对于v6：

import { Routes, Route, Navigate } from "react-router-dom";

function App() {
  return (
    <Routes>
      <Route path="/public" element={<PublicPage />} />
      <Route
        path="/protected"
        element={
          <RequireAuth redirectTo="/login">
            <ProtectedPage />
          </RequireAuth>
        }
      />
    </Routes>
  );
}

function RequireAuth({ children, redirectTo }) {
  let isAuthenticated = getAuth();
  return isAuthenticated ? children : <Navigate to={redirectTo} />;
}

问题

<BrowserRouter>
  <Switch>
    {authLogin ? (
      <>
        <Route path="/dashboard" component={Dashboard} exact />
        <Route exact path="/About" component={About} />
      </>
    ) : (
      <Route path="/" component={Login} exact />
    )}

    <Route component={PageNotFound} />
  </Switch>
</BrowserRouter>

Switch除了Route和Redirect组件之外，不会处理其他任何渲染。如果您想要像这样“嵌套”，那么您需要将每个组件包装在通用路由中，但这是完全不必要的。

您的登录组件还没有处理重定向回原来访问的“主页”或私有路由。

解决方案

react-router-dom v6

在版本6中，自定义路由组件已经不再受欢迎，首选方法是使用auth布局组件。

import { Navigate, Outlet } from 'react-router-dom';

const PrivateRoutes = () => {
  const location = useLocation();
  const { authLogin } = useContext(globalC);

  if (authLogin === undefined) {
    return null; // 或者加载指示器/旋转器等
  }

  return authLogin 
    ? <Outlet />
    : <Navigate to="/login" replace state={{ from: location }} />;
}

...

<BrowserRouter>
  <Routes>
    <Route path="/" element={<PrivateRoutes />} >
      <Route path="dashboard" element={<Dashboard />} />
      <Route path="about" element={<About />} />
    </Route>
    <Route path="/login" element={<Login />} />
    <Route path="*" element={<PageNotFound />} />
  </Routes>
</BrowserRouter>

或者

const routes = [
  {
    path: "/",
    element: <PrivateRoutes />,
    children: [
      {
        path: "dashboard",
        element: <Dashboard />,
      },
      {
        path: "about",
        element: <About />
      },
    ],
  },
  {
    path: "/login",
    element: <Login />,
  },
  {
    path: "*",
    element: <PageNotFound />
  },
];

...

export default function Login() {
  const location = useLocation();
  const navigate = useNavigate();
  const { authLogin, loginData } = useContext(globalC);

  useEffect(() => {
    if (authLogin) {
      const { from } = location.state || { from: { pathname: "/" } };
      navigate(from, { replace: true });
    }
  }, [authLogin, location, navigate]);

  return (
    <div
      style={{ height: "100vh" }}
      className="d-flex justify-content-center align-items-center"
    >
      <button type="button" onClick={loginData} className="btn btn-primary">
        登录
      </button>
    </div>
  );
}

react-router-dom v5

创建一个消费您的auth上下文的PrivateRoute组件。

const PrivateRoute = (props) => {
  const location = useLocation();
  const { authLogin } = useContext(globalC);

  if (authLogin === undefined) {
    return null; // 或者加载指示器/旋转器等
  }

  return authLogin ? (
    <Route {...props} />
  ) : (
    <Redirect
      to={{
        pathname: "/login",
        state: { from: location }
      }}
    />
  );
};

更新您的Login组件以处理重定向回原来访问的路由。

export default function Login() {
  const location = useLocation();
  const history = useHistory();
  const { authLogin, loginData } = useContext(globalC);

  useEffect(() => {
    if (authLogin) {
      const { from } = location.state || { from: { pathname: "/" } };
      history.replace(from);
    }
  }, [authLogin, history, location]);

  return (
    <div
      style={{ height: "100vh" }}
      className="d-flex justify-content-center align-items-center"
    >
      <button type="button" onClick={loginData} className="btn btn-primary">
        登录
      </button>
    </div>
  );
}

将所有路由渲染为“扁平列表”

function Routes() {
  return (
    <BrowserRouter>
      <Switch>
        <PrivateRoute path="/dashboard" component={Dashboard} />
        <PrivateRoute path="/About" component={About} />
        <Route path="/login" component={Login} />
        <Route component={PageNotFound} />
      </Switch>
    </BrowserRouter>
  );
}