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, , (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();

    $.ajax({

        url: '/Login/DownLoad',

        type: 'post',

        data: {id : id},

        success: function (data) {

            layer.closeAll('loading');

            if (data.success) {

                layer.open({

                    title: "信息",

                    type: ,

                    area: ['100%', '100%'],

                    content: data.pdfBase64String

                });

            } else {

                layer.msg(data.msg, { icon: , time:  });

            }

        }, error: function () {

            layer.closeAll('loading');

            layer.msg('网络错误，请稍后重试', { icon: , time:  });

        }

    })

}

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