C#下使用XmlDocument详解
转载:https://blog.csdn.net/mpegfour/article/details/78550228
XML在开发中作为文件存储格式、数据交换的协议用的非常普遍,各个编程语言有都支持。W3C也制定了XML DOM的标准。在这里主要介绍下.Net中的XmlDocument,包括xml读取和写入等功能。
一、Xml的加载读取
1、数据等准备
Xml测试数据:
<?xml version="1.0" encoding="UTF-8"?>
-<CameraGroup WKT="UNKNOWNCS["unnamed"]">
<Camera duration="5" comment="" roll="-4.29374881997575E-14" tilt="-15.333841267255" heading="-50.5252574662688" z="770.962000000316" y="24483.2877865981" x="10533.2696556843" Picture="b22d08c9-59f2-4b21-a254-d7133eb1b7bb.jpg" Name="初始界面"/>
<Camera duration="5" comment="" roll="-9.54166404439055E-15" tilt="-12.2364039278614" heading="-71.2583141496969" z="524.34103072128" y="24767.3735196134" x="10161.8880158652" Picture="6c7e6098-6064-401c-93c0-dce573f86b5d.jpg" Name="分区1"/>
</CameraGroup>
读取的数据,我们定义了一个实体类LocationCamera,用来保存Xml解析后的数据:
public class LocationCamera
{
public LocationCamera()
{
}
private string name;
public string Name
{
get { return name; }
set { name = value ; }
}
private int duration;
public int Duration
{
get { return duration; }
set { duration = value ; }
}
private double roll; //="-4.29374881997575E-14"
public double Roll
{
get { return roll; }
set { roll = value ; }
}
private double tilt; //="-15.333841267255"
public double Tilt
{
get { return tilt; }
set { tilt = value ; }
}
private double heading; //="-50.5252574662688"
public double Heading
{
get { return heading; }
set { heading = value ; }
}
private double z; //="770.962000000316"
public double Z
{
get { return z; }
set { z = value ; }
}
private double y; //="24483.2877865981"
public double Y
{
get { return y; }
set { y = value ; }
}
private double x; //="10533.2696556843"
public double X
{
get { return x; }
set { x = value ; }
}
}
2、Xml读取
a、Xml加载
Xml是个标准,对于用该标准存取的内容可以来自文件、内部串或者二进制流,所以对于Xml的加载有这么几种:
加载xml文件
Load(string filename);
加载xml流
Load(Stream inStream);
加载xml字符串
LoadXml(string xml);
b、Xml元素读取
XmlDocument支持使用xpath表达式选择文档中节点,方法:
SelectNodes(String expression)
SelectSingleNode(string expression)
SelectNodes 返回符合expression表达式的所有元素,返回值为XmlNodeList,比如本例子是通过XmlNodeList nodelist = xmlDoc.SelectNodes("/CameraGroup/Camera");获取所有的Camera节点。
SelectSingleNode只返回第一个符合expression表达式的节点,如果没有返回null值。
返回的XmlNodeList,我们可以通过循环读取,对于单个XmlNode,我们通过Attributes获取属性值。
读取的完整代码如下:
public static Hashtable getCameraXml( string path)
{
Hashtable hashtable = new Hashtable ();
if ( File .Exists(path))
{
XmlDocument xmlDoc = new XmlDocument ();
//xml来自本地文件
xmlDoc.Load(path);
if (xmlDoc != null )
{
//获取所有的Camera节点
XmlNodeList nodelist = xmlDoc.SelectNodes( "/CameraGroup/Camera" );
//遍历节点获取节点属性,并保存在 LocationCamera类中
foreach ( XmlNode node in nodelist)
{
LocationCamera locationCamera = new LocationCamera ();
locationCamera.Name=node.Attributes[ "Name" ].Value.ToString();
locationCamera.Roll=System. Convert .ToDouble(node.Attributes[ "roll" ].Value.ToString());
locationCamera.Tilt = System. Convert .ToDouble(node.Attributes[ "tilt" ].Value.ToString());
locationCamera.Heading = System. Convert .ToDouble(node.Attributes[ "heading" ].Value.ToString());
locationCamera.X = System. Convert .ToDouble(node.Attributes[ "x" ].Value.ToString());
locationCamera.Y = System. Convert .ToDouble(node.Attributes[ "y" ].Value.ToString());
locationCamera.Z = System. Convert .ToDouble(node.Attributes[ "z" ].Value.ToString());
hashtable.Add(locationCamera.Name, locationCamera);
Console .WriteLine(node.OuterXml);
}
return hashtable;
}
}
return null ;
}
SelectNodes、SelectSingleNode也可以读取指定属性值的节点,比如XmlNodeList nodelist = xmlDoc.SelectNodes("/CameraGroup/Camera[@Name='分区1']");表示读取Name为"分区1"的所有节点。
二、Xml创建的写入
写入内容主要包括xml声明、根节点、子节点及节点属性。生成的Xml文件和代码如下:
<?xml version="1.0"?>
-<CameraGroup WKT="UNKNOWNCS["unnamed"">
<Camera X="112.42342" Name="分区1"/>
</CameraGroup>
写入的代码:
public static void writeCameraXml( string path)
{
XmlDocument xmlDoc = new XmlDocument ();
//创建Xml声明部分,即<?xml version="1.0" encoding="utf-8" ?>
xmlDoc.CreateXmlDeclaration( "1.0" , "utf-8" , "yes" );
//创建CameraGroup根节点
XmlNode rootNode = xmlDoc.CreateElement( "CameraGroup" );
//创建WKT属性
XmlAttribute wktAttribute = xmlDoc.CreateAttribute( "WKT" );
wktAttribute.Value = "UNKNOWNCS[\"unnamed\"" ;
//为根节点添加属性
rootNode.Attributes.Append(wktAttribute);
//创建Camera子节点
XmlNode cameraNode = xmlDoc.CreateElement( "Camera" );
//创建Name属性
XmlAttribute nameAttribute = xmlDoc.CreateAttribute( "Name" );
nameAttribute.Value = "分区1" ;
//为Camera添加属性
cameraNode.Attributes.Append(nameAttribute);
//创建X属性
XmlAttribute xAttribute = xmlDoc.CreateAttribute( "X" );
xAttribute.Value = "112.42342" ;
//为Camera添加X属性
cameraNode.Attributes.Append(xAttribute);
//为根节点CameraGroup添加Camera子节点
rootNode.AppendChild(cameraNode);
//为Xml文档添加根元素
xmlDoc.AppendChild(rootNode);
//保存Xml文件
xmlDoc.Save(path); //path为:@"d:\anxiuyun.xml"
}