RecyclerView的刷新分页

移动开发作者： 2024-08-25 02:40:01

在开发中常常使用到刷新分页，这里实现一个 RecyclerView 的简单的刷新分页操作，测试效果见文末，实现过程参考如下：实现思路加载更多数据使用到 RecyclerView 加载多种布局，根据 V

实现思路

加载更多数据使用到 RecyclerView 加载多种布局，根据 ViewType 判断加载数据 Item 还是加载 FooterItem ;
通过线程模拟加载数据;
为 RecyclerView 添加 addOnScrollListener 事件来监听用户的滑动操作;
根据用户滑动状态以及具体情况开始加载数据
通知数据更新;

如何获得 firstVisibleItemPosition

findFirstVisibleItemPosition()

findFirstCompletelyVisibleItemPosition()

findLastVisibleItemPosition()

findLastCompletelyVisibleItemPosition()

准备数据

    /**
     * 初始化数据
     * @return
     */
    public void  initData(){
        for (int i=0;i<30;i++){
            arrayList.add("第"+i+"条数据");
        }
    }

    /**
     * 线程模拟加载数据
     */
    class LoadDataThread extends Thread{
        @Override
        public void run() {
            initData();
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            //通知主线程更新数据
            Message message = handler.obtainMessage();
            message.what = UPDATE_DATA;
            message.obj = arrayList;
            handler.sendMessage(message);
        }
    }

代码参考

主布局


<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.manu.mrecyclerview.MainActivity">
    <android.support.v7.widget.RecyclerView
        android:id="@+id/rv"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </android.support.v7.widget.RecyclerView>
</LinearLayout>

Item布局

/**item.xml**/
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="5dp">
    <TextView
        android:id="@+id/tv_recycle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:text="data"
        android:background="#cac3c3"
        android:padding="10dp"
        android:textSize="20sp"/>
</LinearLayout>

/**item_footer.xml**/
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_horizontal">
    <ProgressBar
        style="?android:attr/progressBarStyleSmall"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/progressBar" />
    <TextView
        android:text="正在努力加载中，请稍后..."
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/textView" />
</LinearLayout>

Adapter

/**
 * Created by jzman on 2017/6/04
 * RecycleView的Adapter
 */
public class RvAdapter1 extends RecyclerView.Adapter<RecyclerView.ViewHolder> implements
        View.OnClickListener{
    private static final int ITEM_FOOTER = 0x1;
    private static final int ITEM_DATA = 0x2;
    private Context mContext;
    private RecyclerView recyclerView;
    private ArrayList<String> mList;

    public RvAdapter1() {}

    public RvAdapter1(Context mContext,ArrayList<String> mList) {
        this.mContext = mContext;
        this.mList = mList;
    }

    public void setmList(ArrayList<String> mList) {
        this.mList = mList;
    }

    /**
     * 用于创建ViewHolder
     * @param parent
     * @param viewTypez
     * @return
     */
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent,int viewType) {
        View view ;
        RecyclerView.ViewHolder vh = null;
        switch (viewType){
            case ITEM_DATA:
                view = LayoutInflater.from(mContext).inflate(R.layout.item,null);
                view.setOnClickListener(this);
                vh = new DataViewHolder(view);
                //使用代码设置宽高（xml布局设置无效时）
                view.setLayoutParams(new ViewGroup.LayoutParams(
                        ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.WRAP_CONTENT));
                break;
            case ITEM_FOOTER:
                view = LayoutInflater.from(mContext).inflate(R.layout.item_footer,null);
                //使用代码设置宽高（xml布局设置无效时）
                vh = new FooterViewHolder(view);
                view.setLayoutParams(new ViewGroup.LayoutParams(
                        ViewGroup.LayoutParams.MATCH_PARENT,ViewGroup.LayoutParams.WRAP_CONTENT));
                break;
        }
        return vh;
    }

    /**
     * 获取Item的View类型
     * @param position
     * @return
     */
    @Override
    public int getItemViewType(int position) {
        //根据 Item 的 position 返回不同的 Viewtype
        if (position == (getItemCount())-1){
            return ITEM_FOOTER;
        }else{
            return ITEM_DATA;
        }
    }

    /**
     * 绑定数据
     * @param holder
     * @param position
     */
    @Override
    public void onBindViewHolder(RecyclerView.ViewHolder holder,int position) {
        if (holder instanceof DataViewHolder){
            DataViewHolder dataViewHolder = (DataViewHolder) holder;
            dataViewHolder.tv_data.setText(mList.get(position));
        }else if (holder instanceof FooterViewHolder){

