[英]remove data from XML file using c#?
我實現了一個包含以下數據的XML文檔
<TrafficPattern>
<WayPoint>
<Radial>001</Radial>
<Distance>0.36</Distance>
<Latitude>
<Degrees>48</Degrees>
<Minutes>31.7363644</Minutes>
</Latitude>
<Longitude>
<Degrees>11</Degrees>
<Minutes>57.53425</Minutes>
</Longitude>
</WayPoint>
<WayPoint>
<Radial>090</Radial>
<Distance>0.56</Distance>
<Latitude>
<Degrees>48</Degrees>
<Minutes>31.7363644</Minutes>
</Latitude>
<Longitude>
<Degrees>11</Degrees>
<Minutes>57.53425</Minutes>
</Longitude>
</WayPoint>
<WayPoint>
<Radial>240</Radial>
<Distance>0.56</Distance>
<Latitude>
<Degrees>48</Degrees>
<Minutes>31.7363644</Minutes></Latitude>
<Longitude>
<Degrees>11</Degrees>
<Minutes>57.53425</Minutes></Longitude>
</WayPoint>
<WayPoint>
<Radial>346</Radial>
<Distance>0.56</Distance>
<Latitude>
<Degrees>48</Degrees>
<Minutes>31.7363644</Minutes></Latitude>
<Longitude>
<Degrees>11</Degrees>
<Minutes>57.53425</Minutes></Longitude>
</WayPoint>
</TrafficPattern>
我使用XMLDocument
編寫了上述XML文件。
現在,我想通過單擊按鈕從XML文件中刪除航點。
有人可以建議我一種如何使用XMLDocument
刪除它的方法嗎?
我相信您想使用RemoveChild API。 您還可以使用SelectSingleNode或SelectNodes API查找要刪除的節點,移動到其父節點並刪除它們。
您需要使用XmlNode.RemoveChild
方法,但是請注意,僅當將其應用於您要刪除的節點的父節點時,此方法才有效,否則您將得到異常:
要刪除的節點不是該節點的子節點
下面的RemoveNode
方法基於一個簡單的XML示例 。
public sealed class TestXmlNodeRemoval
{
public static void RemoveNode()
{
var xmlDocument = new XmlDocument();
var xmlTrafficPattern = xmlDocument.CreateElement("TrafficPattern");
xmlDocument.AppendChild(xmlTrafficPattern);
xmlTrafficPattern.AppendChild(CreateWayPoint(xmlDocument,
"001", "0.36", "48", "31.7363644", "11", "57.53425"));
xmlTrafficPattern.AppendChild(CreateWayPoint(xmlDocument,
"090", "0.56", "48", "31.7363644", "11", "57.53425"));
xmlTrafficPattern.AppendChild(CreateWayPoint(xmlDocument,
"240", "0.56", "48", "31.7363644", "11", "57.53425"));
xmlTrafficPattern.AppendChild(CreateWayPoint(xmlDocument,
"346", "0.56", "48", "31.7363644", "11", "57.53425"));
Console.WriteLine(@"Original traffic pattern:");
DisplayXmlDocument(xmlDocument);
// create an arbitrary criterion to remove an element
const string radialToRemove = @"090";
Console.WriteLine(@"Remove node with radial=" + radialToRemove);
if (xmlDocument.DocumentElement != null)
{
for (var i = 0; i < xmlDocument.DocumentElement.ChildNodes.Count; ++i)
{
var radial =
xmlDocument.DocumentElement.ChildNodes[i].SelectSingleNode("Radial");
if (radial == null || (radial.InnerText != radialToRemove))
{
continue;
}
var nodeToRemove = xmlDocument.DocumentElement.ChildNodes[i];
// note that you need to remove node from the Parent
if (nodeToRemove.ParentNode != null)
{
nodeToRemove.ParentNode.RemoveChild(nodeToRemove);
}
break;
}
}
Console.WriteLine(@"New traffic pattern:");
DisplayXmlDocument(xmlDocument);
}
}
上面的方法創建以下輸出:
原始流量模式:
徑向:001,距離:0.36,緯度:(48,31.7363644),經度:(11,57.53425)
徑向:090,距離:0.56,緯度:(48,31.7363644),經度:(11,57.53425)
徑向:240,距離:0.56,緯度:(48,31.7363644),經度:(11,57.53425)
徑向:346,距離:0.56,緯度:(48,31.7363644),經度:(11,57.53425)
用radius = 090刪除節點
新的流量模式:
徑向:001,距離:0.36,緯度:(48,31.7363644),經度:(11,57.53425)
徑向:240,距離:0.56,緯度:(48,31.7363644),經度:(11,57.53425)
徑向:346,距離:0.56,緯度:(48,31.7363644),經度:(11,57.53425)
我使用的支持方法復制如下。
第一種方法創建了一個航路點,因此上面的代碼並不那么混亂。 為了簡單起見,所有內容都是一個string
,但我可能會選擇更好的參數類型
private static XmlElement CreateWayPoint(XmlDocument xmlDoc,
