MVP实战心得(二)---Base基类的封装

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的与view进行绑定.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();
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);
//presenter进行初始化.
mPresenter.onCreate();
}

@Override
public void onDestroyView() {
mPresenter.onDestroy();
super.onDestroyView();
}

/**
* 跳转fragment
*
aa1e
* @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view的视图初始化完成之后才能调用
*/
public abstract void onCreate();

/**
* 默认在view销毁的时候调用,解除绑定
*在view销毁前释放presenter中的对象,资源.
*/
public void onDestroy() {
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

,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,写成抽象类更适合.

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.