无法在react中使用this.ref.current.value获取输入字段的值

import React, { Component } from "react";

class MyForm extends Component {
  constructor(props) {
    super(props);
    this.state = {
      inputValue: ""
    };
  }

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

  handleSubmit = (event) => {
    event.preventDefault();
    console.log(this.state.inputValue); // 获取输入字段的值
  };

  render() {
    return (
      <form onSubmit={this.handleSubmit}>
        <input
          type="text"
          value={this.state.inputValue}
          onChange={this.handleChange}
        />
        <button type="submit">提交</button>
      </form>
    );
  }
}

import React, { Component, createRef } from "react";

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

  handleSubmit = (event) => {
    event.preventDefault();
    console.log(this.inputRef.current.value); // 获取输入字段的值
  };

  render() {
    return (
      <form onSubmit={this.handleSubmit}>
        <input type="text" ref={this.inputRef} />
        <button type="submit">提交</button>
      </form>
    );
  }
}