父状态更改时，子组件不会更新

class ChildComponent extends React.Component {
  componentDidUpdate(prevProps) {
    if (prevProps.parentState !== this.props.parentState) {
      // 更新子组件的逻辑
    }
  }

  render() {
    // 子组件的渲染逻辑
  }
}

const ParentContext = React.createContext();

class ParentComponent extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      parentState: 'value',
    };
  }

  render() {
    return (
      <ParentContext.Provider value={this.state.parentState}>
        <ChildComponent />
      </ParentContext.Provider>
    );
  }
}

class ChildComponent extends React.Component {
  static contextType = ParentContext;

  render() {
    const parentState = this.context;
    // 子组件的渲染逻辑
  }
}