ERROR in ./App.jsx
Module build Failed: SyntaxError: Only one default export allowed per module.

不知道如何解决它.谢谢.

=== App.jsx ====

import React from 'react';
import ReactDOM from 'react-dom';
import { Router,Route,Link,browserHistory,IndexRoute  } from 'react-router'

class App extends React.Component {
   render() {
      return (
         <div>
            <ul>
               <li><Link to = "/home">Home</Link></li>
               <li><Link to = "/about">About</Link></li>
               <li><Link to = "/contact">Contact</Link></li>
            </ul>

           {this.props.children}
         </div>
      )
   }
}

export default App;

class Home extends React.Component {
   render() {
      return (
         <div>
            <h1>Home...</h1>
         </div>
      )
   }
}

export default Home;

class About extends React.Component {
   render() {
      return (
         <div>
            <h1>About...</h1>
         </div>
      )
   }
}

export default About;

class Contact extends React.Component {
   render() {
      return (
         <div>
            <h1>Contact...</h1>
         </div>
      )
   }
}

export default Contact;

=== main.js ===

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App.jsx';

ReactDOM.render(<App/>,document.getElementById('app'));

UPDATE1

我注释掉了所有导出默认值,并在最后添加了以下内容

module.exports = {
    App: App,Home: Home,About: About,Contact: Contact
}

现在没有编译错误,但网页是空白的.我不确定这里有什么问题.