import React, { Component } from 'react';

class MyComponent extends Component {
  constructor(props) {
    super(props);
    this.state = {
      selectedValue: '' // 初始化状态变量
    };
  }

  handleChange = (event) => {
    this.setState({ selectedValue: event.target.value }); // 更新状态变量
  }

  render() {
    return (
      <div>
        <select value={this.state.selectedValue} onChange={this.handleChange}>
          <option value="option1">选项1</option>
          <option value="option2">选项2</option>
          <option value="option3">选项3</option>
        </select>
        <p>选择的值：{this.state.selectedValue}</p>
      </div>
    );
  }
}

export default MyComponent;