react 渲染路由的方法：
HashRouter hash实现路由
BrowserRouter H5 Api实现路由跳转
addEventListener(‘hashchange’);
histor.pushState({p:path})
add(‘popstate’, e => {
})
context.js
HashRouter.js
新增的方法：
{Provider , Consumer} React.createContext();
export {Provider, Consumer}
export default class HashRouter extends Component{
constructor(){
super();
}
}
Route.js
return
{state=>{
}}
