downloadFile() {
      let selectIDs = []
      selectIDs = JSON.parse(JSON.stringify(this.newListArr))
      /*post(exportCustomMItemDataWithLine, {
        selectIDs
      }).then(res => {
        let data = res
        if (!data) {
          return
        }
        const url = window.URL.createObjectURL(new Blob([data]))
        let link = document.createElement('a')
        let myDate = new Date()

        link.style.display = 'none'
        link.href = url
        link.setAttribute('download', '数据查询导出' + date2md(myDate) + '.xls')
        document.body.appendChild(link)
        link.click()
        document.body.removeChild(link) //下载完成移除元素
        window.URL.revokeObjectURL(url) //释放掉blob对象
      })*/
      this.params.selectIDs = selectIDs
      axios({
        method: 'post',
        url: exportCustomMItemDataWithLine,
        data: this.params,
        responseType: 'blob'
      }).then(res => {
        if (!res) {
          return
        }
        const blob = new Blob([res.data], { type: 'application/vnd.ms-excel' })
        const fileName = res.headers['content-disposition'].split('=')[1]
        let url = ''
        let isBlob = false
        const errMsg = '下载出错，文件数据无法识别!'
        let data = blob
        if (data instanceof Blob) {
          isBlob = true
          url = window.URL.createObjectURL(data)
        } else if (typeof data == 'string') {
          // base64编码
          url = data
        } else {
          Message.error(errMsg)
          return
        }

        if ('download' in document.createElement('a')) {
          // 非IE下载
          const tmpLink = document.createElement('a')
          tmpLink.download = fileName || ''
          tmpLink.style.display = 'none'
          tmpLink.href = url
          document.body.appendChild(tmpLink)
          tmpLink.click()
          window.URL.revokeObjectURL(tmpLink.href)
          document.body.removeChild(tmpLink)
        } else {
          // IE10+下载
          if (isBlob) {
            window.navigator.msSaveBlob(data, fileName)
          } else {
            console.log(errMsg)
            return
          }
        }
      })
      this.selectCheckbox = []
      this.tableHeadInfo.forEach(item => {
        item.checked = false
      })
      this.$refs.multipleTable.clearSelection()
      this.selectIDs = []
    },

      axios({
        method: 'post',
        url: exportCustomMItemDataWithLine,
        data: this.params,
        responseType: 'blob'
      }).then(res => {
        if (!res) {
          return
        }
        const blob = new Blob([res.data], { type: 'application/vnd.ms-excel' })
        const fileName = res.headers['content-disposition'].split('=')[1]
        let url = ''
        let isBlob = false
        const errMsg = '下载出错，文件数据无法识别!'
        let data = blob
        if (data instanceof Blob) {
          isBlob = true
          url = window.URL.createObjectURL(data)
        } else if (typeof data == 'string') {
          // base64编码
          url = data
        } else {
          Message.error(errMsg)
          return
        }

        if ('download' in document.createElement('a')) {
          // 非IE下载
          const tmpLink = document.createElement('a')
          tmpLink.download = fileName || ''
          tmpLink.style.display = 'none'
          tmpLink.href = url
          document.body.appendChild(tmpLink)
          tmpLink.click()
          window.URL.revokeObjectURL(tmpLink.href)
          document.body.removeChild(tmpLink)
        } else {
          // IE10+下载
          if (isBlob) {
            window.navigator.msSaveBlob(data, fileName)
          } else {
            console.log(errMsg)
            return
          }
        }
      })