当看到带有MemoryStream和XmlTextWriter的特定模式时,Visual Studio 2010 Ultimate中的“运行代码分析”命令将返回警告.
这是警告:
Warning 7 CA2202 : Microsoft.Usage :
Object ‘ms’ can be disposed more than
once in method
‘KinteWritePages.GetXPathDocument(DbConnection)’.
To avoid generating a
System.ObjectDisposedException you
should not call Dispose more than one
time on an object.: Lines:
421 C:\Visual Studio
2010\Projects\Songhay.DataAccess.KinteWritePages\KinteWritePages.cs 421 Songhay.DataAccess.KinteWritePages
形式如下:
static XPathDocument GetXPathDocument(DbConnection connection)
{
XPathDocument xpDoc = null;
var ms = new MemoryStream();
try
{
using(XmlTextWriter writer = new XmlTextWriter(ms, Encoding.UTF8))
{
using(DbDataReader reader = CommonReader.GetReader(connection, Resources.KinteRssSql))
{
writer.WriteStartDocument();
writer.WriteStartElement("data");
do
{
while(reader.Read())
{
writer.WriteStartElement("item");
for(int i = 0; i < reader.FieldCount; i++)
{
writer.WriteRaw(String.Format("<{0}>{1}</{0}>", reader.GetName(i), reader[i].ToString()));
}
writer.WriteFullEndElement();
}
} while(reader.NextResult());
writer.WriteFullEndElement();
writer.WriteEndDocument();
writer.Flush();
ms.Position = 0;
xpDoc = new XPathDocument(ms);
}
}
}
finally
{
ms.Dispose();
}
return xpDoc;
}
此表单会产生相同类型的警告:
XPathDocument xpDoc = null;
using(var ms = new MemoryStream())
{
using(XmlTextWriter writer = new XmlTextWriter(ms, Encoding.UTF8))
{
using(DbDataReader reader = CommonReader.GetReader(connection, Resources.KinteRssSql))
{
//...
}
}
}
return xpDoc;
顺便说一句,以下表格会产生另一个警告:
XPathDocument xpDoc = null;
var ms = new MemoryStream();
using(XmlTextWriter writer = new XmlTextWriter(ms, Encoding.UTF8))
{
using(DbDataReader reader = CommonReader.GetReader(connection, Resources.KinteRssSql))
{
//...
}
}
return xpDoc;
上面产生警告:
Warning 7 CA2000 :
Microsoft.Reliability : In method
‘KinteWritePages.GetXPathDocument(DbConnection)’,
object ‘ms’ is not disposed along all
exception paths. Call
System.IDisposable.Dispose on object
‘ms’ before all references to it are
out of scope. C:\Visual Studio
2010\Projects\Songhay.DataAccess.KinteWritePages\KinteWritePages.cs 383 Songhay.DataAccess.KinteWritePages
除了以下内容,我还有哪些选择?
>禁止警告CA2202.
> Supress警告CA2000,并希望
微软正在处置
MemoryStream(因为
Reflector没有显示源代码.
>重写我的旧代码以识别
很棒的XDocument和LINQ
XML.
解决方法:
首先,永远不要使用新的XmlTextWriter().从.NET 2.0开始不推荐使用.请改用XmlWriter.Create().
其次,对ms的分配应在using块中:
using (var ms = new MemoryStream())
{
using (var writer = XmlWriter.Create(ms))
{
// ...
}
}
我相信警告是正确的.可以在处理XmlTextWriter时处理MemoryStream,然后在“ finally”块中再次处理.
标签:dispose,linq,xml,c 来源: https://codeday.me/bug/20191023/1914487.html
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