后台PDF返回Base64，前台接收预览

 string base64String = "";
byte[] buffer=null;
                    using (FileStream fs = new FileStream(path, FileMode.Open))
                    {
                        long fileSize = fs.Length;
                       buffer = new byte[(int)fileSize];
                        fs.Read(buffer, 0, (int)fs.Length);
                        base64String = Convert.ToBase64String(buffer);
                    }
                    //生成base64后删除原文件
                    if (System.IO.File.Exists(newPdf))
                    {
                        System.IO.File.Delete(newPdf);
                    }
　　　　　　　　　　　　//return File(buffer, "application/ms-pdf", fileName);//返回文件流，前台接收可以直接下载
                    return Json(new { success = true, pdfBase64String = "data:application/pdf;base64," + base64String });

function lookInfo(id) {
    layer.load(1);
    $.ajax({
        url: ‘/Login/DownLoad‘,
        type: ‘post‘,
        data: {id : id},
        success: function (data) {
            layer.closeAll(‘loading‘);
            if (data.success) {
                layer.open({
                    title: "信息",
                    type: 2,
                    area: [‘100%‘, ‘100%‘],
                    content: data.pdfBase64String
                });
            } else {
                layer.msg(data.msg, { icon: 5, time: 2000 });
            }
        }, error: function () {
            layer.closeAll(‘loading‘);
            layer.msg(‘网络错误，请稍后重试‘, { icon: 5, time: 2000 });
        }
    })
   
}

  window.open("/Login/DownLoad?id=" + id;