RecyclerView 实现下拉刷新和自动加载
魔鬼旋律
9年前
来自: http://android.jobbole.com/82442/
RecyclerView是 Android 兼容包V21中新推出的列表类,它的自定义化强的优点足以让它能够取代GridView和ListView,本文将结合SwipeRefreshLayout与RecyclerView讲解如何实现下拉刷新和自动加载的代码
需要的依赖
以下版本自行更新
Java
compile 'com.android.support:appcompat-v7:21.0.0' compile 'com.android.support:recyclerview-v7:21.0.0' compile 'com.android.support:cardview-v7:21.0.0' compile 'com.android.support:support-v4:21.0.0'
compile 'com.android.support:appcompat-v7:21.0.0' compile 'com.android.support:recyclerview-v7:21.0.0' compile 'com.android.support:cardview-v7:21.0.0' compile 'com.android.support:support-v4:21.0.0'</div>
需要解决的问题
- [x] 下拉刷新
- [x] 自动加载
- [x] 网络请求异步加载
技术处理
下拉刷新
采用 android.support.v4.widget.SwipeRefreshLayout 来实现
具体可以搜索这个class,我们按照官方文档,布局如下
Java
<view xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/swipeRefreshLayout" class="android.support.v4.widget.SwipeRefreshLayout" android:layout_width="match_parent" android:layout_height="match_parent"> <view xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/recylerView" class="android.support.v7.widget.RecyclerView" android:layout_width="wrap_content" android:layout_height="wrap_content"></view> </view>
<viewxmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/swipeRefreshLayout" class="android.support.v4.widget.SwipeRefreshLayout" android:layout_width="match_parent" android:layout_height="match_parent"> <viewxmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/recylerView" class="android.support.v7.widget.RecyclerView" android:layout_width="wrap_content" android:layout_height="wrap_content"></view> </view></div>
然后对 swipeRefreshLayout 设置监听即可
Java
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() { @Override public void onRefresh() { if(isrefreshing){ Log.d(TAG,"ignore manually update!"); } else{ loadPage(); } } });
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() { @Override public void onRefresh() { if(isrefreshing){ Log.d(TAG,"ignore manually update!"); } else{ loadPage(); } } });</div>
自动加载
RecyclerView是一个新兴事物,伸手党们还找不到 endless-RecyclerView 这样的开源神器,只好自己找方法了,同ListView一样,还是重写 OnScrollListener 这个方法
Java
recyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() { @Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) { super.onScrolled(recyclerView, dx, dy); int lastVisibleItem = ((LinearLayoutManager) mLayoutManager).findLastVisibleItemPosition(); int totalItemCount = mLayoutManager.getItemCount(); //lastVisibleItem >= totalItemCount - 4 表示剩下4个item自动加载,各位自由选择 // dy>0 表示向下滑动 if (lastVisibleItem >= totalItemCount - 4 && dy > 0) { if(isLoadingMore){ Log.d(TAG,"ignore manually update!"); } else{ loadPage();//这里多线程也要手动控制isLoadingMore isLoadingMore = false; } } } });
recyclerView.setOnScrollListener(new RecyclerView.OnScrollListener() { @Override public void onScrolled(RecyclerViewrecyclerView, int dx, int dy) { super.onScrolled(recyclerView, dx, dy); int lastVisibleItem = ((LinearLayoutManager) mLayoutManager).findLastVisibleItemPosition(); int totalItemCount = mLayoutManager.getItemCount(); //lastVisibleItem >= totalItemCount - 4 表示剩下4个item自动加载,各位自由选择 // dy>0 表示向下滑动 if (lastVisibleItem >= totalItemCount - 4 && dy > 0) { if(isLoadingMore){ Log.d(TAG,"ignore manually update!"); } else{ loadPage();//这里多线程也要手动控制isLoadingMore isLoadingMore = false; } } } });</div>
如果想用GridView,可以试试这个,注意例子里的span_count =2
Java
@Override public void onScrolled(RecyclerView recyclerView, int dx, int dy) { super.onScrolled(recyclerView, dx, dy); int[] visibleItems = mLayoutManager.findLastVisibleItemPositions(null); int lastitem = Math.max(visibleItems[0],visibleItems[1]); Log.d(TAG,"visibleItems =" + visibleItems); Log.d(TAG,"lastitem =" + lastitem); Log.d(TAG,"adapter.getItemCount() =" + adapter.getItemCount()); if (dy > 0 && lastitem > adapter.getItemCount() - 5 && !isLoadingMore) { Log.d(TAG,"will loadNewFeeds"); } }
@Override public void onScrolled(RecyclerViewrecyclerView, int dx, int dy) { super.onScrolled(recyclerView, dx, dy); int[] visibleItems = mLayoutManager.findLastVisibleItemPositions(null); int lastitem = Math.max(visibleItems[0],visibleItems[1]); Log.d(TAG,"visibleItems =" + visibleItems); Log.d(TAG,"lastitem =" + lastitem); Log.d(TAG,"adapter.getItemCount() =" + adapter.getItemCount()); if (dy > 0 && lastitem > adapter.getItemCount() - 5 && !isLoadingMore) { Log.d(TAG,"will loadNewFeeds"); } }</div>
网络请求异步加载
我这里的 loadPage 是基于 Retrofit 构建的,输入参数是一个Map,它的回调功能非常实用,可以直接控制UI更新,流程图如下,大家可以参考一下设计
loadPage 流程图
参考文献
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