C#中读取xml文件指定节点

参考：Select XML Nodes by Name

假设xml文件内容是

<?xml version="1.0" encoding="utf-8"?>
<Workflow>
<Activity>
<ActivityId>1</ActivityId>
<ActivityName>start</ActivityName>
<BindingPageId>1</BindingPageId>
<BindingRoleId>1</BindingRoleId>
<ActivityLevel>1</ActivityLevel>
</Activity>
<Activity>
<ActivityId>2</ActivityId>
<ActivityName>pass</ActivityName>
<BindingPageId>2</BindingPageId>
<BindingRoleId>2</BindingRoleId>
<ActivityLevel>2</ActivityLevel>
</Activity>
</Workflow>

我们需要读取Activity节点下的内容，因为存在多个Activity，所以需要读取多个节点。可以使用 XmlDocument.SelectSingleNode和XmlDocument.SelectNodes方法查找节点。前一个是查找匹配的第一个节点，而后一个则会返回一个节点列表。

1.XmlDocument.SelectSingleNode方法的使用

首先创建一个读取xml文件的方法ReadXmlNode

/// <summary>
/// 读取xml中的指定节点的值
/// </summary>
public void ReadXmlNode(string filename)
{
XmlDocument xmlDoc = new XmlDocument();
try
{
xmlDoc.Load(filename);
//读取Activity节点下的数据。SelectSingleNode匹配第一个Activity节点
XmlNode root = xmlDoc.SelectSingleNode("//Activity");//当节点Workflow带有属性是，使用SelectSingleNode无法读取
if (root != null)
{
string ActivityId = (root.SelectSingleNode("ActivityId")).InnerText;
string ActivityName = (root.SelectSingleNode("ActivityName ")).InnerText;
string ActivityLevel = root.SelectSingleNode("ActivityLevel").InnerText;
Console.WriteLine("ActivityId:" + ActivityId + "/nActivityName:" + ActivityName + "/nActivityLevel:" + ActivityLevel);
}
else
{
Console.WriteLine("the node  is not existed");
//Console.Read();
}
}
catch (Exception e)
{
//显示错误信息
Console.WriteLine(e.Message);
}
}

然后在主函数中调用该方法

class Program
{
static void Main(string[] args)
{
XMLOperation xmlOpr = new XMLOperation();
xmlOpr.ReadXmlNode("activity.xml");
Console.Read();
}
}

输出结果为：

ActivityId:1
ActivityName:start
ActivityLevel:1

2.XmlDocument.SelectNodes方法的使用

/// <summary>
/// 读取xml中的指定节点的值，如果有多个同名节点，则全部读取
/// </summary>
public void ReadXmlNodes(string filename)
{
XmlDocument xmlDoc = new XmlDocument();
try
{
xmlDoc.Load(filename);
XmlNodeList xnList = xmlDoc.SelectNodes("//Activity");
Console.WriteLine("共有{0}个节点", xnList.Count);//输出xnList中节点个数。
foreach (XmlNode xn in xnList)
{
//无法使用xn["ActivityId"].InnerText
string ActivityId = (xn.SelectSingleNode("ActivityId")).InnerText;
string ActivityName = xn.SelectSingleNode("ActivityName").InnerText;
string ActivityLevel = xn.SelectSingleNode("ActivityLevel").InnerText;
//  Console.WriteLine("ActivityId:" + ActivityId + "/nActivityName:" + ActivityName + "/nActivityLevel:" + ActivityLevel);
Console.WriteLine("ActivityId:  {0}/nActivityName:  {1}/nActivityLevel:  {2}", ActivityId, ActivityName, ActivityLevel);
}
}
catch (Exception e)
{
//显示错误信息
Console.WriteLine(e.Message);
}
}

然后在主函数中调用该方法

class Program
{
static void Main(string[] args)
{
XMLOperation xmlOpr = new XMLOperation();
xmlOpr.ReadXmlNodes("activity.xml");
Console.Read();
}
}

输出结果为：

共有2个节点
ActivityId: 1
ActivityName: start
ActivityLevel: 1
ActivityId: 2
ActivityName: pass
ActivityLevel: 2

3.通过节点属性查找指定节点

参考http://www.csharp-examples.net/xml-nodes-by-attribute-value/，虽然没有用到参考文章中的方法，不过总觉得以后会用到的。

/// <summary>
///通过ActivityLevel获取xmlnode，需要保证ActivityLevel在一个xml文档中是唯一的。
/// </summary>
public XmlNode getXmlNode(string filename, string activitylevel)
{
XmlDocument xmlDoc = new XmlDocument();
try
{
xmlDoc.Load(filename);
XmlNodeList xnList = xmlDoc.SelectNodes("//Activity");//当节点Workflow带有属性是，使用SelectSingleNode无法读取
foreach (XmlNode xn in xnList)
{
string ActivityLevel = xn.SelectSingleNode("ActivityLevel").InnerText;
if(activitylevel==ActivityLevel)
{
return xn;
}
}
}
catch (Exception e)
{
//显示错误信息
Console.WriteLine(e.Message);
}
return null;
}

然后在主函数中调用该方法

class Program
{
static void Main(string[] args)
{
XMLOperation xmlOpr = new XMLOperation();
XmlNode xn=xmlOpr.getXmlNode("activity.xml", "2");
string ActivityId = (xn.SelectSingleNode("ActivityId")).InnerText;
string ActivityName = (xn.SelectSingleNode("ActivityName ")).InnerText;
string ActivityLevel = xn.SelectSingleNode("ActivityLevel").InnerText;
Console.WriteLine("ActivityId:" + ActivityId + "/nActivityName:" + ActivityName + "/nActivityLevel:" + ActivityLevel);
Console.Read();
}
}

输出结果为：

ActivityId:2
ActivityName:pass
ActivityLevel:2