RecyclerView 下拉刷新和加载更多

一.SwipeRefreshLayout实现下拉刷新

1.方法API：

setOnRefreshListener(OnRefreshListener):添加下拉刷新监听器
setRefreshing(boolean):显示或者隐藏刷新进度条
isRefreshing():检查是否处于刷新状态
setColorSchemeResources():设置进度条的颜色主题，最多设置四种，以前的setColorScheme()方法已经弃用了。

2.简单使用：

<?xmlversionxmlversion="1.0" encoding="utf-8"?>
<LinearLayoutxmlns:androidLinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"android:layout_width="match_parent"
   android:layout_height="match_parent">
    <includelayoutincludelayout="@layout/common_top_bar_layout"/>
   <android.support.v4.widget.SwipeRefreshLayout
       android:id="@+id/demo_swiperefreshlayout"
       android:layout_width="fill_parent"
       android:layout_height="fill_parent"
        android:scrollbars="vertical"
        >
       <android.support.v7.widget.RecyclerView
           android:id="@+id/demo_recycler"
           android:layout_width="fill_parent"
           android:layout_height="fill_parent"
           ></android.support.v7.widget.RecyclerView>
   </android.support.v4.widget.SwipeRefreshLayout>
</LinearLayout>  

Java：

原理：是一个刷新布局，来自兼容包v4可以运行在低版本，控件如果想要支持下拉刷新，只要使用当前布局包裹 
setColorSchemeColors:修改旋转颜色，可以添加多种颜色 
setRefreshing: 是否显示loading状态 
setOnRefreshListener:下拉刷新监听

 public class MainActivity extends AppCompatActivity {
     private SwipeRefreshLayout swipeRefreshLayout;
     protected void onCreate(Bundle savedInstanceState) {
                  ·····
    swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.refresh_layout);
         //设置旋转的颜色效果
         swipeRefreshLayout.setColorSchemeColors(Color.GREEN, Color.YELLOW, Color.RED);
         //设置下拉刷新的监听器
         swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
             public void onRefresh() {
                 requestData();
             }
         });
     }
     private void requestData() {
         new Handler().postDelayed(new Runnable() {//延时加载
        public void run() {
                 String json = "{name:小米}";
                 TextView text = (TextView) findViewById(R.id.text);
                 text.setText(json);
                 swipeRefreshLayout.setRefreshing(false);//关闭显示
             }
         }, );
     }

二.加载更多——上滑加载数据 
思路：

1.滚动到底部 getItemCount()-2 ==bottomPosition 
2.不处理滚动中 
OnScrollListener监听滚动加载的监听器 
int dy 滚动距离，向上滚动为正 
layoutManager.findLastVisibleItemPosition获取处于底部数据的下标 
dy>0与isLoading 都是用来控件灵敏度

 public class HomeFragment extends Fragment {
         private SwipeRefreshLayout swipeRefreshLayout;
         private RecyclerView recyclerView;
         private AppAdapter adapter;
         @Override
         public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
                 //有一个显示网络状态
                 //StateLayout stateLayout  = new StateLayout(container.getContext());
             swipeRefreshLayout = new SwipeRefreshLayout(container.getContext());
             //设置颜色
             swipeRefreshLayout.setColorSchemeColors(Color.GREEN);
             //设置下拉监听
             swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
                 @Override
                 public void onRefresh() {
                     HttpConnect.get(ApiUrls.HOME+"?index=0", callback);
                 }
             });
             recyclerView = new RecyclerView(container.getContext());
             //设置排列规则
             recyclerView.setLayoutManager(new LinearLayoutManager(container.getContext()));
             //预先设置了Noemal视图，但是normal视图没有内容    stateLayout.addNormalView(recyclerView);
             swipeRefreshLayout.addView(recyclerView);
             //发送请求给服务器
             HttpConnect.get(ApiUrls.HOME+"?index=0",callback);
             return swipeRefreshLayout;
         }
         DefaultCallBack callback = new DefaultCallBack() {
             @Override
             public void onStart(int what) {
                 swipeRefreshLayout.setRefreshing(true);
             }
             @Override
             public void onFinish(int what) {
                 swipeRefreshLayout.setRefreshing(false);
             }
             //拿到数据
             protected void createView(String json) {
                 HomeWebInfo info = new Gson().fromJson(json, HomeWebInfo.class);
                 //创建控件，设置适配器
                 adapter=new AppAdapter(info.list);
                 recyclerView.setAdapter(adapter);
                 //上滑加载数据
                 addLoadMoreList();
             }
         };
         private void addLoadMoreList(){
         recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener(){
             private boolean isLoading = false;
            //int dy 上下滑动的距离 +数代表往上滑动
             public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                 super.onScrolled(recyclerView, dx, dy);
                 //判断 是否是排列布局
                 RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
                 //判断是否是线性排列，并且是否滑动距离
                 if(layoutManager instanceof  LinearLayoutManager && dy> ){
                     //当前是列表
                     int total = adapter.getItemCount();
                     int lastPosition = total-;
                     //获取rv 的bottom条目
                     int currLastPosition = ((LinearLayoutManager) layoutManager).findLastVisibleItemPosition();
                     if(currLastPosition==lastPosition&&!isLoading){      }
                     isLoading=true;
                     Toast.makeText(MyApp.getContext(),"加载更多...",Toast.LENGTH_SHORT).show();
                     new Handler().postDelayed(new Runnable() {
                         @Override
                         public void run() {
                             Toast.makeText(MyApp.getContext(), "加载成功", Toast.LENGTH_SHORT).show();
                             isLoading=false;
                         }
                     },);
                 }
             }
         });
       }
   }