public class MainActivity extends RelativeLayout{        private Scroller scroller;    private Context context;    private int width;    private int height;    private ImageView imageView;        private int mLastDownY = 0;            private int mCurryY;        private int mDelY;        private boolean mCloseFlag = false;        public Main_skip(Context context, AttributeSet attrs) {        super(context, attrs);        this.context = context;        initView();    }        private void initView(){        // 这个Interpolator你可以设置别的 我这里选择的是有弹跳效果的Interpolator         BounceInterpolator interpolator = new BounceInterpolator();        scroller = new Scroller(context,interpolator);                        WindowManager manager = (WindowManager) context                .getSystemService(Context.WINDOW_SERVICE);        DisplayMetrics metrics = new DisplayMetrics();        manager.getDefaultDisplay().getMetrics(metrics);        width = metrics.widthPixels;        height = metrics.heightPixels;                // 这里你一定要设置成透明背景,不然会影响你看到底层布局          this.setBackgroundColor(Color.argb(0, 0, 0, 0));        imageView = new ImageView(context);        LayoutParams params = new LayoutParams(LayoutParams.MATCH_PARENT                , LayoutParams.MATCH_PARENT);        imageView.setLayoutParams(params);        imageView.setScaleType(ScaleType.FIT_XY);        imageView.setImageResource(R.drawable.a);        addView(imageView);                    }    public void setBGimg(int resID){        imageView.setImageResource(resID);    }        public void setBGimg(Drawable drawable){        imageView.setImageDrawable(drawable);    }        // 推动门的动画      public void setAnimation(int startY, int dy, int duration){        scroller.startScroll(0, startY, 0, dy, duration);        invalidate();    }            @Override    public boolean onTouchEvent(MotionEvent event) {        switch (event.getAction()) {        case MotionEvent.ACTION_DOWN:            mLastDownY = (int) event.getY();            System.err.println("ACTION_DOWN=" + mLastDownY);             return true;        case MotionEvent.ACTION_MOVE:            mCurryY = (int) event.getY();            System.err.println("ACTION_MOVE=" + mCurryY);            mDelY = mCurryY - mLastDownY;            if(mDelY < 0 ){                scrollTo(0, -mDelY);                 System.err.println("-------------  " + mDelY);              }            break;        case MotionEvent.ACTION_UP:            mCurryY = (int) event.getY();            mDelY = mCurryY - mLastDownY;             if(mDelY < 0){                if(Math.abs(mDelY)>height/2){                    setAnimation(this.getScrollY(), height, 450);                    mCloseFlag = true;                }else{                    setAnimation(this.getScrollY(), -this.getScrollY(), 1000);                }            }            break;        default:            break;        }        return super.onTouchEvent(event);    }            @Override    public void computeScroll() {        if(scroller.computeScrollOffset()){            scrollTo(scroller.getCurrX(), scroller.getCurrY());            // 不要忘记更新界面              postInvalidate();          }else {              if (mCloseFlag) {                  this.setVisibility(View.GONE);              }         }        super.computeScroll();    }}