如何在ReactJS中保存输入默认值

class MyComponent extends React.Component {
  constructor(props) {
    super(props);
    this.state = { defaultValue: '默认值' };
  }

  render() {
    return (
      <input type="text" defaultValue={this.state.defaultValue} />
    );
  }
}

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

  componentDidMount() {
    this.inputRef.current.value = '默认值';
  }

  render() {
    return (
      <input type="text" ref={this.inputRef} />
    );
  }
}

class MyComponent extends React.Component {
  constructor(props) {
    super(props);
    this.state = { value: '默认值' };
    this.handleChange = this.handleChange.bind(this);
  }

  handleChange(event) {
    this.setState({ value: event.target.value });
  }

  render() {
    return (
      <input type="text" value={this.state.value} onChange={this.handleChange} />
    );
  }
}