javascriptBlob对象实现文件下载

// 下载
export function download(query,newFileName) {
  return request({
    url: '/file/download',
    method: 'get',
    responseType: 'blob',
    params: query
  }).then((res) => {
    
    let blob = res.data
    // 从response的headers中获取filename, 后端response.setHeader("Content-disposition", "attachment; filename=xxxx.docx") 设置的文件名;
    // let patt = new RegExp('filename=([^;]+\\.[^\\.;]+);*')
    // let contentDisposition = decodeURI(res.headers['content-disposition'])
    // let result = patt.exec(contentDisposition)
    // let fileName = result[1]

    //将请求的blob数据转为可下载的url地址
    let url = URL.createObjectURL(blob)
    // 创建一个下载标签<a>
    const aLink = document.createElement('a')
    aLink.href = url
    // 2.直接使用自定义文件名,设置下载文件名称
    aLink.setAttribute('download', newFileName )
    document.body.appendChild(aLink)
    // 模拟点击下载
    aLink.click()
    // 移除改下载标签
    document.body.removeChild(aLink);
  })
}

//下载
    download(row) {
      // filePath:文件路径，例如：e:\upload\
	  // fileName:文件名， 例如：a.xlsx
      let fORM = {
        filePath: row.filePath,
        fileName: row.fileName,
      };
      //下载,row.fileOriginalName是文件的原始名称，仅仅用于文件下载时起个名字而已
      download(form, row.fileOriginalName);
    }
// 由于本人使用的是阿里的oss服务，所以只需要传个文件路径回去后端，根据文件路径查询oss接口得到返回的文件流即可，例如（BufferedInputStream），在响应头设置好返回的类型即可

	// response:响应
	// filePath:文件路径，例如：e:\upload\
	// fileName:文件名， 例如：a.xlsx
   public void download(httpservletResponse response, String filePath, String fileName) {
        //待下载文件名
        response.reset();
        response.setHeader("Content-Disposition", "attachment;filename=" + fileName);
        response.setContentType("application/octet-stream");
        response.setCharacterEncoding("utf-8");
        // 创建OSSClient实例。
        OSS ossClient = new OSSClientBuilder().build(endpoint, accessKeyId, accessKeySecret);
        // ossObject包含文件所在的存储空间名称、文件名称、文件元信息以及一个输入流。
        OSSObject ossObject = ossClient.getObject(bucketName, filePath + "/" + fileName);

        BufferedInputStream in = null;
        BufferedOutputStream out = null;

        byte[] buff = new byte[1024];
        int length = 0;
        try {
            in = new BufferedInputStream(ossObject.getObjectContent());
            out = new BufferedOutputStream(response.getOutputStream());
            while ((length = in.read(buff)) != -1){
                out.write(buff,0,length);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if(out != null){
                try {
                    out.flush();
                    out.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if(in != null){
                try {
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            if (ossClient != null) {
                ossClient.shutdown();
            }
        }
    }