RecycleView 滑動到底部，加載更多，recycleview滑動

RecycleView 滑動到底部，加載更多，recycleview滑動

　　android.support.v7 包提供了一個新的組件：RecycleView，用以提供一個靈活的列表試圖、顯示大型數據集，它支持局部刷新、顯示動畫等功能，可以用來取代ListView與GridView.

　　然而在使用的過程中卻遇到一些問題，基本現在手機頁面都會有滑動到底部加載更多的功能，而RecycleView 並沒有提供像ListView的addFooter等方法，所以實現起來還是有點麻煩。經過一段時間的摸索，終於找到實現RecycleView加載更多的方法。

　　本文主要通過RecycleView 的 ItemViewType 來實現RecycleView活動到底部加載更多功能，支持 列表、網格、瀑布流等布局。

　　根據ItemViewType創建兩種布局，一個用於顯示正常內容的布局，一個用於加載布局，然後監聽RecycleView的滾動事件，當滑動到底部時添加加載布局，對於列表布局來說很簡單，不再熬述，然而對於網格布局與瀑布流布局來說，要解決"加載布局只占用一列"的問題,

　　1.對於網格布局，GridLayoutManager 提供了一個 setSpanSizeLookup() 的方法，用來設置每個條目可以占用的列數，默認為1.

　　2.對於瀑布流，StaggeredGridLayoutManager 提供了一個 StaggeredGridLayoutManager.LayoutParams 內部靜態類，此類中有一個setFullSpan() 方法，用來設置條目跨越全列。

　　3.基類的實現方式如下：子類只需要重寫以下方法：

　　　　onCreateNormalViewHolder(ViewGroup parent);

　　　　onBindNormalViewHolder(RecyclerView.ViewHolder holder, int position);

  1 /**
  2  * Created by sunwei on 2015/12/4.
  3  * Email: [email protected].
  4  * Description: recycleView 滑動到底部加載更多
  5  */
  6 public abstract class BaseLoadingAdapter<T> extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
  7 
  8     private static final String TAG = "BaseLoadingAdapter";
  9 
 10     //是否正在加載
 11     private boolean mIsLoading = false;
 12     //正常條目
 13     private static final int TYPE_NORMAL_ITEM = 0;
 14     //加載條目
 15     private static final int TYPE_LOADING_ITEM = 1;
 16     //加載viewHolder
 17     private LoadingViewHolder mLoadingViewHolder;
 18     private StaggeredGridLayoutManager mStaggeredGridLayoutManager;
 19     //數據集
 20     private CircularArray<T> mTs;
 21 
 22     public BaseLoadingAdapter(RecyclerView recyclerView, CircularArray<T> ts) {
 23         mTs = ts;
 24 
 25         setSpanCount(recyclerView);
 26 
 27         setScrollListener(recyclerView);
 28     }
 29 
 30     private OnLoadingListener mOnLoadingListener;
 31 
 32     /**
 33      * 加載更多接口
 34      */
 35     public interface OnLoadingListener {
 36         void loading();
 37     }
 38 
 39     /**
 40      * 設置監聽接口
 41      *
 42      * @param onLoadingListener onLoadingListener
 43      */
 44     public void setOnLoadingListener(OnLoadingListener onLoadingListener) {
 45         mOnLoadingListener = onLoadingListener;
 46     }
 47 
 48     /**
 49      * 加載完成
 50      */
 51     public void setLoadingComplete() {
 52         mIsLoading = false;
 53         mTs.removeFromEnd(1);
 54         notifyItemRemoved(mTs.size() - 1);
 55     }
 56 
 57     /**
 58      * 沒有更多數據
 59      */
 60     public void setLoadingNoMore() {
 61         mLoadingViewHolder.progressBar.setVisibility(View.GONE);
 62         mLoadingViewHolder.tvLoading.setText("數據已加載完！");
 63     }
 64 
 65     /**
 66      * 加載失敗
 67      */
 68     public void setLoadingError() {
 69         if (mLoadingViewHolder != null) {
 70             mLoadingViewHolder.progressBar.setVisibility(View.GONE);
 71             mLoadingViewHolder.tvLoading.setText("加載失敗，點擊重新加載！");
 72 
 73             mLoadingViewHolder.tvLoading.setOnClickListener(new View.OnClickListener() {
 74                 @Override
 75                 public void onClick(View v) {
 76                     if (mOnLoadingListener != null) {
 77                         mLoadingViewHolder.progressBar.setVisibility(View.VISIBLE);
 78                         mLoadingViewHolder.tvLoading.setText("正在加載");
 79 
 80                         mOnLoadingListener.loading();
 81                     }
 82                 }
 83             });
 84         }
 85     }
 86 
 87     /**
 88      * @return Whether it is possible for the child view of this layout to
 89      * scroll up. Override this if the child view is a custom view.
 90      */
 91     private boolean canScrollDown(RecyclerView recyclerView) {
 92         return ViewCompat.canScrollVertically(recyclerView, 1);
 93     }
 94 
 95     /**
 96      * 設置每個條目占用的列數
 97      *
 98      * @param recyclerView recycleView
 99      */
100     private void setSpanCount(RecyclerView recyclerView) {
101         RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
102         if (layoutManager instanceof GridLayoutManager) {
103             final GridLayoutManager gridLayoutManager = (GridLayoutManager) layoutManager;
104             gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {
105                 @Override
106                 public int getSpanSize(int position) {
107                     int type = getItemViewType(position);
108                     if (type == TYPE_NORMAL_ITEM) {
109                         return 1;
110                     } else {
111                         return gridLayoutManager.getSpanCount();
112                     }
113                 }
114             });
115         }
116 
117         if (layoutManager instanceof StaggeredGridLayoutManager) {
118             mStaggeredGridLayoutManager = (StaggeredGridLayoutManager) layoutManager;
119         }
120     }
121 
122     /**
123      * 監聽滾動事件
124      *
125      * @param recyclerView recycleView
126      */
127     private void setScrollListener(RecyclerView recyclerView) {
128         recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
129             @Override
130             public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
131                 super.onScrollStateChanged(recyclerView, newState);
132             }
133 
134             @Override
135             public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
136                 super.onScrolled(recyclerView, dx, dy);
137 
138                 if (!canScrollDown(recyclerView)) {
139                     if (!mIsLoading) {
140                         mIsLoading = true;
141                         mTs.addLast(null);
142                         notifyItemInserted(mTs.size() - 1);
143                         if (mOnLoadingListener != null) {
144                             mOnLoadingListener.loading();
145                         }
146                     }
147                 }
148             }
149         });
150     }
151 
152     /**
153      * 創建viewHolder
154      *
155      * @param parent viewGroup
156      * @return viewHolder
157      */
158     public abstract RecyclerView.ViewHolder onCreateNormalViewHolder(ViewGroup parent);
159 
160     /**
161      * 綁定viewHolder
162      *
163      * @param holder   viewHolder
164      * @param position position
165      */
166     public abstract void onBindNormalViewHolder(RecyclerView.ViewHolder holder, int position);
167 
168     /**
169      * 加載布局
170      */
171     private class LoadingViewHolder extends RecyclerView.ViewHolder {
172         public ProgressBar progressBar;
173         public TextView tvLoading;
174         public LinearLayout llyLoading;
175 
176         public LoadingViewHolder(View view) {
177             super(view);
178 
179             progressBar = (ProgressBar) view.findViewById(R.id.progress_loading);
180             tvLoading = (TextView) view.findViewById(R.id.tv_loading);
181             llyLoading = (LinearLayout) view.findViewById(R.id.lly_loading);
182         }
183     }
184 
185     @Override
186     public int getItemViewType(int position) {
187         T t = mTs.get(position);
188         if (t == null) {
189             return TYPE_LOADING_ITEM;
190         } else {
191             return TYPE_NORMAL_ITEM;
192         }
193     }
194 
195     @Override
196     public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
197         if (viewType == TYPE_NORMAL_ITEM) {
198             return onCreateNormalViewHolder(parent);
199         } else {
200             View view = LayoutInflater.from(parent.getContext()).inflate(
201                     R.layout.loading_view, parent, false);
202             mLoadingViewHolder = new LoadingViewHolder(view);
203             return mLoadingViewHolder;
204         }
205     }
206 
207     @Override
208     public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
209         int type = getItemViewType(position);
210         if (type == TYPE_NORMAL_ITEM) {
211             onBindNormalViewHolder(holder, position);
212         } else {
213             if (mStaggeredGridLayoutManager != null) {
214                 StaggeredGridLayoutManager.LayoutParams layoutParams =
215                         new StaggeredGridLayoutManager.LayoutParams(
216                                 ViewGroup.LayoutParams.MATCH_PARENT,
217                                 ViewGroup.LayoutParams.WRAP_CONTENT);
218                 layoutParams.setFullSpan(true);
219 
220                 mLoadingViewHolder.llyLoading.setLayoutParams(layoutParams);
221             }
222         }
223     }
224 
225     @Override
226     public int getItemCount() {
227         return mTs.size();
228     }
229 }

