NavLink 的使用：

<NavLink to="/" className="nav-item" exact activeClassName="nav-active">
  Main
</NavLink>

路由使用

render() {
   
    return (
      <BrowserRouter>
      <Nav />
        {
   /* <div className="container">hello,Dust.--App-index</div> */}
        <Switch>
            <Route path='/' exact component={
   Main}></Route>
            <Route path='/put' component={
   Put}></Route>
            <Route path='/open' component={
   Open}></Route>
            <Route component={
   NotFound} />
        </Switch>
      </BrowserRouter>
    )
  }