//自定义adapter
public class ImageAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> 
 
//或者使用其他三方框架，都是支持的，如：BRVAH
public class ImageAdapter extends BaseQuickAdapter<String, BaseViewHolder> {
    public ImageAdapter() {
        super(R.layout.item_image);
    }
    @Override
    protected void convert(@NonNull BaseViewHolder helper, String item) {
        Glide.with(mContext)
                .load(item)
                .into((ImageView) helper.getView(R.id.img));
    }
}

 @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        banner = findViewById(R.id.banner);
        
        //使用内置Indicator
        IndicatorView indicator = new IndicatorView(this)
              .setIndicatorColor(Color.DKGRAY)
              .setIndicatorSelectorColor(Color.WHITE);
        
        //创建adapter
     	 ImageAdapter adapter = new ImageAdapter();
     	 
     	 //传入RecyclerView.Adapter 即可实现无限轮播
         banner.setIndicator(indicator)
              .setAdapter(adapter);
    }

//设置左右页面露出来的宽度及item与item之间的宽度
.setPageMargin(UIUtil.dip2px(this, 20), UIUtil.dip2px(this, 10))
//内置ScaleInTransformer，设置切换缩放动画
.setPageTransformer(true, new ScaleInTransformer())
    

//单独设置OverlapSliderTransformer，项目里有，可以拷贝到项目中使用 kotlin实现的-。-
 .addPageTransformer(new OverlapSliderTransformer(banner.getViewPager2().getOrientation(), 0.25f, 0, 1,0))

    .setIndicatorRatio(1f) //ratio，默认值是1 ，也就是说默认是圆点，根据这个值，值越大，拉伸越长，就成了矩形，小于1，就变扁了呗
    .setIndicatorRadius(2f) // radius 点的大小
    .setIndicatorSelectedRatio(3) 
    .setIndicatorSelectedRadius(2f)
    .setIndicatorStyle(IndicatorView.IndicatorStyle.INDICATOR_BIG_CIRCLE)       

/**
 * 可以实现该接口，自定义Indicator 可参考内置的{@link IndicatorView}
 */
public interface Indicator {

    /**
     * 当数据初始化完成时调用
     *
     * @param pagerCount pager数量
     */
    void initIndicatorCount(int pagerCount);

    /**
     * 返回一个View，添加到banner中
     */
    View getView();

    /**
     * banner是一个RelativeLayout，设置banner在RelativeLayout中的位置，可以是任何地方
     */
    RelativeLayout.LayoutParams getParams();
    
    void onPageScrolled(int position, float positionOffset, @Px int positionOffsetPixels);
    
    void onPageSelected(int position);
    
    void onPageScrollStateChanged(int state);
}

//举个栗子
public class IndicatorView extends View implements Indicator{
       
        @Override
        public void initIndicatorCount(int pagerCount) {
            this.pagerCount = pagerCount;
            setVisibility(pagerCount > 1 ? VISIBLE : GONE);
            requestLayout();
        }
    
        @Override
        public View getView() {
            return this;
        }
         /**
          * 控制Indicator在Banner中的位置，开发者自行实现
          */
        @Override
        public RelativeLayout.LayoutParams getParams() {
            if (params == null) {
                params = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);
                params.addRule(RelativeLayout.ALIGN_PARENT_BOTTOM);
                params.addRule(RelativeLayout.CENTER_HORIZONTAL);
                params.bottomMargin = dip2px(10);
            }
            return params;
        }
        /**
          * banner切换时同步回调的三个方法
          */
        @Override
        public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
            selectedPage = position;
            offset = positionOffset;
            invalidate();
        }
        
        @Override
        public void onPageSelected(int position) {
        }
        
        @Override
        public void onPageScrollStateChanged(int state) {
        }
}