　　4.一個簡單的列子

 1 /**
 2  * Created by sunwei on 2015/12/4.
 3  * Email: [email protected].
 4  * Description: 加載更多
 5  */
 6 public class DesignLoaderMoreAdapter extends BaseLoadingAdapter<DesignItem> {
 7 
 8     private CircularArray<DesignItem> mDesignItems;
 9 
10     public DesignLoaderMoreAdapter(RecyclerView recyclerView, CircularArray<DesignItem> datas) {
11         super(recyclerView, datas);
12 
13         mDesignItems = datas;
14     }
15 
16     //正常條目
17     public  class DesignViewHolder extends RecyclerView.ViewHolder {
18         public TextView  textView;
19         public CardView cardView;
20         public DesignViewHolder(View view) {
21             super(view);
22             textView = (TextView) view.findViewById(R.id.tv_design);
23             cardView = (CardView) view.findViewById(R.id.cardView_designer);
24 
25         }
26     }
27 
28     @Override
29     public RecyclerView.ViewHolder onCreateNormalViewHolder(ViewGroup parent) {
30         View view = LayoutInflater.from(parent.getContext()).inflate(
31                 R.layout.list_item_design, parent, false);
32         return new DesignViewHolder(view);
33     }
34 
35     @Override
36     public void onBindNormalViewHolder(RecyclerView.ViewHolder holder, int position) {
37         DesignViewHolder viewHolder = (DesignViewHolder)holder;
38         DesignItem designItem = mDesignItems.get(position);
39         if (position == 10) {
40             //設置瀑布流的條目大小
41             LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(260, 360);
42             lp.setMargins(10, 40, 10, 80);
43             viewHolder.cardView.setLayoutParams(lp);
44         }
45 
46         viewHolder.textView.setText(designItem.name);
47     }
48 }

項目地址：https://github.com/lxsunwei/MaterialDesignDemo