Android MVP MVVM浅谈

• 关于MVC、MVP、MVVM认识及介绍，请详细阅读并深入了解
  https://juejin.im/entry/56ebb4ad5bbb50004c440972

• 关于MVC、MVP、MVVM的理解无外乎对数据的处理方式进一步的进行优化
  

• MVP P层实现Modle层获取数据，初始化Model，View层接口实现接口方法进行数据更新，数据加载，弹窗以及提示，而Activity仍然要实现View层接口在activity中对数据进行展示，相对于MVC而言是简化了很多，但是在Activity中仍然代码臃肿，需要处理很多数据展示等操作，下面是MVP P层以及Activity中代码。

• `public class MoviePresenter implements MovieContract.IMoviePresenter {
  MovieContract.IMovieModel mIMovieModel;//M层
  MovieContract.IMovieView mIMovieView;//V层
  public int start = 0;//从第几个开始
  public int count = 4;//请求多少个

`

  List<Movies.SubjectsBean> mMovies = new ArrayList<>();//请求到的电影信息对象集合

    public MoviePresenter(MovieContract.IMovieView mIMovieView) {
        this.mIMovieView = mIMovieView;
        mIMovieModel = new MovieModel();
    }

@Override
    public void getMovie() {
        mIMovieView.showProgress();//通知V层显示对话框
        //每次刷新加载4个
        mIMovieModel.getMovie(start, count, new OnHttpCallBack<Movies>() {//有一个请求结果的回调,即我调用请求电影信息的方法了,M层要返回一个成功还是失败的信息给我
            @Override
            public void onSuccessful(Movies movies) {//获取电影信息成功了,返回movies对象
                mIMovieView.hideProgress();//通知V层隐藏对话框
                mMovies.addAll(movies.getSubjects());//追加数据
                mIMovieView.showData(mMovies);//将获取到的信息显示到界面之前
                mIMovieView.showBottom(start - 5);//实现换页效果
            }

            @Override
            public void onFaild(String errorMsg) {
                mIMovieView.hideProgress();//通知V层隐藏对话框
                mIMovieView.showInfo(errorMsg);//通知V层显示错误信息
            }
        });
        start = start + 4;//改变请求的起点
    }

    /**
     * 加载更多
     */
    @Override
    public void loadMoreMovie() {
        getMovie();
    }

**Activity端代码**

public class MovieActivity extends BaseActivity implements MovieContract.IMovieView {
    MoviePresenter mMoviePresenter;
    private ProgressDialog mProgressDialog;
    @InjectView(R.id.rv_movie_list)
    RecyclerView rvMovieList;
    @InjectView(R.id.store_house_ptr_frame)
    PtrFrameLayout storeHousePtrFrame;
    private TextView load_more;//加载更多的按钮

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        initView();
        mMoviePresenter = new MoviePresenter(this);
        mMoviePresenter.getMovie();//启动软件时默认加载
    }

    @Override
    protected void $setToolBar() {
        super.$setToolBar();
        setTitle("豆瓣Top250的电影");
        setLeftImage(R.drawable.back);
        setRightTitle("电影");
    }

    /**
     * 初始化布局
     */
    private void initView() {
        setContentView(R.layout.content_movie);
        ButterKnife.inject(this);
        $setToolBar();
        initPtr();
        rvMovieList.setLayoutManager(new LinearLayoutManager(mActivity));//设置为listview的布局
        rvMovieList.setItemAnimator(new DefaultItemAnimator());//设置动画
        rvMovieList.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST));//添加分割线
    }

    /**
     * 初始化(配置)下拉刷新组件
     */
    private void initPtr() {
        //下面是一些基础的配置,直接拿来用就可以 不用深究
        storeHousePtrFrame.setResistance(1.7f);
        storeHousePtrFrame.setRatioOfHeaderHeightToRefresh(1.2f);
        storeHousePtrFrame.setDurationToClose(200);
        storeHousePtrFrame.setDurationToCloseHeader(1000);
        storeHousePtrFrame.setPullToRefresh(false);
        storeHousePtrFrame.setKeepHeaderWhenRefresh(true);
        StoreHouseHeader header = new StoreHouseHeader(this);
        float scale = getResources().getDisplayMetrics().density;
        header.setPadding(0, (int) (15 * scale + 0.5f), 0, (int) (15 * scale + 0.5f));
        header.initWithString("GY");//自定义头显示的字样,设置图片的话看另外的api
//      header.invalidateDrawable();
        header.setTextColor(Color.RED);
        header.setBackgroundColor(Color.parseColor("#11000000"));
        storeHousePtrFrame.setHeaderView(header);//添加头
        storeHousePtrFrame.addPtrUIHandler(header);//同时也要加上这一句
        storeHousePtrFrame.setPtrHandler(new PtrHandler() {
            @Override
            public boolean checkCanDoRefresh(PtrFrameLayout frame, View content, View header) {
                return PtrDefaultHandler.checkContentCanBePulledDown(frame, content, header);
            }

