Android中利用泛型简化MVP

简介

封装MvpFragment以及MvpPresenter，简化MVP的构建，达到偷懒的目的。
能够参考以前的另外一篇文章:
Android Mvp实践

最终使用效果

Fragment和Presenter只需分别继承MvpFragmen、MvpPresenter便可进行绑定。

Activity

Activity容器,里面放置了两个Fragment，在activity中将Fragment和其present绑定。

@EActivity(R.layout.activity_main)
public class MainActivity extends AppCompatActivity {
    FragmentManager fm;
    private Fragment mFragmentNow;
    MapFragment mapFragment  = new MapFragment_();
    UserFragment userFragment = new UserFragment_();

    @Bean
    MapPresenter mapPresenter;

    @Bean
    UserPresenter userPresenter;

    @AfterViews
    void init() {
        setDefaultFragment();
        mapPresenter.setView(this, mapFragment); //view和presenter绑定
        userPresenter.setView(this, userFragment);//view和presenter绑定
    }

    private void setDefaultFragment() {
        fm = getFragmentManager();
        FragmentTransaction transaction = fm.beginTransaction();
        transaction.add(R.id.fragcontent, mapFragment);
        transaction.commit();
        mFragmentNow = mapFragment;
    }

    private void switchContent(Fragment from, Fragment to) {
        if (mFragmentNow != to) {
            mFragmentNow = to;
            FragmentTransaction transaction = fm.beginTransaction();
            if (!to.isAdded()) {    // 先判断是否被add过
                transaction.hide(from).add(R.id.fragcontent, to).commit(); // 隐藏当前的fragment，add下一个到Activity中
            } else {
                transaction.hide(from).show(to).commit(); // 隐藏当前的fragment，显示下一个
            }
        }
    }
//点击切换fragment略..
}复制代码

Contract

Presenter和View的接口

public class MapContract {

    public interface View extends BaseView<Presenter> {
     //...
    }

    public interface Presenter extends BasePresenter {
     //...
    }

}复制代码

View层

@EFragment(R.layout.fragment_map)
public class MapFragment extends MvpFragment<MapContract.Presenter> implements MapContract.View{
   //...实现接口中的方法
}复制代码

Presenter层

@EBean
public class MapPresenter extends MvpPresenter<MapContract.View> implements MapContract.Presenter {
   //...实现接口中的方法
}复制代码

这样，简单地就将Presenter层和View关联起来，在各自的层中处理不一样的业务。

实现过程

base类

public interface BaseView<T> {
    void setPresenter(T presenter);
}复制代码

public interface BasePresenter {

}复制代码

MvpFragment

经过泛型传入Presenter，并覆写BaseView中的setPresenter

public class MvpFragment <P extends BasePresenter> extends Fragment implements BaseView<P>{
    public P mPresenter;

    @Override
    public void setPresenter(BasePresenter presenter) {
        if (presenter != null)
            mPresenter = (P) presenter;
    }
}复制代码

MvpPresenter

经过泛型传入BaseView,实现setView方法

public class MvpPresenter <V extends BaseView> {
    public Context context;
    public V mView;

    public void setView(Context context, V mView) {
        this.context = context;
        this.mView = mView;
        mView.setPresenter(this);
    }

}复制代码

小结

经过以上方法，Activity中调用mapPresenter.setView(this, mapFragment)将view传入，而在setView中又调用setPresenter将view和Presenter绑定，因而能够在view层和presenter调用相关接口。