c# - Disposable：MemoryStream.Capacity 在生成 PDF 文件时抛出 System.ObjectDisposedException 异常

Question

我Disposable pattern在生成 PDF 文件时使用。使用以下代码：

public partial class WriteNotes : System.Web.UI.Page
{
     ...
     protected override void Render(System.Web.UI.HtmlTextWriter writer)
     {
        ...
        using (System.IO.MemoryStream printStream = new System.IO.MemoryStream())
        using (System.IO.StreamWriter printStreamWriter = new System.IO.StreamWriter(printStream))
        using (System.Web.UI.HtmlTextWriter printWriter = new System.Web.UI.HtmlTextWriter(printStreamWriter))
        {
            base.Render(printWriter);
            printWriter.Flush();
            using (System.IO.StreamReader myStreamReader = new System.IO.StreamReader(printStream))
            {
               myStreamReader.BaseStream.Position = 0;
               Document pdfDocument = pdfConverter.GetPdfDocumentObjectFromHtmlStream(myStreamReader.BaseStream, System.Text.Encoding.Default, HttpContext.Current.Request.Url.ToString().Replace(HttpContext.Current.Request.Url.PathAndQuery, "/"));
               HttpContext.Current.Response.Clear();
               HttpContext.Current.Response.ContentType = "application/pdf";
               pdfDocument.Save(HttpContext.Current.Response.OutputStream);
               HttpContext.Current.Response.Flush();
               HttpContext.Current.Response.End();
            }
        }
    }
    ...
}

执行后：

Document pdfDocument = pdfConverter.GetPdfDocumentObjectFromHtmlStream(myStreamReader.BaseStream,   System.Text.Encoding.Default,HttpContext.Current.Request.Url.ToString().Replace(HttpContext.Current.Request.Url.PathAndQuery, "/"));

通过 MemoryStream 的属性时，我观察到以下内容：

Capacity: 'printStream.Capacity' threw an exception of type 'System.ObjectDisposedException'
Length: 'printStream.Length' threw an exception of type 'System.ObjectDisposedException'
Position: 'printStream.Position' threw an exception of type 'System.ObjectDisposedException'

代码可能有什么问题？

Answer 1

也许编译器没有正确地将 using 块括起来。如果您明确地将 using 语句括起来，您是否看到同样的问题？

编辑：由于缺乏代表，无法发表评论:(。

Answer 2

问题是，您在移动到位置 = 0 之前确实刷新了流。尝试不刷新，只需注释掉printWriter.Flush().