RecyclerView + DataBinding实现的下拉刷

作者: 云烟渐成雨 | 来源:发表于2019-07-23 22:49 被阅读61次

RecyclerView + DataBinding实现的下拉刷
Android面试整理
viewWapper的步骤
SelectAdapter（图片选择）
借助 android databinding 框架，逃离 ada
RecyclerView的刷新和加载更多--个人笔记
可实现头部图片下拉放大RecyclerView
RecyclerViewRefresh
安卓RecyclerView那些事-（二）实现一个下拉刷新、划到
Recyclerview的使用（三）：SwipeRefreshL

1、简介

RecyclerView的刷新与加载样式用到第三方库，添加依赖：

implementation 'com.jcodecraeer:xrecyclerview:1.5.9'

在使用RecyclerView来展示网络请求的数据的时候，常用到下拉刷新和加载更多，直接上效果图:

screen.gif

项目中使用的接口来源:http://gank.io/api
以下介绍并非图中体现的完整实现，部分Activity与Fragment等代码未贴出
项目源码地址：https://github.com/fr1014/konwledge

2、布局

2.1 gson数据解析

public class CategoryListBean {

    private boolean error;
    private List<ResultsBean> results;

    public boolean isError() {
        return error;
    }

    public void setError(boolean error) {
        this.error = error;
    }

    public List<ResultsBean> getResults() {
        return results;
    }

    public void setResults(List<ResultsBean> results) {
        this.results = results;
    }

    public static class ResultsBean {

        private String _id;
        private String createdAt;
        private String desc;
        private String publishedAt;
        private String source;
        private String type;
        private String url;
        private boolean used;
        private String who;
        private List<String> images;

        public String get_id() {
            return _id;
        }

        public void set_id(String _id) {
            this._id = _id;
        }

        public String getCreatedAt() {
            return createdAt;
        }

        public void setCreatedAt(String createdAt) {
            this.createdAt = createdAt;
        }

        public String getDesc() {
            return desc;
        }

        public void setDesc(String desc) {
            this.desc = desc;
        }

        public String getPublishedAt() {
            return publishedAt;
        }

        public void setPublishedAt(String publishedAt) {
            this.publishedAt = publishedAt;
        }

        public String getSource() {
            return source;
        }

        public void setSource(String source) {
            this.source = source;
        }

        public String getType() {
            return type;
        }

        public void setType(String type) {
            this.type = type;
        }

        public String getUrl() {
            return url;
        }

        public void setUrl(String url) {
            this.url = url;
        }

        public boolean isUsed() {
            return used;
        }

        public void setUsed(boolean used) {
            this.used = used;
        }

        public String getWho() {
            return who;
        }

        public void setWho(String who) {
            this.who = who;
        }

        public List<String> getImages() {
            return images;
        }

        public void setImages(List<String> images) {
            this.images = images;
        }
    }
}

2.2 数据源处理

public class CategoryBean extends BaseObservable {
    private ResultsBean bean;
    public ObservableField<Integer> imageViewVisibility;
    private int mPosition;

    public CategoryBean(ResultsBean bean, int position) {
        this.bean = bean;
        this.mPosition = position;
        initData();

    }

    public String getDesc() {
        return bean.getDesc();
    }

    public List<String> getImageUrls() {
        return bean.getImages();
    }

    public String getImageUrl() {
        if (bean.getImages()!=null)
            return bean.getImages().get(0);
        else
            imageViewVisibility.set(View.GONE);
        return null;
    }

    public Date getDate(){
        return Utils.StrToDate(bean.getPublishedAt());
    }

    public String getUrl(){
        return bean.getUrl();
    }

    public String getType(){
        return bean.getType();
    }

    private void initData() {
        imageViewVisibility = new ObservableField<>();
        imageViewVisibility.set(View.VISIBLE);
    }
}

2.3 RecyclerView的布局

fragment_classified_child.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent">

            <com.jcodecraeer.xrecyclerview.XRecyclerView
                android:id="@+id/recycler_view"
                android:layout_width="match_parent"
                android:layout_height="match_parent"/>
    </RelativeLayout>

</layout>

2.4 RecyclerView中的item布局

item_categorybean.xml

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <data>

        <variable
            name="categorybean"
            type="com.fr.konwledge.bean.CategoryBean" />

        <variable
            name="date"
            type="java.util.Date" />
    </data>

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="95dp">

        <RelativeLayout
            android:id="@+id/list_item"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="?attr/selectableItemBackground"
            android:padding="8dp">

