show-overflow-tooltip
true：当内容过长被隐藏时显示 tooltip
false：默认值
<el-table-column label="文件路径" prop="filePath" align="center" width="220" show-overflow-tooltip=true>
</el-table-column>
也可以结合el-popover组件自己来实现
<el-table-column label="文件路径" prop="filePath" align="center" width="220">
<template slot-scope="scope">
<el-popover placement="top-start" title="文件路径" width="250" trigger="hover" >
<div>{{scope.row.filePath}}</div>
<span slot="reference">{{ scope.row.filePath.substr(0,30)+'...' }}</span>
</el-popover>
</template>
</el-table-column>
