vue实现图片上传数据库（vue.js根据图片url进行图片下载）

<a @click="downCom" >
                下载执照
                <i class="icon-down"></i>
              </a>

downCom() {
      let that = this;
      this.$http.files().then(res => {
        let hreLocal="";
        hreLocal = res.data.data.url;
        this.downloadByBlob(hreLocal,"pic")

      });
    },

downloadByBlob(url,name) {
    let image = new Image()
    image.setAttribute('crossOrigin', 'anonymous')
    image.src = url
    image.onload = () => {
      let canvas = document.createElement('canvas')
      canvas.width = image.width
      canvas.height = image.height
      let ctx = canvas.getContext('2d')
      ctx.drawImage(image, 0, 0, image.width, image.height)
      canvas.toBlob((blob) => {
        let url = URL.createObjectURL(blob)
        download(url,name)
        // 用完释放URL对象
        URL.revokeObjectURL(url)
      })
    }
  },

function download(href, name) {
  let eleLink = document.createElement('a')
  eleLink.download = name
  eleLink.href = href
  eleLink.click()
  eleLink.remove()
}