            <TextView
                android:id="@+id/desc"
                android:layout_toStartOf="@id/image_view"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_alignParentStart="true"
                android:ellipsize="end"
                android:maxLines="3"
                android:text="@{categorybean.desc}"
                android:textColor="@color/text_color" />

            <TextView
                android:id="@+id/type"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentBottom="true"
                android:text="@{categorybean.type}"
                android:textColor="@color/text_color" />

            <TextView
                android:id="@+id/date"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentBottom="true"
                android:layout_marginLeft="80dp"
                android:layout_toEndOf="@id/type"
                android:text="@{categorybean.date}"
                android:textColor="@color/text_color" />

            <ImageView
            android:id="@+id/image_view"
            android:layout_width="60dp"
            android:layout_height="wrap_content"
            android:layout_alignParentEnd="true"
            android:layout_centerVertical="true"
            android:layout_margin="4dp"
            android:visibility="@{categorybean.imageViewVisibility}"
            android:src="@drawable/ic_launcher_background"
            app:imageUrl="@{categorybean.imageUrl}" />
        </RelativeLayout>

        <View
            android:layout_width="match_parent"
            android:layout_height="1dp"
            android:layout_alignParentBottom="true"
            android:background="@color/black_view" />
    </RelativeLayout>
</layout>

3、接口实现

3.1 监听网络请求

在请求网络时，负责将各种状态下的信息传出

public interface BaseLoadListener<T> {

    /**
     * 加载数据成功
     *
     * @param list
     */
    void loadSuccess(List<T> list);

    /**
     * 加载失败
     *
     * @param message
     */
    void loadFailure(String message);

    /**
     * 开始加载
     */
    void loadStart();

    /**
     * 加载结束
     */
    void loadComplete();
}

3.2 UI消息展示

负责将加载状态展示给用户

public interface IBaseView {

    /**
     * 开始加载
     *
     * @param loadType 加载的类型 0：第一次记载 1：下拉刷新 2：上拉加载更多
     */
    void loadStart(int loadType);

    /**
     * 加载完成
     */
    void loadComplete();

    /**
     * 加载失败
     *
     * @param message
     */
    void loadFailure(String message);
}

4、适配器

4.1 适配器的基类实现

RecyclerView的ViewHolder基类

public class BaseViewHolder<VB extends ViewDataBinding> extends RecyclerView.ViewHolder {

    private VB mBinding;

    public BaseViewHolder(VB binding) {
        super(binding.getRoot());
        this.mBinding = binding;
    }

    public VB getBinding(){
        return mBinding;
    }
}

RecyclerView适配器的通用基类

public abstract class RVBaseAdapter<T, VH extends RecyclerView.ViewHolder> extends RecyclerView.Adapter<VH> {

    protected Context mContext;
    protected List<T> mList; // 数据源
    protected LayoutInflater inflater;

    public RVBaseAdapter(Context context) {
        this.mContext = context;
        this.mList = new ArrayList<>();
        inflater = LayoutInflater.from(context);
    }

    @Override
    public int getItemCount() {
        return mList.size();
    }

    @NotNull
    @Override
    public VH onCreateViewHolder(@NotNull ViewGroup parent, int viewType) {
        return onCreateVH(parent, viewType);
    }

    @Override
    public void onBindViewHolder(@NotNull VH holder, int position) {
        onBindVH(holder, position);
    }

    /**
     * 创建 View Holder
     *
     * @param parent   parent
     * @param viewType item type
     * @return view holder
     */
    public abstract VH onCreateVH(ViewGroup parent, int viewType);

    /**
     * 绑定 View Holder
     *
     * @param holder   view holder
     * @param position position
     */
    public abstract void onBindVH(VH holder, int position);

    /**
     * 刷新数据
     *
     * @param data 数据源
     */
    public void refreshData(List<T> data) {
        mList.clear();
        mList.addAll(data);
        notifyDataSetChanged();
    }

    /**
     * 加载更多
     *
     * @param data 加载的新数据
     */
    public void loadMoreData(List<T> data) {
        mList.addAll(data);
        notifyDataSetChanged();
    }

}

4.2 适配器的实现

RecyclerView的适配器

public class RVCategoryAdapter extends RVBaseAdapter<ResultsBean,BaseViewHolder<ItemCategorybeanBinding>> {

    public RVCategoryAdapter(Context context) {
        super(context);
    }

    @Override
    public BaseViewHolder<ItemCategorybeanBinding> onCreateVH(ViewGroup parent, int viewType) {
        ViewDataBinding dataBinding = DataBindingUtil.inflate(inflater, R.layout.item_categorybean,parent,false);
        return new BaseViewHolder<>((ItemCategorybeanBinding) dataBinding);
    }