string radial,
string distance,
string latDegrees,
string latMinutes,
string longDegrees,
string longMinutes)
{
var xmlWayPoint = xmlDoc.CreateElement("WayPoint");
var xmlRadial = xmlDoc.CreateElement("Radial");
xmlRadial.InnerText = radial;
xmlWayPoint.AppendChild(xmlRadial);
var xmlDistance = xmlDoc.CreateElement("Distance");
xmlDistance.InnerText = distance;
xmlWayPoint.AppendChild(xmlDistance);
var xmlLatitude = xmlDoc.CreateElement("Latitude");
var xmlLatDegrees = xmlDoc.CreateElement("Degrees");
xmlLatDegrees.InnerText = latDegrees;
xmlLatitude.AppendChild(xmlLatDegrees);
var xmlLatMinutes = xmlDoc.CreateElement("Minutes");
xmlLatMinutes.InnerText = latMinutes;
xmlLatitude.AppendChild(xmlLatMinutes);
xmlWayPoint.AppendChild(xmlLatitude);
var xmlLongitude = xmlDoc.CreateElement("Longitude");
var xmlLongDegrees = xmlDoc.CreateElement("Degrees");
xmlLongDegrees.InnerText = longDegrees;
xmlLongitude.AppendChild(xmlLongDegrees);
var xmlLongMinutes = xmlDoc.CreateElement("Minutes");
xmlLongMinutes.InnerText = longMinutes;
xmlLongitude.AppendChild(xmlLongMinutes);
xmlWayPoint.AppendChild(xmlLongitude);
return xmlWayPoint;
}
並且此方法顯示XML文檔:
private static void DisplayXmlDocument(XmlNode xmlDoc)
{
var wayPoints = xmlDoc.SelectNodes("TrafficPattern/WayPoint");
if (wayPoints == null)
{
return;
}
foreach (XmlNode wayPoint in wayPoints)
{
var radial = wayPoint.SelectSingleNode("Radial");
var distance = wayPoint.SelectSingleNode("Distance");
var latitudeDegrees = wayPoint.SelectSingleNode("Latitude/Degrees");
var latitudeMinutes = wayPoint.SelectSingleNode("Latitude/Minutes");
var longitudeDegrees = wayPoint.SelectSingleNode("Longitude/Degrees");
var longitudeMinutes = wayPoint.SelectSingleNode("Longitude/Minutes");
if (radial != null &&
distance != null &&
latitudeDegrees != null &&
latitudeMinutes != null &&
longitudeDegrees != null &&
longitudeMinutes != null)
{
Console.WriteLine(string.Format("Radial:{0},
Distance:{1},
Latitude:({2}, {3}),
Longitude:({4}, {5})",
radial.InnerText,
distance.InnerText,
latitudeDegrees.InnerText,
latitudeMinutes.InnerText,
longitudeDegrees.InnerText,
longitudeMinutes.InnerText));
}
}
}
您只能使用C# 來執行此操作,但是使用XSLT可以輕松完成,而且.NET內置了出色的XSLT處理器 。XSLT是一種開放標准,專門設計用於將XML轉換為另一種XML格式(或HTML或文本)。
輸入XSLT如下所示,將其另存為removeelement.xslt:
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="1.0">
<xsl:param name="Radial"/>
<xsl:output indent="yes" />
<xsl:template match="TrafficPattern">
<xsl:copy>
<xsl:copy-of select="@*"/>
<xsl:apply-templates select="WayPoint[not(Radial = $Radial)]" />
</xsl:copy>
</xsl:template>
<xsl:template match="node()|@*">
<xsl:copy>
<xsl:apply-templates select="node() | @*" />
</xsl:copy>
</xsl:template>
</xsl:stylesheet>
通過C#在您的輸入上調用它很容易。 XSLT當前包含一個參數Radial
,但是您可以將其擴展為選擇要刪除的節點所需的任何內容,代碼本身就可以說明問題。 這是一個使用輸入XML(稱為input.xml)調用XSLT的示例:
// Load the xslt stylesheet:
XslCompiledTransform xslt = new XslCompiledTransform();
xslt.Load("removeelement.xslt");
// Create the XsltArgumentList with param
XsltArgumentList xslArg = new XsltArgumentList();
xslArg.AddParam("Radial", "", "090");
// do the transformation on your input (can also use Stream or TextWriter)
using (XmlWriter w = XmlWriter.Create("output-with-removed-element.xml"))
{
xslt.Transform("input.xml", xslArg, w);
}
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