如何使用嵌套路由和私有路由组件在react.js中正确构造路由？

npm install react-router-dom

import { BrowserRouter as Router, Route, Switch } from 'react-router-dom';

const Home = () => <div>Home</div>;
const About = () => <div>About</div>;
const Contact = () => <div>Contact</div>;

const App = () => {
  return (
    <Router>
      <Switch>
        <Route exact path="/" component={Home} />
        <Route path="/about" component={About} />
        <Route path="/contact" component={Contact} />
      </Switch>
    </Router>
  );
};

import { Link } from 'react-router-dom';

const Navigation = () => {
  return (
    <nav>
      <ul>
        <li>
          <Link to="/">Home</Link>
        </li>
        <li>
          <Link to="/about">About</Link>
        </li>
        <li>
          <Link to="/contact">Contact</Link>
        </li>
      </ul>
    </nav>
  );
};

const App = () => {
  return (
    <Router>
      <Navigation />
      <Switch>
        <Route exact path="/" component={Home} />
        <Route path="/about" component={About} />
        <Route path="/contact" component={Contact} />
      </Switch>
    </Router>
  );
};