如何在App.js中创建不带函数的React.js应用

import React from 'react';
import ReactDOM from 'react-dom';

class App extends React.Component {
  render() {
    return (
      // JSX代码写在这里
    );
  }
}

render() {
  return (
    <div>
      <h1>Hello, React!</h1>
      <p>This is a React.js application.</p>
    </div>
  );
}

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

import React from 'react';
import ReactDOM from 'react-dom';

class App extends React.Component {
  render() {
    return (
      <div>
        <h1>Hello, React!</h1>
        <p>This is a React.js application.</p>
      </div>
    );
  }
}

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