            @Override
            public void onRefreshBegin(PtrFrameLayout frame) {
                mMoviePresenter.loadMoreMovie();//下拉刷新的时候加载更多数据
                frame.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        storeHousePtrFrame.refreshComplete();
                    }
                }, 150);//为了增加用户体验 延迟0.15s再通知刷新结束
            }
        });

    }

    @Override
    public void showBottom(int lastIndex) {
        load_more.setText("点击加载更多");//设置最底下的加载更多显示的内容    加载中-->点击加载更多
        rvMovieList.scrollToPosition(lastIndex);
    }

    @Override
    public Context getCurContext() {
        return this;
    }

    @Override
    public void showProgress() {
        mProgressDialog = ProgressDialog.show(this, "提示", "正在获取中,请稍后...");
    }

    @Override
    public void hideProgress() {
        mProgressDialog.hide();
    }


    /**
     * 显示数据
     *
     * @param movies
     */
    @Override
    public void showData(List<Movies.SubjectsBean> movies) {
        //鸿洋大神的通用适配器(真的很好用哦)
        CommonAdapter<Movies.SubjectsBean> commonAdapter = new CommonAdapter<Movies.SubjectsBean>(this, R.layout.movie_item, movies) {

            @Override
            protected void convert(ViewHolder holder, Movies.SubjectsBean subjectsBean, int position) {
                String title = (position + 1) + "、" + subjectsBean.getTitle() + "/" + subjectsBean.getOriginal_title();
                holder.setText(R.id.tv_movie_title, title);//设置电影名
                String doc = "";
                for (Movies.SubjectsBean.DirectorsBean directorsBean : subjectsBean.getDirectors()) {
                    doc += directorsBean.getName() + "  ";
                }
                holder.setText(R.id.tv_movie_doc, "导演:" + doc);
                String casts = "";
                for (Movies.SubjectsBean.CastsBean castsBean : subjectsBean.getCasts()) {
                    casts += castsBean.getName() + "  ";
                }

                holder.setText(R.id.tv_movie_art, "主演:" + casts);
                String genres = "";
                for (String genre : subjectsBean.getGenres()) {
                    genres += genre + " ";
                }
                holder.setText(R.id.tv_movie_type, subjectsBean.getYear() + " / " + genres);//年份+分级
                holder.setText(R.id.tv_movie_grade, subjectsBean.getRating().getAverage() + "");//评分
                ImageView iv_pic = holder.getView(R.id.iv_movie_pic);
                Glide.with(mActivity)
                        .load(subjectsBean.getImages().getSmall())
                        .diskCacheStrategy(DiskCacheStrategy.ALL)//加快显示速度---缓存在本地磁盘
                        .into(iv_pic);//图片
            }
        };
        /**
         * 配置加载更多(通用适配器里面的类哦)
         */
        LoadMoreWrapper mLoadMoreWrapper = new LoadMoreWrapper(commonAdapter);//加载更多的包装器(传入通用适配器)
        View view = View.inflate(mActivity, R.layout.load_more, null);
        //要设置一下的布局参数,因为布局填充到包装器的时候,自己的一些属性会无效
        LinearLayout.LayoutParams mLayoutParams = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        view.setLayoutParams(mLayoutParams);
        load_more = (TextView) view.findViewById(R.id.tv_load_more);

        //监听点击加载更多事件
        load_more.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                load_more.setText("加载中...");//点击加载更多-->加载中
                mMoviePresenter.loadMoreMovie();
            }
        });
        mLoadMoreWrapper.setLoadMoreView(view);
        rvMovieList.setAdapter(mLoadMoreWrapper);//注意  这里添加的是包装器 不是适配器哦
    }

    @Override
    public void showInfo(String info) {
        ToastUtils.showToast(this, info);
    }

• MVVM VM层实现数据请求监听器，初始化Modle实现类，调用获取数据的方法拿到数据，在成功失败的回调方法里面对数据进行提示，刷新，加载，对UI进行数据展示，前提是你引入DataBinding引入布局，不知道的可以先去查一下MVVM引入DataBinding如何进行实现的。下面是VM以及activity代码。
• public class MovieListVm implements OnHttpCallBack<Movies>{
public int start = 0;//从第几个开始
public int count = 4;//请求多少个
MovieModleBiz movieModleBiz;


 private TextView load_more;//加载更多的按钮
    List<Movies.SubjectsBean> mMovies = new ArrayList<>();//请求到的电影信息对象集合
    private ActivityMovieBinding binding;
    private Context context;
    MovieAdapter movieAdapter;
    private MovieListVm movieListVm;
    private ProgressDialog mProgressDialog;
    public MovieListVm(Context context,ActivityMovieBinding binding){
        this.binding=binding;
        this.context=context;
        init();
    }
    /**
     * 初始化
     */
    private void init() {
        movieModleBiz = new MovieModleBiz();
        firstLoadData();
    }

    /**
     * 首次加载
     */
    public void firstLoadData() {
         showProgress();//通知V层显示对话框
          movieModleBiz.getMovie(start, count,this);
          start = start + 4;//改变请求的起点
    }



