转载请标明出处：http://www.jianshu.com/p/651146bd0688
本文出自:Jlanglang

基类:

在开发中有着很重要的地位,基类设计封装的好,不管是对app的性能,还是对开发的效率都有着很重要的作用

基类可以简单几个字概况,一个良好的父类.

结构:

不管你的app是多个acitivity,还是1个activity+n个fragment,还是多个acitivity多个fragment.

始终都是用的acitivity和fragment.

根据项目的不同,基类不可能完全相同,但很多还是可以通用的.

抽取:

既然是mvp,那么不管是acitivity还是fragment.都归于v
既然是v,那么就应该有相对应的presenter,view
那么基类应该有:
BaseActivityView
BaseFragmentView
BaseView
BasePresenter

具体代码:

BaseActivity

public abstract class BaseActivity<T extends BasePresenter> extends AppCompatActivity implements BaseActivityView {

    protected T mPresenter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //创建Presenter
        mPresenter = initPresenter();
        //类似fragment的绑定.拿到引用
        mPresenter.onAttch(this);
        //初始化acitivity,
        onCreateActivity(savedInstanceState);
        //初始化Presenter
        mPresenter.onCreate();
    }


    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        mPresenter.onSaveInstanceState(outState);
    }

    @Override
    protected void onDestroy() {
        mPresenter.onDestroy(); 
        mPresenter.onDetach();
        super.onDestroy();
    }

    @Override
    public BaseActivity getActivity() {
        return this;
    }

    /**
     * 创建prensenter
     * @return <T extends BasePresenter> 必须是BasePresenter的子类
     */
    protected abstract T initPresenter();

    /**
     * 子类必须实现,并初始化Activity,比如setContentView()
     */
    protected abstract void onCreateActivity(Bundle savedInstanceState);
    @Override
    public void isNightMode(boolean isNight) {

    }
}

BaseFragment

稍微复杂一点.

public abstract class BaseFragment<T extends BasePresenter> extends Fragment implements BaseFragmentView {
    protected T mPresenter;
    protected Context mContext;//activity的上下文对象
    protected Bundle mBundle;

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        if (mBundle != null) {
            outState.putBundle("bundle", mBundle);
        }
    }
    /**
     * 绑定activity
     *
     * @param context
     */
    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        mContext = context;
    }

    /**
     * 运行在onAttach之后
     * 可以接受别人传递过来的参数,实例化对象.
     *
     * @param savedInstanceState
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //获取bundle,并保存起来
        if (savedInstanceState != null) {
            mBundle = savedInstanceState.getBundle("bundle");
        } else {
            mBundle = getArguments() == null ? new Bundle() : getArguments();
        }
        //创建presenter
        mPresenter = initPresenter();
    }

    /**
     * 运行在onCreate之后
     * 生成view视图
     */
    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        return initView(inflater, container, savedInstanceState);
    }

    /**
     * 运行在onCreateView之后
     * 加载数据
     */
    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        //由于fragment生命周期比较复杂,所以Presenter在onCreateView创建视图之后再进行绑定,不然会报空指针异常
        mPresenter.onAttch(this);
        mPresenter.onCreate();
    }

    @Override
    public void onDestroyView() {
        mPresenter.onDestroy();
        super.onDestroyView();
    }
    @Override
    public void onDetach() {
        mPresenter.onDetach();
        super.onDestroyView();
    }
    /**
     * 跳转fragment
     *
     * @param tofragment
     */
    @Override
    public void startFragment(Fragment tofragment) {
        startFragment(tofragment, null);
    }

    /**
     * @param tofragment 跳转的fragment
     * @param tag        fragment的标签
     */
    @Override
    public void startFragment(Fragment tofragment, String tag) {
        FragmentTransaction fragmentTransaction = getFragmentManager().beginTransaction();
        fragmentTransaction.hide(this).add(android.R.id.content, tofragment, tag);
        fragmentTransaction.addToBackStack(tag);
        fragmentTransaction.commitAllowingStateLoss();
    }

    /**
     * 类似Activity的OnBackgress
     * fragment进行回退
     */
    public void onBack() {
        getFragmentManager().popBackStack();
    }

    /**
     * 初始化Fragment应有的视图
     *
     * @return
     */
    public abstract View initView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState);

    /**
     * 创建prensenter
     *
     * @return <T extends BasePresenter> 必须是BasePresenter的子类
     */
    public abstract T initPresenter();

    @Override
    public Context getContext() {
        return mContext;
    }

    @Override
    public Bundle getBundle() {
        return mBundle;
    }

    @Override
    public BaseFragment getFragment() {
        return this;
    }

}

再看看BaseView

public interface BaseView {
    /**
     * 切换夜间模式
     * @param isNight 是否切换为夜间模式
     */
    void isNightMode(boolean isNight);
}

BaseView得想好做什么事,必须是你的项目里所有view都有的共性

不仅是acitivity和fragment,还有控件

-----------------------------------------------------------------------------------------------------

关键的BasePresenter来了

/**
 * @author jlanglang  2016/11/11 15:10
 */
public abstract class BasePresenter<T extends BaseView> {
   protected T mView;

    /**
     * 绑定View
     */
    public void onAttch(T view) {
        this.mView = view;
      
    }
    /**
     * 做初始化的操作,需要在V的视图初始化完成之后才能调用
     * presenter进行初始化.
     */
    public abstract void onCreate();
    /** 
    * 在这里结束异步操作
    */
    public void onDestroy(){

    }
    /**
     * 在V销毁的时候调用,解除绑定
    */
    public void onDetach() {  
       mView = null;
    }
    /**
    * 容易被回收掉时保存数据
    */
    public abstract void onSaveInstanceState(Bundle outState);
}

看看Acitivity的使用:

//创建的时候写好泛型实现好抽象方法就行,多么简单.
public class MainActivity extends BaseActivity<MainActivityPresenterImpl> implements MainActivityContract.View {
    @Override
    protected MainActivityPresenterImpl initPresenter() {
        return new MainActivityPresenterImpl();
    }

    @Override
    protected void onCreateActivity(Bundle savedInstanceState) {
        setContentView(R.layout.activity_main);
    }
}

最后是对应的MainActivityPresenterImpl以及MainActivityContract

public class MainActivityPresenterImpl extends BasePresenter<MainActivityContract.View>
 implements MainActivityContract.Presenter {

    @Override
    public void onCreate() {

    }
    @Override
    public void onSaveInstanceState(Bundle outState) {

    }
}

public class MainActivityContract {
    public interface View extends BaseActivityView {
    }

    public interface Presenter{
    }

    public interface Model {
    }

}

总结:

对于BasePresenter一开始我是写成接口形式的,
后来使用过程中,发现很麻烦,每次绑定View,释放View都需要重复造轮子.
仔细想想,抽象类更合适,
每个Presenter继承BasePresenter,实现Contract中的接口为其补充

最后会发现,view和presenter的结构一样.基类作为复用,接口作为补充.

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