1.新建plugins、msg文件夹以及相关文件

• src/plugins/index.js
• src/plugins/msg/msg.vue

2.在msg.vue中实现消息通知的基本功能

• 点击按钮后弹出一个消息框，几秒之后消失

.msg.vue

<template>
  <div>
    <div class="msg" :class="{'active': msgStatus}">
      <div class="msg-wrapper">
        {{ text }}
      </div>
    </div>
  </div>
</template>

<script>
export default {
  name: 'vue-msg',
  data () {
    return {
      text: '',
      msgStatus: false
    }
  },
  methods: {
    msgPlugin (msg, time = 2000) {
      this.text = msg
      this.msgStatus = true
      setTimeout(() => {
        this.msgStatus = false
      }, time)
    }
  }
}
</script>

<style scoped>
  .msg {
    position: absolute;;
    left: 50%;
    top: 50%;
    transform: translate(-50%,50%);
    width:0px;
    min-height:0px;
    text-align:center;
    background-color:rgba(0,0,0,0.5);
    border-radius:5px;
    color: #fff;
    transition:all 0.5s;
    z-index:999;
    opacity:0;
  }
  .active {
    width:150px;
    min-height:25px;
    opacity:1;
    z-index:999;
  }
</style>

3.在plugins/index.js 导出插件

//比较简单的写法，后面进行优化
import msg from './msg/msg'

let plugin = {}

plugin.install = function (Vue) {
  Vue.component(msg.name, msg)
}
export default plugin

4.在main.js中引入该插件

import plugin from './plugins'

Vue.use(plugin)

5.在xxx.vue文件中使用vue-msg插件

<template>
  <div class="hello">
    <h1>this is hello word</h1>
    <input placeholder="请输入" v-model="name"/>
    <button @click="submit">提交</button>
    <vue-msg ref="msg"/>
  </div>
</template>

export default {
  name: 'HelloWorld',
  data () {
    return {
      name: ''
    }
  },
  methods: {
    submit () {
      if (!this.name) {
        this.$refs.msg.msgPlugin('姓名不能为空')
      }
    }
  }
}

至此已经完成一个插件的基本开发，但是实际工作中一定会需要在plugins/index.js中导入导出多个插件。第三步的写法不免有些繁琐。
下面提供一种更加优雅的写法

const  requireComponent = require.context('./', true, /\.vue$/)
const install = (Vue) => {
  if (install.installed) return
  install.installed
  requireComponent.keys().map(component => {
    const config = requireComponent(component)
    const componentName = config.default.name
    Vue.component(componentName, config.default || config)
  })
}
export default {
  install,
  // ...components
}

（完）