Android

Android学习笔记---MVP架构系列0x03

上次我们完成了界面的展现,这次我们把数据绑定到界面上,然后把整个项目都完善好.想查看完整的代码可以到这里

代码

MovieContract.java

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/**
 * 用于管理loadMovie功能模块的View与Presenter
 */
public class MovieContract {
    /**
     * loadMovie模块的View,提供对外的UI更新接口
     */
    interface View extends BaseView<Presenter>{
        void loadMore(ArrayList<Movie> movie);//上拉加载更多
        void refresh(ArrayList<Movie> movie);//下拉刷新
        void loadCompleted();//改变上拉加载状态
    }
    /**
     * loadMovie模块的Presenter,负责获取数据并处理,更新UI
     */
    interface Presenter extends BasePresenter{
        void refresh();//刷新
        void loadMore(int start);//加载更多
    }
}

现在我们需要定义项目的数据对象,按照HTTP返回的JSON数据,我们定义了下面3个数据对象

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/**
 * 电影图片对象
 */
public class MovieImage{
    String small;
    String large;
    String medium;
    public String getSmall() {
        return small;
    }
    public void setSmall(String small) {
        this.small = small;
    }
    public String getLarge() {
        return large;
    }
    public void setLarge(String large) {
        this.large = large;
    }
    public String getMedium() {
        return medium;
    }
    public void setMedium(String medium) {
        this.medium = medium;
    }
}

/**
 * 一个电影对象,包含标题和图片URL
 */
public class Movie {
    String title;
    MovieImage images;
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public MovieImage getImages() {
        return images;
    }
    public void setImages(MovieImage images) {
        this.images = images;
    }
}

/**
 * 网络请求返回的Json数据
 */
public class HttpResult {
    ArrayList<Movie> subjects;
    public ArrayList<Movie> getSubjects() {
        return subjects;
    }
    public void setSubjects(ArrayList<Movie> subjects) {
        this.subjects = subjects;
    }
}

接下来我们就可以完成数据请求和展现了,首先我们先完成数据的获取,按照Retrofit的请求方法完成数据的请求.
MovieService.java

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public interface MovieService {
    @GET("top250")
    Call<HttpResult> getMovie(@Query("start") int start,@Query("count") int count);
}

MoviePresenter.java

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/**
 * 具体的loadMovie模块的Presenter
 */
public class MoviePresenter implements MovieContract.Presenter {
    //持有View对象,用于对UI进行更新
    MovieContract.View mView;
    String BASIC_URL = "https://api.douban.com/v2/movie/";

    public MoviePresenter(MovieContract.View view) {
        this.mView = view;
        mView.setPresenter(this);
    }

    @Override
    public void start() {
    }
    @Override
    public void refresh() {
        MovieService service = getMovieService();
        Call<HttpResult> call = service.getMovie(0, 25);
        call.enqueue(new Callback<HttpResult>() {
            @Override
            public void onResponse(Call<HttpResult> call, Response<HttpResult> response) {
                ArrayList<Movie> subjects = response.body().getSubjects();
                mView.refresh(subjects);//更新UI
            }
            @Override
            public void onFailure(Call<HttpResult> call, Throwable t) {
            }
        });
    }

    /**
     * 获取MovieService
     * @return
     */
    private MovieService getMovieService() {
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl(BASIC_URL)
                .addConverterFactory(GsonConverterFactory.create())
                .build();
        return retrofit.create(MovieService.class);
    }
    @Override
    public void loadMore(int start) {
        Log.e("start", start + "");
        MovieService service = getMovieService();
        Call<HttpResult> call = service.getMovie(start, 25);
        call.enqueue(new Callback<HttpResult>() {
            @Override
            public void onResponse(Call<HttpResult> call, Response<HttpResult> response) {
                ArrayList<Movie> subjects = response.body().getSubjects();
                if (subjects != null) {
                    mView.loadMore(subjects);//更新UI
                    mView.loadCompleted();//改变加载状态
                }
            }
            @Override
            public void onFailure(Call<HttpResult> call, Throwable t) {
            }
        });
    }
}

最后只要完成界面的显示处理即可
MovieFragment.java

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public class MovieFragment extends Fragment implements MovieContract.View {

