在WebAPI控制器下返回一个HttpResponseMessage对象，设置相应的内容即可。

Content = new StreamContent(ms)//要返回的流，任意Stream的派生类实例对象即可，注意在StreamMemory中，要把下标归到流的开始，如     ms.Seek(0, SeekOrigin.Begin);其中ms是一个StreamMemory实例对象，否则会造成读取的内容不完整

httpResponseMessage.Content.Headers.ContentType= new System.Net.Http.Headers.MediaTypeHeaderValue("application/octet-stream");//这里说明返回的是一个二进制流;

httpResponseMessage.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment") { FileName = $"{billInfoID}.xls" };//返回的文件的类型及文件名

设置的响应头中的内容，只是按一个标准设置的，其目的是方便客户端识别信息，到底是什么内容由你传的流确定。

EX:

public HttpResponseMessage ExportBill(Guid billInfoID)
     {
         Stream ms = null;
         try
         {
             ms = _HTBillInfoLogic.ExportBillInfo(billInfoID);
             ms.Seek(0, SeekOrigin.Begin);
         }
         catch(Exception e)
         {
             throw e;
         }

        HttpResponseMessage httpResponseMessage = new HttpResponseMessage(HttpStatusCode.OK)
         {
             Content = new StreamContent(ms)
         };
         httpResponseMessage.Content.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue("application/octet-stream");
         httpResponseMessage.Content.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment") { FileName = $"{billInfoID}.xls" };

        return httpResponseMessage;
     }
}

标签：WebAPI,文件,billInfoID,httpResponseMessage,Content,Headers,ms,new,下载
来源： https://www.cnblogs.com/hkfyf/p/11857897.html