不需要使用引用，你可以使用事件访问

function handleSubmit(e) {
    e.preventDefault()
    const {username, password } = e.target.elements
    console.log({username: username.value, password: password.value })
}

<form onSubmit={handleSubmit}>
   <input type="text" id="username"/>
   <input type="text" id="password"/>
   <input type="submit" value="Login" />
</form>

在javascript的许多事件中，我们有event，它给出一个对象，包括发生了什么事件，值是什么等等。

这也是我们在ReactJs中使用的表单…

所以在你的代码中，你将状态设置为新值…就像这样:

class UserInfo extends React.Component {

  constructor(props) {
    super(props);
    this.handleLogin = this.handleLogin.bind(this);
  }

  handleLogin(e) {
    e.preventDefault();
    for (const field in this.refs) {
      this.setState({this.refs[field]: this.refs[field].value});
    }
  }

  render() {
    return (
        <div>
          <form onSubmit={this.handleLogin}>
            <input ref="email" type="text" name="email" placeholder="Email" />
            <input ref="password" type="password" name="password" placeholder="Password" />
            <button type="button">Login</button>
          </form>
        </div>
    );
  }
}

export default UserInfo;

另外，这是React v.16中的表单示例，只是作为将来创建表单的参考:

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

    this.handleChange = this.handleChange.bind(this);
    this.handleSubmit = this.handleSubmit.bind(this);
  }

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

  handleSubmit(event) {
    alert('A name was submitted: ' + this.state.value);
    event.preventDefault();
  }

  render() {
    return (
      <form onSubmit={this.handleSubmit}>
        <label>
          Name:
          <input type="text" value={this.state.value} onChange={this.handleChange} />
        </label>
        <input type="submit" value="Submit" />
      </form>
    );
  }
}

下面是我使用单个inputChangeHandler收集多个表单输入的方法

import React from "react";

const COLORS = ["red", "orange", "yellow", "purple", "green", "white", "black"];

export default function App() {

  const initialFormFields = {
    name: undefined,
    email: undefined,
    favourite_color: undefined
  };
  const [formInput, setFormInput] = React.useState(initialFormFields);

  function inputChangeHandler(event) {
    setFormInput(prevFormState => ({
      ...prevFormState,
      [event.target.name]: event.target.value
    }))
  };

  return (
    <div className="App">
      <form>
        <label>Name: <input name="name" type="text" value={formInput.name} onChange={inputChangeHandler}/></label>
        <label>Email: <input name="email" type="email" value={formInput.email} onChange={inputChangeHandler}/></label>
        <div>
          {COLORS.map(color => <label><input type="radio" name="favourite_color" value={color} key={color} onChange={inputChangeHandler}/> {color} </label>)}
        </div>
      </form>

      <div>
        Entered Name: {formInput.name}
        Entered Email: {formInput.email}
        Favourite Color: {formInput.favourite_color}
      </div>
    </div>
  );
}

如果你在项目中使用Redux，你可以考虑使用这个更高阶的组件https://github.com/erikras/redux-form。

我认为这也是你需要的答案。此外，我在这里添加了所需的属性。每个输入组件都是函数。你需要在这里加入你自己的逻辑。

handleEmailChange: function(e) {
    this.setState({email: e.target.value});
},
handlePasswordChange: function(e) {
   this.setState({password: e.target.value});
},
formSubmit : async function(e) {
    e.preventDefault();
    // Form submit Logic
  },
render : function() {
      return (
        <form onSubmit={(e) => this.formSubmit(e)}>
          <input type="text" name="email" placeholder="Email" value={this.state.email} onChange={this.handleEmailChange} required />
          <input type="password" name="password" placeholder="Password" value={this.state.password} onChange={this.handlePasswordChange} required />
          <button type="button">Login</button>
        </form>);
},
handleLogin: function() {
    //Login Function
}

像这样给你的输入参考

<input type="text" name="email" placeholder="Email" ref="email" />
<input type="password" name="password" placeholder="Password" ref="password" />

然后你可以像soo一样在你的handleLogin中访问它

handleLogin: function(e) {
   e.preventDefault();
    console.log(this.refs.email.value)
    console.log(this.refs.password.value)
}