        }
    }

    /**
     * 选项总数
     * @return
     */
    @Override
    public int getItemCount() {
        return mList.size()+1;
    }

    @Override
    public void onClick(View view) {
        //根据RecyclerView获得当前View的位置
        int position = recyclerView.getChildAdapterPosition(view);
        //程序执行到此，会去执行具体实现的onItemClick()方法
        if (onItemClickListener!=null){
            onItemClickListener.onItemClick(recyclerView,view,position,mList.get(position));
        }
    }

    /**
     * 创建ViewHolder
     */
    public static class DataViewHolder extends RecyclerView.ViewHolder{
        TextView tv_data;
        public DataViewHolder(View itemView) {
            super(itemView);
            tv_data = (TextView) itemView.findViewById(R.id.tv_recycle);
        }
    }

    /**
     * 创建footer的ViewHolder
     */
    public static class FooterViewHolder extends RecyclerView.ViewHolder{
        public FooterViewHolder(View itemView) {
            super(itemView);
        }
    }

    private OnItemClickListener onItemClickListener;
    public void setOnItemClickListener(OnItemClickListener onItemClickListener){
        this.onItemClickListener = onItemClickListener;
    }

    /**
     * 定义RecyclerView选项单击事件的回调接口
     */
    public interface OnItemClickListener{
        //参数（父组件，当前单击的View,单击的View的位置，数据）
        void onItemClick(RecyclerView parent,View view,int position,String data);
    }
    /**
     *   将RecycleView附加到Adapter上
     */
    @Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
        this.recyclerView= recyclerView;
    }
    /**
     *   将RecycleView从Adapter解除
     */
    @Override
    public void onDetachedFromRecyclerView(RecyclerView recyclerView) {
        super.onDetachedFromRecyclerView(recyclerView);
        this.recyclerView = null;
    }
}

MainActivity

/**
 * Created by jzman on 2017/6/04 0013.
 */
public class MainActivity extends AppCompatActivity {
    private static final int UPDATE_DATA = 0x3;

    private RecyclerView rv;
    RvAdapter1 adapter;

    private ArrayList<String> arrayList = new ArrayList<>();
    //加载更多数据时最后一项的索引
    private int lastLoadDataItemPosition;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        rv = (RecyclerView) findViewById(R.id.rv);

        //设置布局管理器
        rv.setLayoutManager(new LinearLayoutManager(this));//线性
//        rv.setLayoutManager(new GridLayoutManager(this,4));//线性
//        rv.setLayoutManager(new StaggeredGridLayoutManager(4,StaggeredGridLayoutManager.VERTICAL));//线性
        initData();
        adapter = new RvAdapter1(this,arrayList);
        adapter.setOnItemClickListener(new RvAdapter1.OnItemClickListener() {
            @Override
            public void onItemClick(RecyclerView parent,String data) {
                Toast.makeText(MainActivity.this,data,Toast.LENGTH_SHORT).show();
            }
        });

        rv.addOnScrollListener(new OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView,int newState) {
                if (newState == SCROLL_STATE_IDLE &&
                        lastLoadDataItemPosition == adapter.getItemCount()){
                    new LoadDataThread().start();
                }
            }

            @Override
            public void onScrolled(RecyclerView recyclerView,int dx,int dy) {

                LayoutManager layoutManager = recyclerView.getLayoutManager();
                if (layoutManager instanceof LinearLayoutManager){
                    LinearLayoutManager manager = (LinearLayoutManager) layoutManager;
                    int firstVisibleItem = manager.findFirstVisibleItemPosition();
                    int l = manager.findLastCompletelyVisibleItemPosition();
                    lastLoadDataItemPosition = firstVisibleItem+(l-firstVisibleItem)+1;
                }
            }
        });

        rv.setAdapter(adapter);
    }

    /**
     * 初始化数据
     * @return
     */
    public void  initData(){
        for (int i=0;i<25;i++){
            arrayList.add("第"+i+"条数据");
        }
    }

    /**
     * 线程模拟加载数据
     */
    class LoadDataThread extends Thread{
        @Override
        public void run() {
            initData();
            try {
                Thread.sleep(2000);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            Message message = handler.obtainMessage();
            message.what = UPDATE_DATA;
            message.obj = arrayList;
            handler.sendMessage(message);
        }
    }

    private Handler handler = new Handler(){

        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what){
                case UPDATE_DATA:
                    arrayList = (ArrayList<String>) msg.obj;
                    adapter.setmList(arrayList);
                    adapter.notifyDataSetChanged();
                    break;
            }
        }
    };
}