如何在动态Antd表单中默认显示第一项？

import React, { Component } from 'react';
import { Form, Select } from 'antd';

class DynamicForm extends Component {
  constructor(props) {
    super(props);
    this.state = {
      selectedItemIndex: 0, // 默认选中第一项
    };
  }

  handleSelectChange = (value) => {
    this.setState({ selectedItemIndex: value });
  }

  render() {
    const { selectedItemIndex } = this.state;

    return (
      <Form>
        <Form.Item label="选择项">
          <Select value={selectedItemIndex} onChange={this.handleSelectChange}>
            <Select.Option value={0}>选项一</Select.Option>
            <Select.Option value={1}>选项二</Select.Option>
            <Select.Option value={2}>选项三</Select.Option>
          </Select>
        </Form.Item>

        {selectedItemIndex === 0 && (
          <Form.Item label="表单项一">
            {/* 表单项一的内容 */}
          </Form.Item>
        )}

        {selectedItemIndex === 1 && (
          <Form.Item label="表单项二">
            {/* 表单项二的内容 */}
          </Form.Item>
        )}

        {selectedItemIndex === 2 && (
          <Form.Item label="表单项三">
            {/* 表单项三的内容 */}
          </Form.Item>
        )}
      </Form>
    );
  }
}

export default DynamicForm;