对比MVC/MVP/MVVM
- MVC：经典的模式，model，view，controller，比较好理解，但是有些缺点，承担View角色的模块包含了过多的业务逻辑
- MVP：衍生于MVC，虽然View和业务解耦了，但是Presenter承担了太多任务
- MVVM：采用DataBinding，数据的渲染自动反映在ViewModel上，同时也可以通过ViewModel获取数据，但是业务处理堆在一块。
基于此，想让处理不同事情的模块独立起来，通过接口解耦，Presenter只负责remote data／native data的获取，然后由ViewModel把数据跟View绑定起来，汲取MVP和MVVM所长，于是有了MVPVM。
补充：对于架构模式的搭建，没法说哪种更好，只有哪种更合适，不要局限于架构，结合业务特性，现有的人力和任务时间（采用架构代码量一般会增加，但是结构会清晰），选取适合的框架。
MVPVM
参照MVP模式，采取contract接口隔离的方式，分离出View，Presenter，ViewWapper；Activity／Fragment实现View接口，提供Context下的API调用等，Presenter实现当前模块的业务数据获取，ViewWrapper则负责把数据传递给ViewModel实现数据绑定，以及View传递的Event处理。如下图：
mvp_vm_structure.jpg
抽离出Base类。
- BaseView ——— 抽象出来的需要Context环境的调用接口
- Presenter ——— 为实现架构搭建，由BasePresenter实现接口
- ViewWrapper ——— 为实现架构搭建，由BaseViewWrapper实现接口
- BaseActivity ——— 抽象出来的Base，即可由MvpVmActivity继承，也可由业务Activity继承
- BasePresenter ——— 抽象出来的MvpVm架构的Presenter基类
- BaseViewWrapper ——— 抽象出来的MvpVm架构的ViewWrapper基类
- MvpVmActivity ——— 抽象出来的MvpVm架构的Activity基类
- MvpVmFragment ——— 抽象出来的MvpVm架构的Fragment基类
- DemoActivity
BaseView
public interface BaseView {
public void setTitle(int titleId);
public void setTitle(String title);
public void showToast(int resId);
public void showToast(String msg);
public void showWaitDialog(int resId);
public void showWaitDialog(String message);
....
}
Presenter
public interface Presenter<V, VW> {
void attachView(V view);
void setViewWrapper(VW viewWrapper);
void detachView();
}
ViewWrapper
public interface ViewWrapper<V, D> {
void attachView(V view);
void detachView();
void setBinding(D dataBinding);
void onBind();
}
BaseActivity
public class BaseActivity<D extends ViewDataBinding> extends AppCompatActivity implements BaseView {
...
protected D dataBinding;
protected BaseActivity activity;
private BaseActivityDataBinding baseBinding;
protected <D extends ViewDataBinding> D generateDataBinding(@LayoutRes int layoutResID) {
D binding;
if (hasToolBar()) {
baseBinding = DataBindingUtil.setContentView(this, R.layout.activity_base);
...
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
binding = DataBindingUtil.inflate(inflater, layoutResID, baseBinding.contentLayout, true);
} else {
binding = DataBindingUtil.setContentView(this, layoutResID);
}
activity = this;
...
return binding;
}
}
generateDataBinding替换一般情况下调用的setContentView(int layoutId)，在业务Avtivity中第一步调用dataBinding = generateDataBinding(R.layout.xxx)即返回对应layout的DataBinding，用法后面demo中将会介绍。
BasePresenter
public class BasePresenter<V, VW> implements Presenter<V, VW> {
public V view;
protected VW viewWrapper;
...
@Override
public void attachView(V view) {
this.view = view;
}
@Override
public void setViewWrapper(VW viewWrapper) {
this.viewWrapper = viewWrapper;
}
@Override
public void detachView() {
view = null;
viewWrapper = null;
...
}
...
}
BaseViewWrapper
public class BaseViewWrapper<V, D extends ViewDataBinding> implements ViewWrapper<V, D> {
protected V view;
protected D dataBinding;
@Override
public void attachView(V view) {
this.view = view;
}
@Override
public void detachView() {
view = null;
if (dataBinding != null) {
dataBinding.unbind();
dataBinding = null;
}
}
@Override
public void setBinding(D dataBinding) {
this.dataBinding = dataBinding;
onBind();
}
@Override
public void onBind() {
}
}
onBind方法由业务ViewWrapper实现，具体操作为DataBinding的数据绑定，以及listener等事件的设置，会在后续博客中详细介绍。
MvpVmActivity
public abstract class MvpVmActivity<P extends BasePresenter, VW extends BaseViewWrapper, D extends ViewDataBinding>
extends BaseActivity<D> {
protected P presenter;
protected VW viewWrapper;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
presenter = createPresenter();
viewWrapper = createViewWrapper();
if (presenter != null && viewWrapper != null) {
presenter.setViewWrapper(viewWrapper);
}
}
protected abstract P createPresenter();
protected abstract VW createViewWrapper();
@Override
protected void onDestroy() {
if (presenter != null) {
presenter.detachView();
}
if (viewWrapper != null) {
viewWrapper.detachView();
}
if (dataBinding != null) {
dataBinding.unbind();
dataBinding = null;
}
super.onDestroy();
}
}
createPresenter和createViewWrapper由业务Activity继承实现，实例化对应业务的Presenter和ViewWrapper，后续博客会详细介绍。
MvpVmFragment
public abstract class MvpVmFragment<P extends BasePresenter, VW extends BaseViewWrapper, D extends ViewDataBinding>
extends BaseFragment<D> {
protected P presenter;
protected VW viewWrapper;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
presenter = createPresenter();
viewWrapper = createWrapper();
if (presenter != null && viewWrapper != null) {
presenter.setViewWrapper(viewWrapper);
}
}
protected abstract P createPresenter();
protected abstract VW createWrapper();
@Override
public void onDestroyView() {
if (presenter != null) {
presenter.detachView();
}
if (viewWrapper != null) {
viewWrapper.detachView();
}
if (dataBinding != null) {
dataBinding.unbind();
dataBinding = null;
}
super.onDestroyView();
}
}
createPresenter和createViewWrapper由业务Activity继承实现，实例化对应业务的Presenter和ViewWrapper，但是DataBinding实例的获取与在Activity中略有不同，是在onCreateView中获取的，后续博客会详细介绍。
DemoActivity
public class MvpVmDemoActivity extends MvpVmActivity<MvpVmDemoPresenter, MvpVmDemoViewWrapper, MvpVmDemoDataBinding>
implements MvpVmDemoContract.View {
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
dataBinding = generateDataBinding(R.layout.activity_mvpvm_demo);
if (viewWrapper != null) {
viewWrapper.setBinding(dataBinding);
}
presenter.fetchData();
}
@Override
protected MvpVmDemoPresenter createPresenter() {
return new MvpVmDemoPresenter(this);
}
@Override
protected MvpVmDemoViewWrapper createViewWrapper() {
return new MvpVmDemoViewWrapper(this);
}
...
}
从代码中可以看到，在onCreate第一步就是生成对应的DataBinding实例（关于DataBinding会在后续博客中专门讲一次），然后设置给ViewWrapper，实现数据绑定关系，在createPresenter和createViewWrapper中实例化对应业务的presenter和viewWrapper。
截至到此，MVPVM的Base框架就大体搭起来了，后续还会更新基于此框架的业务细节实现（Adapter、RecyclerView、DataBinding的高级用法以及网络请求框架Retrofit二次封装等）
才疏学浅，板砖轻拍
