@Override
 public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX, float velocityY) {
   if (this.getChildCount() > 0 && isTouchEnable) {
     // 根据划动量,切换viewflow
     if (e2.getX() - e1.getX() > 120) { // 从左向右滑动(左进右出)
       this.setInAnimation(mLeftInAnim);
       this.setOutAnimation(mRightOutAnim);
       if (this.getCurrentView().hashCode() == getChildAt(0).hashCode()) {
         if (onPageListener != null) {
           onPageListener.onStartPageListener();
         }
       } else {
         this.showPrevious();
       }
     } else if (e2.getX() - e1.getX() < -120) { // 从右向左滑动(右进左出)
       showNextPage();
     }
   }
   // this.flipStart();
   return true;
 }