api 25 PopupWindow会占据整个屏幕

解决方法:
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) { // Android 7.x中,PopupWindow高度为match_parent时,会出现兼容性问题,需要处理兼容性
 int[] mLocation = new int[2];
 stephenCommonTopTitleView.getTopTitleView().getLocationInWindow(mLocation);
 int offsetY = mLocation[1] + stephenCommonTopTitleView.getTopTitleView().getHeight();
 if (Build.VERSION.SDK_INT >= 25) { // Android 7.1中，PopupWindow高度为 match_parent 时，会占据整个屏幕
 //故而需要在 Android 7.1上再做特殊处理
 WindowManager wm = (WindowManager) activity.getSystemService(Context.WINDOW_SERVICE);
 int screenHeight = wm.getDefaultDisplay().getHeight();
 centWinShare.setHeight(screenHeight - offsetY); // 重新设置 PopupWindow 的高度
 }
centWinShare.showAtLocation(stephenCommonTopTitleView.getTopTitleView(), Gravity.NO_GRAVITY, 0, offsetY);
} else {
centWinShare.showAsDropDown(stephenCommonTopTitleView.getTopTitleView());
}

思路大概是这样
/*if (Build.VERSION.SDK_INT != 24) {
 //只有24这个版本有问题，好像是源码的问题
 showAsDropDown(view);
} else {
 //7.0 showAsDropDown没卵子用 得这么写
 int[] location = new int[2];
 view.getLocationOnScreen(location);
 int x = location[0];
 int y = location[1];
 showAtLocation(view, Gravity.NO_GRAVITY, 0, y + view.getHeight());
 //showAsDropDown(view, 0, marginTop);
}*/