import { HashRouter as Router, Route, hashHistory } from 'react-router-dom'
页面就会报错Attempted import error: 'hashHistory' is not exported from 'react-router'.
原因react-router4现在不支持hashHistory了，解决办法如下：
import createHashHistory from 'history/createHashHistory';
const hashHistory = createHashHistory();
但是又提示Warning: Please use require("history").createHashHistory instead of require("history/createHashHistory"). Support for the latter will be removed in the next major release.如下改一下：
import { createHashHistory } from 'history';
const hashHistory = createHashHistory();
此时 Warning: <HashRouter> ignores the history prop. To use a custom history, use import { Router } instead of import { HashRouter as Router }.
OK，暂时解决眼前的问题。
