vue引入bootstrap报错 jQuery is not defined

webpack.base.conf.js

const webpack = require('webpack')
module.exports = {
...
 plugins: [
    new webpack.ProvidePlugin({
     $: "jquery",
     jQuery: "jquery"
    })
   ]
}

入口函数 main.js中

import $ from 'jquery'
import 'bootstrap/dist/css/bootstrap.min.css'
import 'bootstrap/dist/js/bootstrap.min.js'