如何在扩展类中调用setState？

class MyComponent extends React.Component {
  handleClick = () => {
    this.setState({ count: this.state.count + 1 });
  }

  render() {
    return (
      <button onClick={this.handleClick}>增加计数</button>
    );
  }
}

class MyComponent extends React.Component {
  constructor(props) {
    super(props);
    this.handleClick = this.handleClick.bind(this);
  }

  handleClick() {
    this.setState({ count: this.state.count + 1 });
  }

  render() {
    return (
      <button onClick={this.handleClick}>增加计数</button>
    );
  }
}