    @Override
    public void onSuccessful(Movies movies) {


        hideProgress();//通知V层隐藏对话框
        mMovies.addAll(movies.getSubjects());//追加数据
        movieAdapter=new MovieAdapter(context,R.layout.movie_item,mMovies);
       showData(mMovies);//将获取到的信息显示到界面之前
       showBottom(start - 5);//实现换页效果
    }

    @Override
    public void onFaild(String errorMsg) {
        hideProgress();//通知V层隐藏对话框
        showInfo(errorMsg);//通知V层显示错误信息
    }

   public void showBottom(int lastIndex){
       binding.rvMovieList.scrollToPosition(lastIndex);
   };

    public void showProgress(){
        mProgressDialog = ProgressDialog.show(context, "提示", "正在获取中,请稍后...");
    };//显示进度条

    public void hideProgress(){

            mProgressDialog.hide();
    };//隐藏进度条

    public  void showData(List<Movies.SubjectsBean> movies){
        LoadMoreWrapper mLoadMoreWrapper = new LoadMoreWrapper(movieAdapter);//加载更多的包装器(传入通用适配器)
        View view = View.inflate(context, R.layout.load_more, null);
        //要设置一下的布局参数,因为布局填充到包装器的时候,自己的一些属性会无效
        LinearLayout.LayoutParams mLayoutParams = new LinearLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT);
        view.setLayoutParams(mLayoutParams);
        load_more = (TextView) view.findViewById(R.id.tv_load_more);

        //监听点击加载更多事件
        load_more.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                load_more.setText("加载中...");//点击加载更多-->加载中
                firstLoadData();
            }
        });
        mLoadMoreWrapper.setLoadMoreView(view);
       binding. rvMovieList.setAdapter(mLoadMoreWrapper);//注意  这里添加的是包装器 不是适配器哦
    };//显示数据到View上

    public void showInfo(String info){
        ToastUtils.showToast(context, info);
    };//提示用户,提升友好交互
}

**Acitivity代码**
public class MvvmMoviActivity extends BaseMvVmActivity<ActivityMovieBinding>{

    RecyclerView rvMovieList;
    PtrFrameLayout storeHousePtrFrame;
    private MovieListVm moviewListVm;
    @Override
    public int getLayoutId() {
        return R.layout.activity_movie;
    }

    @Override
    public void init(Bundle savedInstanceState) {
        initView();
        initVm();
    }

    private void initVm() {
      moviewListVm= new MovieListVm(this, viewDataBinding);
    }

    private void initView() {
        rvMovieList=viewDataBinding.rvMovieList;
        storeHousePtrFrame=viewDataBinding.storeHousePtrFrame;
        initPtr();
        rvMovieList.setLayoutManager(new LinearLayoutManager(this));//设置为listview的布局
        rvMovieList.setItemAnimator(new DefaultItemAnimator());//设置动画
        rvMovieList.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST));//添加分割线
    }

    /**
     * 初始化(配置)下拉刷新组件
     */
    private void initPtr() {
        //下面是一些基础的配置,直接拿来用就可以 不用深究
        storeHousePtrFrame.setResistance(1.7f);
        storeHousePtrFrame.setRatioOfHeaderHeightToRefresh(1.2f);
        storeHousePtrFrame.setDurationToClose(200);
        storeHousePtrFrame.setDurationToCloseHeader(1000);
        storeHousePtrFrame.setPullToRefresh(false);
        storeHousePtrFrame.setKeepHeaderWhenRefresh(true);
        StoreHouseHeader header = new StoreHouseHeader(this);
        float scale = getResources().getDisplayMetrics().density;
        header.setPadding(0, (int) (15 * scale + 0.5f), 0, (int) (15 * scale + 0.5f));
        header.initWithString("GY");//自定义头显示的字样,设置图片的话看另外的api
//      header.invalidateDrawable();
        header.setTextColor(Color.RED);
        header.setBackgroundColor(Color.parseColor("#11000000"));
        storeHousePtrFrame.setHeaderView(header);//添加头
        storeHousePtrFrame.addPtrUIHandler(header);//同时也要加上这一句
        storeHousePtrFrame.setPtrHandler(new PtrHandler() {
            @Override
            public boolean checkCanDoRefresh(PtrFrameLayout frame, View content, View header) {
                return PtrDefaultHandler.checkContentCanBePulledDown(frame, content, header);
            }

            @Override
            public void onRefreshBegin(PtrFrameLayout frame) {
               //下拉刷新的时候加载更多数据
                moviewListVm.firstLoadData();
                frame.postDelayed(new Runnable() {
                    @Override
                    public void run() {
                        storeHousePtrFrame.refreshComplete();
                    }
                }, 150);//为了增加用户体验 延迟0.15s再通知刷新结束
            }
        });

    }



}

• 下面是在github上的源码，在了解了MVP和MVVM之后可以下载源码进行验证实现。
• github链接