使用 C#2.0 和 VIsualStudio2005
我正在尝试访问“MonitorResponseRecord”中的“DisplayName” 来自如下所示的 XML 文件:
<Magellan xsi:schemaLocation="http://tempuri.org/XMLSchema.xsd ..\Schema\Configuration.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://tempuri.org/XMLSchema.xsd">
<SchemaVersion>1.0</SchemaVersion>
<MonitorScope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" id="CleanStationChemicalManifoldFeed5" xmlns="http://tempuri.org/XMLSchema.xsd">
<PersonalSafety>
<MonitorResponseRecord Enabled="true" DisplayName="ChemicalManifoldFeed5ControllerFault">
<ExpressionMonitor>
<Expression>(ChemicalManifold.Feed5.DispenseValve = Open) and ((ChemicalManifold.Feed5.ViolatedRegion = HighProcess) or (ChemicalManifold.Feed5.ViolatedRegion = LowProcess) or (ChemicalManifold.Feed5.ViolatedRegion = Minimum))</Expression>
<TestInterval>0.1</TestInterval>
<MinimumTimeBetweenResponses>5</MinimumTimeBetweenResponses>
</ExpressionMonitor>
<Response>
<PostAlarm>
<AlarmName>ChemicalManifold_Feed5_ControllerFault</AlarmName>
<Parameter1 />
<Parameter2>Alarm Region = {ChemicalManifold.Feed5.ViolatedRegion}</Parameter2>
<Parameter3>{RecipeName}-{StepName}</Parameter3>
<Parameter4>FlowSetpoint = {ChemicalManifold.Feed5.Setpoint}-LPM, ActualFlow = {ChemicalManifold.Feed5.FlowMeter}-LPM</Parameter4>
</PostAlarm>
<ResponseEvent>
<TargetResource />
<Event>PA</Event>
<Reason>ChemicalSupply</Reason>
</ResponseEvent>
</Response>
</MonitorResponseRecord>
</PersonalSafety>
<PersonalSafety>
<MonitorResponseRecord Enabled="true" DisplayName = "PressureValveFailure">
...
...
...and soon
我当前的 C# 尝试如下,但是当我尝试 XmlDocument.Load("");
XmlDocument doc = new XmlDocument();
doc.Load("../UMC0009.Configuration.Root.xml");
string attrVal = doc.SelectSingleNode("MonitorResponseRecord/@DisplayName").Value;
BUUUUT 不工作:/有什么帮助吗?
更新:
我收到的异常如下,发生在 doc.Load("...") 行:
{“需要命名空间管理器或 XsltContext。此查询具有前缀、变量或用户定义的函数。”} System.Exception {System.Xml.XPath.XPathException}
最佳答案
您的 XPath 查询将相对于文档根目录:
doc.SelectSingleNode("MonitorResponseRecord/@DisplayName")
要使其在文档中的任何地方搜索,请在其前面加上双斜杠:
doc.SelectSingleNode("//MonitorResponseRecord/@DisplayName")
如果这仍然不起作用,我将在去除两个根节点上的所有命名空间声明后尝试上面的示例。
否则,对于命名空间声明,您可能会发现需要定义 XML 命名空间映射并在 XPath 中使用前缀,例如:
XmlNamespaceManager nsmgr = new XmlNamespaceManager(doc.NameTable);
nsmgr.AddNamespace("x", "http://tempuri.org/XMLSchema.xsd");
doc.SelectSingleNode("//x:MonitorResponseRecord/@DisplayName")
关于C#:读取 XML 属性,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/10920656/