    @Override
    public void onBindVH(BaseViewHolder<ItemCategorybeanBinding> holder, int position) {
        ItemCategorybeanBinding binding = holder.getBinding();
        CategoryBean bean = new CategoryBean(mList.get(position), position);
        binding.setVariable(BR.categorybean,bean);
        binding.executePendingBindings();
    }

}

5、model类

网络请求的部分封装这里就不详写了，文末有项目源码地址，仅供参考。

//获取分类干货
@GET("data/{category}/{count}/{page}")
Observable<Response<CategoryListBean>> getCategoryBean(@Path("category")String category, @Path("count") int count, @Path("page") int page);

public class CategoryModel {

    public static void getCategoryListBean(String category, int count, int page, BaseLoadListener<ResultsBean> loadListener) {
        RetrofitManager
                .getRequest()
                .getCategoryBean(category, count, page)
                .compose(SchedulerProvider.getInstance().applySchedulers())
                .subscribe(new DisposableObserver<Response<CategoryListBean>>() {

                    @Override
                    protected void onStart() {
                        loadListener.loadStart();
                    }

                    @Override
                    public void onNext(Response<CategoryListBean> categoryListBeanResponse) {
                        if (categoryListBeanResponse != null && !categoryListBeanResponse.body().isError()){
                            loadListener.loadSuccess(categoryListBeanResponse.body().getResults());
                        }
                    }

                    @Override
                    public void onError(Throwable e) {
                        loadListener.loadFailure(e.getMessage());
                    }

                    @Override
                    public void onComplete() {
                        loadListener.loadComplete();
                    }
                });
    }
}

5、ViewModel类

5.1 常量

public class MainConstant {

    public class LoadData{
        public static final int FIRST_LOAD = 0; //首次加载
        public static final int REFRESH = 1; //下拉刷新
        public static final int LOAD_MORE = 2; //上拉加载更多
    }
}

5.2 ViewModel基类

public abstract class BaseViewModel<T> {
    protected T adapter;

    public BaseViewModel(T adapter){
        this.adapter = adapter;
    }

    protected abstract void getData();

}

5.3 ViewModel的实现

继承实现网络请求监听接口，判断UI的不同状态，做出第一次进入界面、刷新数据、加载更多的不同操作。

public class CategoryViewModel extends BaseViewModel<RVCategoryAdapter> implements BaseLoadListener<ResultsBean> {

    private ICategoryView mICategoryView;
    private String mCategory;
    private int mCurrPage = 1; //当前页面
    private int mLoadType; //加载数据的类型

    public CategoryViewModel(ICategoryView iCategoryView,RVCategoryAdapter adapter,String category) {
        super(adapter);
        this.mICategoryView = iCategoryView;
        this.mCategory = category;
        getData();
    }

    /**
     * 第一次获取分类数据
     */
    @Override
    protected void getData() {
        mLoadType = MainConstant.LoadData.FIRST_LOAD;
        CategoryModel.getCategoryListBean(mCategory,10,mCurrPage,this);
    }


    public void loadRefreshData(){
        mLoadType = MainConstant.LoadData.REFRESH;
        mCurrPage = 1;
        CategoryModel.getCategoryListBean(mCategory,30,mCurrPage,this);
    }

    public void loadMoreData(){
        mLoadType = MainConstant.LoadData.LOAD_MORE;
        mCurrPage++;
        CategoryModel.getCategoryListBean(mCategory,30,mCurrPage,this);
    }

    @Override
    public void loadSuccess(List<ResultsBean> list) {
        if (mCurrPage > 1){
            //上拉加载的数据
            adapter.loadMoreData(list);
        }else {
            //第一次加载或者下拉刷新的数据
            adapter.refreshData(list);
        }
    }

    @Override
    public void loadFailure(String message) {
        //加载失败后的提示
        if (mCurrPage > 1){
            //加载失败需要回到加载前的页面
            mCurrPage--;
        }
        mICategoryView.loadFailure(message);
    }

    @Override
    public void loadStart() {
        mICategoryView.loadStart(mLoadType);
    }

    @Override
    public void loadComplete() {
        mICategoryView.loadComplete();
    }
}

