问React-router如何重定向到Express GET

EN

import React from 'react';
import ReactDOM from 'react-dom';
import App from './components/App';
import { BrowserRouter } from "react-router-dom";

// In production, we want to hydrate instead of render
// because of the server-rendering
if (process.env.NODE_ENV === 'production') {
  ReactDOM.hydrate(
    <BrowserRouter>
      <App {...window.__APP_INITIAL_STATE__} />
    </BrowserRouter>
  , document.getElementById('app'));
} else {
  ReactDOM.render(
    <BrowserRouter>
      <App {...window.__APP_INITIAL_STATE__} />
    </BrowserRouter>
  , document.getElementById('app'));
}

// Hot reload is that easy with Parcel
if (module.hot) {
  module.hot.accept();
}

app.get('/signup', (req,res)=>{
  const initialState = {component:'SignUp'};
  let context = {};

  const markup = ReactDOM.renderToString(
    <StaticRouter location={req.url}  context={context}>
      <App {...initialState} />
    </StaticRouter>
  );

  if (context.url) {
    res.writeHead(302, {
      Location: context.url
    });
    res.end();
  }
  else {
    res.send(generateHtml(markup,initialState));
  }
});

render(){
    return this.state.redirect ? <Redirect to="/login" /> :(
    <div className="ro">HI </div> );
}

export default class App extends Component {

  constructor(props){
    super(props);
    console.log(props);
  }

  render(){
    if(this.props.component === 'Root'){
      return <Root />;
    }
    else if(this.props.component === 'Login'){
      return <Login />;
    }
    else if(this.props.component === 'SignUp'){
      return <SignUp />;
    }
    else{
      return (
      <div>
        <h1>Hello word {this.props.component}</h1>
        <Button color="danger">Danger!</Button>
      </div>
     );
    }

  }

}