ReactJs复选框在第一次使用后不会更改值

class MyComponent extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      isChecked: false
    };
    this.handleCheckboxChange = this.handleCheckboxChange.bind(this);
  }

  handleCheckboxChange(event) {
    this.setState({ isChecked: event.target.checked });
  }

  render() {
    return (
      <div>
        <input
          type="checkbox"
          checked={this.state.isChecked}
          onChange={this.handleCheckboxChange}
        />
        <label>Checkbox</label>
      </div>
    );
  }
}

constructor(props) {
  super(props);
  this.state = {
    isChecked: true
  };
}

<input type="checkbox" defaultValue={true} />