    //持有Presenter的实例
    MoviePresenter mPresenter;
    ArrayList<Movie> movies = new ArrayList<>();
    MovieAdapter mAdapter;
    @BindView(R.id.mf_rv_list)
    RecyclerView rv_list;
    @BindView(R.id.mf_srl)
    SwipeRefreshLayout srl;
    @BindView(R.id.load_more)
    LinearLayout load_more;
    private boolean isLoading=false;

    public static MovieFragment newInstance() {
        return new MovieFragment();
    }

    public MovieFragment() {

    }

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View root = inflater.inflate(R.layout.movie_frag, container, false);
        ButterKnife.bind(this, root);
        mAdapter = new MovieAdapter(getActivity(), movies);
        initView();
        return root;
    }
    
    private void initView() {
        load_more.setVisibility(View.GONE);
        srl.setColorSchemeColors(R.color.colorPrimary);
        srl.post(new Runnable() {
            @Override
            public void run() {
                srl.setRefreshing(true);
            }
        });
        srl.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                mPresenter.refresh();
            }
        });
        mPresenter.refresh();
        final StaggeredGridLayoutManager layoutManager = new StaggeredGridLayoutManager(3, StaggeredGridLayoutManager.VERTICAL);
        rv_list.setLayoutManager(layoutManager);
        rv_list.setAdapter(mAdapter);
        rv_list.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
                int lastPositions[] = layoutManager.findLastVisibleItemPositions(new int[layoutManager.getSpanCount()]);
                int lastVisiableItemPos = findMax(lastPositions);
                if (lastVisiableItemPos == mAdapter.getItemCount()-1) {
                    if(!isLoading) {
                        isLoading=true;
                        load_more.setVisibility(View.VISIBLE);
                        mPresenter.loadMore(lastVisiableItemPos + 1);
                    }
                }
            }

            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);
            }
        });
    }

    private int findMax(int[] lastPositions) {
        int max = lastPositions[0];
        for (int value : lastPositions) {
            if (value > max) {
                max = value;
            }
        }
        return max;
    }

    @Override
    public void setPresenter(MovieContract.Presenter presenter) {
        mPresenter = (MoviePresenter) presenter;
    }

    @Override
    public void loadMore(ArrayList<Movie> movie) {
        movies.addAll(movie);
        mAdapter.notifyDataSetChanged();
        load_more.setVisibility(View.GONE);
    }

    @Override
    public void refresh(ArrayList<Movie> movie) {
        movies.clear();
        movies.addAll(movie);
        mAdapter.notifyDataSetChanged();
        srl.setRefreshing(false);
    }
    @Override
    public void loadCompleted() {
        isLoading = false;
    }
}

最后我们把其余部分的代码完善便可
MovieAdapter.java

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/**
 * Movie列表的Adapter
 */
public class MovieAdapter extends RecyclerView.Adapter<MovieVH> {

    Context mContext;
    private ArrayList<Movie> movies;

    public MovieAdapter(Context context, ArrayList<Movie> movies) {
        this.mContext = context;
        this.movies = movies;
    }

    @Override
    public MovieVH onCreateViewHolder(ViewGroup parent, int viewType) {
        return new MovieVH(LayoutInflater.from(mContext).inflate(R.layout.item_movie, null));
    }

    @Override
    public void onBindViewHolder(MovieVH holder, int position) {
        String url = movies.get(position).getImages().getMedium();
        Glide.with(mContext).load(url).placeholder(R.drawable.pictures_no).centerCrop().into(holder.iv_movie);
        holder.tv_title.setText(movies.get(position).getTitle());

    }

    @Override
    public int getItemCount() {
        return movies == null ? 0 : movies.size();
    }

}

class MovieVH extends RecyclerView.ViewHolder {
    @BindView(R.id.im_iv_movie)
    ImageView iv_movie;
    @BindView(R.id.im_tv_title)
    TextView tv_title;

    public MovieVH(View itemView) {
        super(itemView);
        ButterKnife.bind(this, itemView);
    }
}

完整的代码可以到我的Github上查看.

效果

最后我们的效果图如下
豆瓣电影Top250

总结

通过本次的一个简单的项目,介绍了MVP架构在Android上该如何实现.希望能对大家起到帮助.