写一个工具类，放到src/utils文件夹下新建文件previewDownFile.js

import axios from "axios";
import { ElMessage} from "element-plus";
 
export function previewBtn(url,fileName) { // url-下载预览地址 fileName-文件名
    if (!fileName) { // 图片预览
        window.open(url);
  }else{  // 文件下载
    axios({
      url,
      method: "GET",
      responseType: "blob"
    })
      .then(res => {
        const elink = document.createElement("a");
        elink.download = fileName;
        elink.style.display = "none";
        elink.href = URL.createObjectURL(res.data);
        document.body.appendChild(elink);
        elink.click();
        URL.revokeObjectURL(elink.href); // 释放URL对象
        document.body.removeChild(elink);
        ElMessage.success("下载成功")
      })
      .catch(() => {
        ElMessage.error("下载失败!");
      });
    }
}

引入

import { previewDownFile } from "@/utils/previewDownFile";

调用

<div class="downLoadImg svgBox">
    <el-icon size="30" @click="previewBtn(item,item.projectName+'_附件'+(index+1))">
        <Download />
    </el-icon>
</div>

vue3导入icon图标

import { Download } from '@element-plus/icons-vue';