引言

  想要实现RecyclerView中的下拉刷新+上拉加载功能，我们除了使用谷歌提供给我们的SwipeRefreshLayout控件，还有一款相当漂亮的控件SmartRefreshLayout，它继承自SwipeRefreshLayout，但比原生的更强大。
  今天就来使用这款控件，实现RecyclerView的下拉刷新+上拉加载，讲真的，很漂亮！因为本期主要做刷新讲解，RecyclerView的相关代码请走传送门这边自行查看：RecyclerView实现代码传送门

效果预览

• 下拉刷新(经典头)

• 下拉刷新(谷歌头)

• 下拉刷新(雷达头)

• 上拉加载(经典尾)

• 上拉加载(脉冲尾)

用法

第一步：添加依赖(app下build.gradle中)

 //下拉刷新+上拉加载
    implementation 'androidx.appcompat:appcompat:1.2.0'                 //必须 1.0.0 以上
    implementation  'com.scwang.smart:refresh-layout-kernel:2.0.1'      //核心必须依赖
    implementation  'com.scwang.smart:refresh-header-classics:2.0.1'    //经典刷新头
    implementation  'com.scwang.smart:refresh-footer-classics:2.0.1'    //经典加载尾
    implementation  'com.scwang.smart:refresh-header-radar:2.0.1'       //雷达刷新头
    implementation  'com.scwang.smart:refresh-footer-ball:2.0.1'        //球脉冲加载尾
    implementation  'com.scwang.smart:refresh-header-falsify:2.0.1'     //虚拟刷新头
    implementation  'com.scwang.smart:refresh-header-material:2.0.1'    //谷歌刷新头
    implementation  'com.scwang.smart:refresh-header-two-level:2.0.1'   //二级刷新头

第二步：布局文件使用控件

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".blog.Case54"
    tools:ignore="MissingConstraints">

    <TextView
        android:id="@+id/title"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:background="@color/blue"
        android:gravity="center"
        android:text="RecyclerView中的下拉刷新、上拉加载"
        android:textColor="@color/white"
        android:textSize="20dp" />

    <com.scwang.smart.refresh.layout.SmartRefreshLayout
        android:id="@+id/refreshLayout"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@id/title">

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/recyclerview"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

    </com.scwang.smart.refresh.layout.SmartRefreshLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

第三步：在Activity中书写业务逻辑

//下拉刷新、上拉加载
public class Case54 extends AppCompatActivity {
    private RecyclerView recyclerView;
    private FruitRecyclerViewAdapter adapter;
    private LinearLayoutManager layoutManager;
    private List<Fruit> mList = new ArrayList();
    private int n = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_case54);

        initView();
        initData(n);
        setRecyclerView();
        setRefreshLayout();
    }
    private void initView(){
        recyclerView = findViewById(R.id.recyclerview);
    }
    private void initData(int n){
        for ( int i=1 ; i<13 ; i++){
            mList.add(new Fruit("apple"+(12*(n-1)+i),R.mipmap.apple));
        }
    }
    private void setRecyclerView(){
        //瀑布流布局
        adapter = new FruitRecyclerViewAdapter(mList);
        layoutManager = new LinearLayoutManager(this);
        layoutManager.setOrientation(RecyclerView.VERTICAL);
        recyclerView.setLayoutManager(layoutManager);
        recyclerView.setAdapter(adapter);
        recyclerView.setItemAnimator(new DefaultItemAnimator());
    }
    private void setRefreshLayout(){
        RefreshLayout refreshLayout = (RefreshLayout)findViewById(R.id.refreshLayout);
//        refreshLayout.setRefreshHeader(new ClassicsHeader(this)); //经典头
//        refreshLayout.setRefreshFooter(new ClassicsFooter(this)); //经典尾
        refreshLayout.setRefreshHeader(new BezierRadarHeader(this).setEnableHorizontalDrag(true));//雷达刷新头
//        refreshLayout.setRefreshHeader(new MaterialHeader(this));//谷歌刷新头
//        refreshLayout.setRefreshHeader(new TwoLevelHeader(this));//二级刷新头
        refreshLayout.setRefreshFooter(new BallPulseFooter(this).setSpinnerStyle(SpinnerStyle.Scale)); //脉冲尾

        refreshLayout.setOnRefreshListener(new OnRefreshListener() {
            @Override
            public void onRefresh(RefreshLayout refreshlayout) {
                mList.clear();
                refreshlayout.finishRefresh(2000/*,false*/);//传入false表示刷新失败
                initData(1);
            }
        });
        refreshLayout.setOnLoadMoreListener(new OnLoadMoreListener() {
            @Override
            public void onLoadMore(RefreshLayout refreshlayout) {
                dataRefresh();
                refreshlayout.finishLoadMore(2000/*,false*/);//传入false表示加载失败
            }
        });
    }
    private void dataRefresh(){
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(1000);//为了体现出刷新效果，所以这里休眠了线程
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                //切回主线程
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        initData(++n);//加载更多数据
                        adapter.notifyDataSetChanged();//通知数据已发生变化
                    }
                });
            }
        }).start();
    }
}

大功告成！