将后台的二进制流进行下载

downloadFile(data) {

    if (!data) { return } 

    let url = window.URL.createObjectURL(new Blob([data])); 

    let link = document.createElement('a'); 

    link.style.display = 'none'; 

    link.href = url; link.setAttribute('download', '导出数据.csv');

    document.body.appendChild(link); link.click()

}