一、根据网络路径把文件保存成byte[]返回给前端

项目采用的是前后端分离的模式，后端使用ASP.NET Core WebAPI方式，将文件流返回给前端。

/// <summary>
/// 根据网络路径把文件保存成byte[]
/// </summary>
/// <param name="filePath"></param>
public byte[] UrlToByte(string filePath)
{
    HttpWebRequest req = (HttpWebRequest)HttpWebRequest.Create(filePath);
    req.Method = "GET";
    using (WebResponse wr = req.GetResponse())
    {
        StreamReader responseStream = new StreamReader(wr.GetResponseStream(), Encoding.UTF8);
        int length = (int)wr.ContentLength;
        byte[] bs = new byte[length];
 
        HttpWebResponse response = wr as HttpWebResponse;
        Stream stream = response.GetResponseStream();
 
        //读取到内存
        MemoryStream stmMemory = new MemoryStream();
        byte[] buffer1 = new byte[length];
        int i;
        while ((i = stream.Read(buffer1, 0, buffer1.Length)) > 0)
        {
            stmMemory.Write(buffer1, 0, i);
        }
        byte[] arraryByte = stmMemory.ToArray();
        stmMemory.Close();
        return arraryByte;
    }
}

二、解决前端无法获得fileName

前端采用的是Vue技术栈，采用的是axios调用后端接口。前端无法获得fileName需要修改后端ASP.NET Core WebAPI项目中的【Startup.cs】文件。

 修改ConfigureServices方法中的AddCors。

代码示例：

 .WithExposedHeaders("Content-Disposition");//应前端要求暴露Content-Disposition