reactjs – React Router不呈现Component

我想用登录创建一个React应用程序.为了维护用户状态,我想使用React 16.3引入的 Context API.在实施登录路由时,我遵循了 example in React Router documentation.

下面的源代码是(我希望)我的问题的一个非常简化的最小例子.当我在浏览器中打开localhost：3000 / protected时,URL会正确更改为localhost：3000 / login,但组件不会显示.似乎没有调用render()方法.

如何说服React渲染我的Login组件？

这是我的源代码.

App.js

import React, {Component} from 'react';
import {
    BrowserRouter as Router,
    Route
} from 'react-router-dom'
import Login from "./Login";
import Protected from "./Protected";
import ProtectedRoute from "./ProtectedRoute";
import UserContext from "./UserContext";

export default class App extends Component {
    render() {
        return (
            <Router>
                <UserContext.Provider value={false}>
                    <div>
                        <ProtectedRoute path='/protected' component={Protected}/>
                        <Route path='/login' component={Login}/>
                    </div>
                </UserContext.Provider>
            </Router>
        );
    }
}

Login.js

import React from 'react';

export default class Login extends React.Component {
    render() {
        return <p>Login</p>;
    }
}

UserContext.js

import React from "react";
const UserContext = React.createContext();
export default UserContext;

ProtectedRoute.js

import React from 'react'
import {Redirect, Route} from "react-router-dom";
import UserContext from './UserContext';

const ProtectedRoute = ({component: Component, ...rest}) => (
    <Route {...rest} render={props =>
        <UserContext.Consumer>
            {loggedIn =>
                loggedIn === true
                    ? <Component {...props} />
                    : <Redirect to={{
                        pathname: '/login',
                        state: {from: props.location}
                    }}/>
            }
        </UserContext.Consumer>
    }
    />
);

export default ProtectedRoute;

Protected.js

import React from 'react';

export default class Protected extends React.Component {
    render () {
        return <h2>protected</h2>;
    }
}

看起来这是一个错误： https://github.com/ReactTraining/react-router/issues/6072,甚至可能是一个React错误： https://github.com/facebook/react/issues/12551.

现在,您可以通过在单独的组件中呈现Router和您的上下文提供程序来解决它.像这样,例如：

const Routes = () => (
  <UserContext.Provider value={false}>
      <div>
          <ProtectedRoute path='/protected' component={Protected}/>
          <Route path='/login' component={Login}/>
      </div>
  </UserContext.Provider>
);

export default class App extends Component {
    render() {
        return (
            <Router>
              <Routes/>
            </Router>
        );
    }
}