使用Recyclerview实现图片水平自动循环滚动

简介：

本篇博客主要介绍的是如何使用RecyclerView实现图片水平方向自动循环（跑马灯效果）

效果图：

　　

思路：

1.准备m张图片

1.使用Recyclerview实现，返回无数个（实际Interge.MAXVALUE）item，第n个item显示第n%m张图片

3.使用recyclerview.scrollBy  每个一段时间水平滚动一段距离

4.通过layoutManager.findFirstVisibleItemPosition()获取当前显示的第一个View是第几个item,上面的ImageView显示对应de图片

　　

实现代码：

XML文件

1.activity布局文件activity_recy.xml

　　

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <ImageView
        android:layout_width="300dp"
        android:layout_height="350dp"
        android:layout_gravity="center_horizontal"
        android:id="@+id/img"
        android:src="@drawable/p5"
        android:scaleType="fitXY"
        />

        <android.support.v7.widget.RecyclerView
            android:layout_width="match_parent"
            android:layout_height="150dp"
            android:layout_marginTop="10dp"
            android:id="@+id/recyclerview"
            ></android.support.v7.widget.RecyclerView>

</LinearLayout>

2.适配器布局item_horizon.xml

　　

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:orientation="vertical"

    >
    <ImageView
        android:layout_width="100dp"
        android:layout_height="match_parent"
        android:id="@+id/img"
        android:layout_marginLeft="5dp"
        android:layout_marginRight="5dp"
        android:scaleType="fitXY"
        />

</LinearLayout>

Activity

　　

public class HorizontalActivity extends AppCompatActivity implements RecyAdapter.OnItemClickListener {
    private String TAG="HorizontalActivity";

    @BindView(R.id.img)
    ImageView img;
    @BindView(R.id.recyclerview)
    RecyclerView recyclerview;

    private Integer[] mImgIds = {R.drawable.p1, R.drawable.p2, R.drawable.p3, R.drawable.p4, R.drawable.p5,
            R.drawable.pic1, R.drawable.pic5, R.drawable.pic6};
    private List<Integer> datas;
    private RecyAdapter recyAdapter;
    private Handler mHandler=new Handler();
    private LinearLayoutManager layoutManager;

    private int oldItem=0;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_recy);
        ButterKnife.bind(this);
        initData();
        initRecy();
        img.setImageResource(datas.get(0));
        recyAdapter.setOnItemClickListener(this);
    }

    Runnable scrollRunnable=new Runnable() {
        @Override
        public void run() {
            recyclerview.scrollBy(3,0);

//            int firstItem = layoutManager.findFirstVisibleItemPosition();
            int firstItem=layoutManager.findFirstVisibleItemPosition();
            if(firstItem!=oldItem&&firstItem>0){
                oldItem=firstItem;
                img.setImageResource(datas.get(oldItem%datas.size()));
            }

            Log.e(TAG, "run: firstItem:"+firstItem );

            mHandler.postDelayed(scrollRunnable,10);
        }
    };

    private void initRecy() {
        recyAdapter=new RecyAdapter(this,datas);

        layoutManager = new LinearLayoutManager(this);
        layoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
        recyclerview.setLayoutManager(layoutManager);
        recyclerview.setAdapter(recyAdapter);
    }

    private void initData() {
        datas=new ArrayList<>();
        for (int i = 0; i <mImgIds.length ; i++) {
            datas.add(mImgIds[i]);
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        mHandler.postDelayed(scrollRunnable,10);
    }

    @Override
    protected void onStop() {
        super.onStop();
        mHandler.removeCallbacks(scrollRunnable);
    }

    @Override
    public void onItemClick(View view, int tag) {
        Toast.makeText(this,"第"+tag+"张图片被点击了",Toast.LENGTH_SHORT).show();
    }
}

适配器RecyAdapter

public class RecyAdapter extends RecyclerView.Adapter<RecyAdapter.ViewHolder> implements View.OnClickListener {

    private Context context;
    private List<Integer> datas;
    private OnItemClickListener onItemClickListener;

    public RecyAdapter(Context context, List<Integer> datas) {
        this.context = context;
        this.datas = datas;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.item_horizontal, parent, false);
        ViewHolder vh=new ViewHolder(view);
        view.setOnClickListener(this);
        return vh;
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        int newPos=position%datas.size();

        holder.img.setImageResource(datas.get(newPos));

        holder.itemView.setTag(position);

    }

    @Override
    public int getItemCount() {
        return Integer.MAX_VALUE;
    }

    @Override
    public void onClick(View view) {
        if(onItemClickListener!=null){
            onItemClickListener.onItemClick(view, (Integer) view.getTag());
        }
    }

    class ViewHolder extends RecyclerView.ViewHolder {
         ImageView img;
        public ViewHolder(View itemView) {
            super(itemView);
            img=itemView.findViewById(R.id.img);
        }
    }

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

    }
    interface OnItemClickListener{
        void onItemClick(View view,int tag);
    }

}