在asp.net c#中提供大量记录的XML文件供下载

本文关键字：记录 XML 文件 下载 net asp | 更新日期: 2023-09-27 18:12:21

我需要提供大约60万条记录的xml文件下载(数据可能会增加)，但不允许将文件保存在磁盘上。我面临的问题是直接编写xml流&然后提供下载，所以我首先在磁盘上创建了XML文件&向它写入数据，并尝试用眼睛读取数据& &;提供下载，然后从磁盘上删除文件。但是得到"系统"。outofmemoryexception"Byte[] b = File.ReadAllBytes(filepath);".

下面是我的代码: 
string name = string.Format("{0:yyyyMMddHHmmss}", DateTime.Now);
string filename = "TestFile.xml";
string filepath = ConfigurationManager.AppSettings["XmlFiles"] + "''" + filename;

DataTable dataTable = dsData.Tables[0];             
FileStream fs =new FileStream(filepath, FileMode.Create);
XmlWriterSettings xws = new XmlWriterSettings { OmitXmlDeclaration = true };
using (XmlWriter xmlWriter = XmlWriter.Create(fs,xws))
{
  xmlWriter.WriteStartElement("root");
  foreach (DataRow dataRow in dataTable.Rows)
  {
    xmlWriter.WriteStartElement("datanode");
    foreach (DataColumn dataColumn in dataTable.Columns)
    {
     xmlWriter.WriteElementString(dataColumn.ColumnName.Replace("'n'r", " ")
                                  .Replace("'n", " ").Replace("'r", " "), Convert.ToString(dataRow[dataColumn]).Replace("'n'r", " ").Replace("'n", " ").Replace("'r", " "));
                        }
         xmlWriter.WriteEndElement();
     }
     xmlWriter.WriteEndElement();
     xmlWriter.Flush();
     xmlWriter.Close();
   }
   fs.Close();
   Byte[] b = File.ReadAllBytes(filepath);                
   if (File.Exists(filepath))
      File.Delete(filepath);
string s = string.Format("{0:yyyyMMddHHmmss}", DateTime.Now);
HttpContext.Current.Response.ContentType = "application/xml";
HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.UTF8;
HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment; filename=" + s + ".xml" + "");
HttpContext.Current.Response.BinaryWrite(b);
HttpContext.Current.Response.End();

有其他方法来处理大量的记录吗?

在asp.net c#中提供大量记录的XML文件供下载

您可以直接将XmlWriter连接到Response OutputStream，而不需要中间文件。通过将BufferOutput设置为false，可以防止完整的响应在发送到客户端之前被服务器端缓冲。

请注意，多个Replace语句将导致额外的内存压力/需要GC-ed更多字符串。

string name = string.Format("attachment; filename={0:yyyyMMddHHmmss}.xml", DateTime.Now);
HttpContext.Current.Response.ContentType = "application/xml";
HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.UTF8;
HttpContext.Current.Response.BufferOutput = false; //start streaming immideately
HttpContext.Current.Response.AppendHeader("Content-Disposition", name);
DataTable dataTable = dsData.Tables[0];             
XmlWriterSettings xws = new XmlWriterSettings { OmitXmlDeclaration = true };
using (XmlWriter xmlWriter = XmlWriter.Create(
         HttpContext.Current.Response.OutputStream,  // The OutputStream of the HttpResponse
         xws))
{
  xmlWriter.WriteStartElement("root");
  var cleanedColNames = new Dictionary<DataColumn, string>();
  foreach (DataColumn dataColumn in dataTable.Columns)
  {
      cleanedColNames.Add(dataColumn, 
          dataColumn.ColumnName.Replace("'n'r", " ")
                               .Replace("'n", " ")
                               .Replace("'r", " "));
  }
  foreach (DataRow dataRow in dataTable.Rows)
  {
    xmlWriter.WriteStartElement("datanode");
    foreach (DataColumn dataColumn in dataTable.Columns)
    {
         xmlWriter.WriteElementString(
             cleanedColNames[dataColumn],  
             Convert.ToString(dataRow[dataColumn]).Replace("'n'r", " ")
                                                  .Replace("'n", " ")
                                                  .Replace("'r", " "));
                        }
         xmlWriter.WriteEndElement();
     }
     xmlWriter.WriteEndElement();
     xmlWriter.Flush();
     xmlWriter.Close();
   }
HttpContext.Current.Response.End();
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