需求：1. 鼠标悬浮到图示按钮上面，图片切换成灰色按钮
           2. 鼠标离开图示按钮，图片切换成回白色按钮

Html部分：

<!-- 如果此处的两个鼠标事件不生效，可以在mouseenter后面添加.native后缀 -->
<div class="left-btn"
     @click="saveTemplate()"
     @mouseenter="changeImageSrc(1, 'hover')"
     @mouseleave="changeImageSrc(1, '')">
  <img :src="saveTemplateSrc"
       class="left-btn-img"
       alt="">
  <span class="left-btn-text">保存模板</span>
</div>
<div class="left-btn"
     @click="deleteSelectStock()"
     @mouseenter="changeImageSrc(2, 'hover')"
     @mouseleave="changeImageSrc(2, '')">
  <img :src="deleteSelectStockSrc"
       class="left-btn-img"
       alt="">
  <span class="left-btn-text">删除选中行</span>
</div>
<div class="left-btn"
     @click="deleteTableData()"
     @mouseenter="changeImageSrc(3, 'hover')"
     @mouseleave="changeImageSrc(3, '')">
  <img :src="deleteTableDataSrc"
       class="left-btn-img"
       alt="">
  <span class="left-btn-text">清空当前表格</span>
</div>

Js部分：

// 在data中先定义图片的初始src
saveTemplateSrc: require("@/assets/dataBrowser/saveTemplate.png"),
deleteSelectStockSrc: require("@/assets/dataBrowser/deleteSelectedRow.png"),
deleteTableDataSrc: require("@/assets/dataBrowser/clearCurrentList.png")

// 在methods中绑定鼠标悬浮事件
changeImageSrc (key, way) {
  let tempStr = way === 'hover' ? 'Hover' : ''
  switch (key) {
    case 1:
      this.saveTemplateSrc = require(`@/assets/dataBrowser/saveTemplate${tempStr}.png`)
      break
    case 2:
      this.deleteSelectStockSrc = require(`@/assets/dataBrowser/deleteSelectedRow${tempStr}.png`)
      break
    case 3:
      this.deleteTableDataSrc = require(`@/assets/dataBrowser/clearCurrentList${tempStr}.png`)
      break
  }
}