxPresenter(@NonNull IXxView view) {        super(view);        mView = view;    }    @Override    public Loader onCreateLoader(int id, Bundle args) {        //返回一个new CursorLoader对象    }    @Override    public void onLoadFinished(Loader loader, Cursor data) {        //完成对UI主界面的更新        if (mView != null) {            mView.showXx();        }    }    @Override    public void onLoaderReset(Loader loader) {    }    @Override    public void queryXx() {        mLoaderManager.destroyLoader(AppConst.LOADER_ID.XXX);        mLoaderManager.initLoader(AppConst.LOADER_ID.XXX, null, this);    }    @Override    public void updateXx() {        if (mXxTask == null || mXxTask.getStatus() != AsyncTask.Status.RUNNING) {            mXxTask = new XxTask();            mXxTask.execute();        }    }    //deleteXx    //saveXx(insert && update,根据是否有有效ID值判断)    private void destroyLoader() {        mLoaderManager.destroyLoader(AppConst.LOADER_ID.XXX);        mLoaderManager.destroyLoader(AppConst.LOADER_ID.YYY);    }    @Override    public void onDestroyView() {        destroyLoader();        if (mXxTask != null) {            mXxTask.cancel(true);            mXxTask = null;        }        mView = null;        super.onDestroyView();    }    private class XxTask extends AsyncTask {        private xx;        private xxx;        XxTask() {            //初始化成员变量        }        @Override        protected Boolean doInBackground(Void... params) {            //返回类型自定义        }        @Override        protected void onPostExecute(Boolean res) {            super.onPostExecute(res);            if (mView != null) {                mView.showXx();            }        }    }}

Presenter工具类 ```java /** * 用于绑定presenter */ public class Presenter { // 负责生成Presenter的工厂类 private static IPresenterFactory sPresenterFactory;

private Presenter() {    // do nothing}/** * 初始化此Presenter类 */public static void init(@NonNull IPresenterFactory factory) {    sPresenterFactory = factory;}/** * view与presenter进行绑定 * @param view 当前进行绑定的view */public static void bind(@NonNull IView view, Class ...clazzs) {    if (sPresenterFactory == null) {        throw new RuntimeException("must invoke Presenter.init() to init IPresenterFactory first!");    }    for (Class clazz : clazzs) {        IPresenter presenter = sPresenterFactory.newPresenter(view, clazz);        if (presenter != null) {            view.addPresenter(presenter);        }    }}

}



Presenter实例化
```java/** * Presenter工厂,用于实例化相应的Presenter */public interface IPresenterFactory {    /**     * 返回Presenter实现类的实例   */    @Nullable    IPresenter newPresenter(IView view, Class clazz);}

```java /** * Presenter实例化工厂 */ public class PresenterFactory implements IPresenterFactory {

@Nullable@Overridepublic IPresenter newPresenter(IView view, Class clazz) {    final String className = clazz.getName();    IPresenter presenter = null;        if (view instanceof IXxView && className.equals(IXxPresenter.class.getName())) {        IXxView xxView = (IXxView) view;        return new XxPresenter(xxView);    }  }