6、Fragment

6.1 Fragment基类

public abstract class BaseFragment<V extends ViewDataBinding> extends Fragment {
    protected V binding;
    
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        binding = DataBindingUtil.inflate(inflater, initContentView(inflater, container, savedInstanceState), container, false);
        return binding.getRoot();
    }

    @Override
    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        initViewDataBinding();
        //页面数据初始化方法
        initData();
    }

    public abstract void initData();

    private void initViewDataBinding() {

    }

    public abstract int initContentView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState);
    
}

6.2、Fragment的实现

这里的仅为ClassifiedChildFragment的代码，Activity及ClassifiedChildFragment的父布局Fragment都未贴出。

public class ClassifiedChildFragment extends BaseFragmentVM<FragmentClassifiedChildBinding,CategoryViewModel> implements ICategoryView, XRecyclerView.LoadingListener{
    private String mClassified;

    public ClassifiedChildFragment(String classified){
        this.mClassified = classified;
    }

    @Override
    public int initContentView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        return R.layout.fragment_classified_child;
    }

    @Override
    public void initData() {
        binding.recyclerView.setRefreshProgressStyle(ProgressStyle.BallClipRotate); //设置下拉刷新的样式
        binding.recyclerView.setLoadingMoreProgressStyle(ProgressStyle.BallClipRotate); //设置上拉加载更多的样式
        binding.recyclerView.setArrowImageView(R.mipmap.pull_down_arrow);
        binding.recyclerView.setLoadingListener(this);

        LinearLayoutManager layoutManager = new LinearLayoutManager(getContext());
        binding.recyclerView.setLayoutManager(layoutManager);

        RVCategoryAdapter mRVCategoryAdapter = new RVCategoryAdapter(getContext());
        binding.recyclerView.setAdapter(mRVCategoryAdapter);
        viewModel = new CategoryViewModel(this, mRVCategoryAdapter, mClassified);
    }

    @Override
    public void onRefresh() {
        //下拉刷新
        viewModel.loadRefreshData();
    }

    @Override
    public void onLoadMore() {
        //上拉加载更多
        viewModel.loadMoreData();
    }

    @Override
    public void loadStart(int loadType) {
        if (loadType == FIRST_LOAD) {
            DialogHelper.getInstance().show(getContext(), "加载中...");
        }
    }

    @Override
    public void loadComplete() {
        DialogHelper.getInstance().close();
        binding.recyclerView.refreshComplete();
        binding.recyclerView.loadMoreComplete();
    }

    @Override
    public void loadFailure(String message) {
        DialogHelper.getInstance().close();
        binding.recyclerView.loadMoreComplete();
        binding.recyclerView.refreshComplete();
        Utils.ToastShort(getContext(), message);
    }

}

6.3 DialogHelper

public class DialogHelper {
    public static DialogHelper getInstance() {
        return LoadDialogHolder.instance;
    }

    private static class LoadDialogHolder {
        static DialogHelper instance = new DialogHelper();
    }

    /**
     * 展示加载框
     *
     * @param context context
     * @param msg     加载信息
     */
    public void show(Context context, String msg) {
        close();
        createDialog(context, msg);
        if (progressDialog != null && !progressDialog.isShowing()) {
            progressDialog.show();
        }
    }

    /**
     * 关闭加载框
     */
    public void close() {
        if (progressDialog != null && progressDialog.isShowing()) {
            progressDialog.dismiss();
        }
    }

    /**
     * progressDialog
     */
    private ProgressDialog progressDialog;

    /**
     * 创建加载框
     *
     * @param context context
     * @param msg     msg
     */
    private void createDialog(Context context, String msg) {
        progressDialog = new ProgressDialog(context);
        progressDialog.setCancelable(false);
        progressDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
        progressDialog.setMessage(msg);
        progressDialog.setOnCancelListener(dialog -> progressDialog = null);
    }
}

7、项目源码地址

https://github.com/fr1014/konwledge

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RecyclerView + DataBinding实现的下拉刷

1、简介

2、布局

2.1 gson数据解析

2.2 数据源处理

2.3 RecyclerView的布局

2.4 RecyclerView中的item布局

3、接口实现

3.1 监听网络请求

3.2 UI消息展示

4、适配器

4.1 适配器的基类实现

4.2 适配器的实现

5、model类

5、ViewModel类

5.1 常量

5.2 ViewModel基类

5.3 ViewModel的实现

6、Fragment

6.1 Fragment基类

6.2、Fragment的实现

6.3 DialogHelper

7、项目源码地址

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