监听ViewPager滑动到首张或末张后继续滑动事件

imagePager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
          int lastState = -1;

          @Override
          public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
          }

          @Override
          public void onPageSelected(int position) {
              currItem = position;
          }

          @Override
          public void onPageScrollStateChanged(int state) {
              if (currItem == imageAdapter.getCount() - 1 && state == 0 && lastState == 1) {
                  ToastUtil.show("已经是最后一张了");
              }
              if (currItem == 0 && state == 0 && lastState == 1) {
                  ToastUtil.show("已经是第一张了");
              }
              lastState = state;
          }
      });