}




```java/** * app application */public class XxApplication extends ApplicationWrapper {    @Override    public void onCreate() {        super.onCreate();        ......        // presenter初始化     Presenter.init(new PresenterFactory());        ......    }}

Presenter与Activity绑定，Activity实现View接口 ```java /** * Activity基类 */ public abstract class BaseActivity extends AppCompatActivity {

protected Context mContext = this;protected ActionBar mActionBar;protected Toolbar mToolbar;protected TextView mTitleTv;protected ImageView mIconIv;private List mPresenterList = new ArrayList<>();private BroadcastReceiver mReceiver;@Override@CallSuperprotected void onCreate(Bundle savedInstanceState) {    super.onCreate(savedInstanceState);    mReceiver = new BroadcastReceiver() {        @Override        public void onReceive(Context context, Intent intent) {            AppBarActivity.this.onLocalReceive(intent);        }    };    registerLocalReceiver();}@Override@CallSuperprotected void onDestroy() {    unregisterLocalReceiver();    for (IPresenter presenter : mPresenterList) {        presenter.onDestroyView();    }    super.onDestroy();}/** * 查找控件 */@CallSuperprotected void findWidget() {    mToolbar = (Toolbar) findViewById(R.id.toolbar);    mTitleTv = (TextView) findViewById(R.id.title_tv);    mIconIv = (ImageView) findViewById(R.id.logo_iv);}/** * 显示或隐藏标题图标,由子类去实现 */protected void showIcon(boolean show) {    if (show) {        mIconIv.setVisibility(View.VISIBLE);        mTitleTv.setVisibility(View.GONE);    } else {        mIconIv.setVisibility(View.GONE);        mTitleTv.setVisibility(View.VISIBLE);    }}/** * 设置标题 */public void setTitle(String title) {    mTitleTv.setText(title);}/** * 设置actionBar的显示和隐藏 */public void setActionBarVisibility(int visibility) {    mToolbar.setVisibility(visibility);}/** * 隐藏标题 */public void hideAppBar() {    if (mToolbar != null) {        mToolbar.setVisibility(View.GONE);    }}/** * 初始化控件 */protected void initWidget() {    if (mToolbar != null) {        setSupportActionBar(mToolbar);        mActionBar = getSupportActionBar();        if (mActionBar != null) {            mActionBar.setDisplayShowTitleEnabled(false);            mActionBar.setDisplayHomeAsUpEnabled(true);            mActionBar.setHomeAsUpIndicator(R.drawable.icon_back);        }    }}protected void setListener() {}@CallSuperpublic void addPresenter(IPresenter presenter) {    mPresenterList.add(presenter);}@Overridepublic boolean onOptionsItemSelected(MenuItem item) {    if (item.getItemId() == android.R.id.home) {        onBackPressed();        return true;    } else {        return super.onOptionsItemSelected(item);    }}@CallSuperprotected void onLocalReceive(Intent intent) {    for (IPresenter presenter : mPresenterList) {        presenter.onLocalReceive(intent);    }}@CallSuperprotected String[] registerLocalReceivers() {    ArrayList allActionList = new ArrayList<>();    List actionList;    for (IPresenter presenter : mPresenterList) {        actionList = Arrays.asList(presenter.registerLocalReceivers());        allActionList.addAll(actionList);    }    String[] actions = new String[allActionList.size()];    actions = allActionList.toArray(actions);    return actions;}private void registerLocalReceiver() {    LocalBroadcastManager localBroadcastManager = LocalBroadcastManager.getInstance(mContext);    IntentFilter intentFilter = new IntentFilter();    String[] actions = registerLocalReceivers();    for (String action : actions) {        intentFilter.addAction(action);    }    localBroadcastManager.registerReceiver(mReceiver, intentFilter);}private void unregisterLocalReceiver() {    LocalBroadcastManager localBroadcastManager = LocalBroadcastManager.getInstance(mContext);    localBroadcastManager.unregisterReceiver(mReceiver);}

}




```javaXxActivity extends BaseActivity implements IXxView, IXxxView, ...private IXxPresenter mXxPresenter;@Overrideprotected void onCreate(Bundle savedInstanceState) {    Presenter.bind(this, IXxPresenter.class, IXxxPresenter.class, ...);    super.onCreate(savedInstanceState);    //setContentView()    findWidget();    initWidget();    setListener();}@Overridepublic void addPresenter(IPresenter presenter) {    super.addPresenter(presenter);    if (presenter instanceof IXxPresenter) {        mXxPresenter = (IXxPresenter) presenter;    }...}/** * 初始化控件 */@Overrideprotected void initWidget() {    super.initWidget();    if(mXxPresenter != null) {                mXxPresenter.queryXx();//查询数据    }}@Overridepublic void showXx(params) {//传递数据//显示数据到UI界面}

MVP模式概念

MVP与MVC模式对比

MVP项目代码组织方式

MVP具体应用实现

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