先做记录，后面有时间在仔细研究
https://www.cnblogs.com/jiangjh5/p/7209315.html?utm_source=itdadao&utm_medium=referral
https://blog.csdn.net/stypace/article/details/8947634
https://www.cnblogs.com/yaoyu126/p/7524625.html
注意本地文件要使用 "file:///*****"
url_string = "file:///D:/qt5/201709/webengine/test.html"
原文：https://www.cnblogs.com/zhangxuan/p/9167047.html