将大量数据导出到字符串(csv 格式)时,出现 OutOfMemoryException。解决这个问题的最佳方法是什么?字符串返回到 Flex 应用程序。
我要做的是将 csv 导出到服务器磁盘并将 URL 返回给 Flex。像这样,我可以刷新写入磁盘的流。
更新:
使用 StringBuilder 构建字符串:
StringBuilder stringbuilder = new StringBuilder();
string delimiter = ";";
bool showUserData = true;
// Get the data from the sessionwarehouse
List<DwhSessionDto> collection
=_dwhSessionRepository.GetByTreeStructureId(treeStructureId);
// ADD THE HEADERS
stringbuilder.Append("UserId" + delimiter);
if (showUserData)
{
stringbuilder.Append("FirstName" + delimiter);
stringbuilder.Append("LastName" + delimiter);
}
stringbuilder.Append("SessionId" + delimiter);
stringbuilder.Append("TreeStructureId" + delimiter);
stringbuilder.Append("Name" + delimiter);
stringbuilder.Append("Score" + delimiter);
stringbuilder.Append("MaximumScore" + delimiter);
stringbuilder.Append("MinimumScore" + delimiter);
stringbuilder.Append("ReducedScore" + delimiter);
stringbuilder.Append("ReducedMaximumScore" + delimiter);
stringbuilder.Append("Duration" + delimiter);
stringbuilder.AppendLine("Category" + delimiter);
foreach (var dwhSessionDto in collection)
{
stringbuilder.Append(
getPackageItemsInCsvFromDwhSessionDto(
dwhSessionDto, delimiter, showUserData));
}
return stringbuilder.ToString();
字符串被发送回 Flex,如下所示:
var contentType = "text/csv";
string result = exportSessionService.ExportPackage(treeStructureId);
// Write the export to the response
_context.Response.ContentType = contentType;
_context.Response.AddHeader("content-disposition",
String.Format("attachment; filename={0}", treeStructureId + ".csv"));
// do not Omit the Vary star so the caching at the client side will be disabled
_context.Response.Cache.SetOmitVaryStar(false);
_context.Response.Cache.SetCacheability(HttpCacheability.NoCache);
if (!String.IsNullOrEmpty(result))
{
_context.Response.Output.Write(result);
_context.Response.Output.Close();
}
else
{
_context.Response.Output.Write("No logs");
}