从Material UI中的选择下拉菜单中删除悬停效果

Question

我将Material UI用于我的react项目，并使用Material UI文档中显示的选择下拉列表。单击第二组选择下拉菜单（本机选择）时，将显示默认的蓝色悬停效果。如何使用自定义主题从选择元素下拉菜单中禁用悬停效果？

import React from 'react';[![enter image description here][1]][1]
import PropTypes from 'prop-types';
import ReactDOM from 'react-dom';
import { withStyles } from '@material-ui/core/styles';
import OutlinedInput from '@material-ui/core/OutlinedInput';
import InputLabel from '@material-ui/core/InputLabel';
import FormControl from '@material-ui/core/FormControl';
import Select from '@material-ui/core/Select';


const styles = theme => ({
  root: {
    display: 'flex',
    flexWrap: 'wrap',
  },
  formControl: {
    margin: theme.spacing.unit,
    minWidth: 120,
  },
  selectEmpty: {
    marginTop: theme.spacing.unit * 2,
  },
});

class NativeSelects extends React.Component {
  state = {
    age: '',
    labelWidth: 0,
  };

  componentDidMount() {
    this.setState({
      labelWidth: ReactDOM.findDOMNode(this.InputLabelRef).offsetWidth,
    });
  }

  handleChange = name => event => {
    this.setState({ [name]: event.target.value });
  };

  render() {
    const { classes } = this.props;

    return (
      <div className={classes.root}>
        <FormControl className={classes.formControl}>
          <InputLabel htmlFor="age-native-simple">Age</InputLabel>
          <Select
            native
            value={this.state.age}
            onChange={this.handleChange('age')}
            inputProps={{
              name: 'age',
              id: 'age-native-simple',
            }}
          >
            <option value="" />
            <option value={10}>Ten</option>
            <option value={20}>Twenty</option>
            <option value={30}>Thirty</option>
          </Select>
        </FormControl>

        <FormControl variant="outlined" className={classes.formControl}>
          <InputLabel
            ref={ref => {
              this.InputLabelRef = ref;
            }}
            htmlFor="outlined-age-native-simple"
          >
            Age
          </InputLabel>
          <Select
            native
            value={this.state.age}
            onChange={this.handleChange('age')}
            input={
              <OutlinedInput
                name="age"
                labelWidth={this.state.labelWidth}
                id="outlined-age-native-simple"
              />
            }
          >
            <option value="" />
            <option value={10}>Ten</option>
            <option value={20}>Twenty</option>
            <option value={30}>Thirty</option>
          </Select>
        </FormControl>

      </div>
    );
  }
}

NativeSelects.propTypes = {
  classes: PropTypes.object.isRequired,
};

export default withStyles(styles)(NativeSelects);