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C#(2):Xpath导航器XpathNavigator 、System.Xml.XPath

作者:互联网

XPathNavigator类包含移动和选择XML所需元素的所有方法。

一、创建:

二、读取

  1. 使用Select()方法通过XPath语句查询,得到XPathNodeIterator对象;
  2. 遍历XPathNodeIterator迭代器,MoveNext()方法移动下一个节点;Current属性表示当前节点;
//查询bookstore的子元素book中genre属性值为novel的所有节点
XPathNodeIterator iter = nav.Select("/bookstore/book[@genre='novel']");
while (iter.MoveNext())
{
    //迭代所有子代节点
    XPathNodeIterator newIter = iter.Current.SelectDescendants(XPathNodeType.Element, false);
    while (newIter.MoveNext())
    {
        Console.WriteLine(newIter.Current.Name + " : " + newIter.Current.Value);
    }
}

三、计算

使用Evaluate()方法计算表达式的值;

//统计图书总价   
Console.WriteLine("Total price = {0}", nav.Evaluate("sum(bookstore/book/price)"));

四、编辑

插入节点:先检查CanEdit属性是否为true,再使用InsertAfter()方法插入新节点。

XmlDocument doc = new XmlDocument();
doc.Load("./books.xml");
XPathNavigator nav2 = doc.CreateNavigator();
//判断是否可编辑
if (nav2.CanEdit)
{
    XPathNodeIterator iter = nav2.Select("bookstore/book/price");
    while (iter.MoveNext())
    {
        //在当前节点之后插入新节点
        iter.Current.InsertAfter("<disc>5</disc>");
    }
}
doc.Save("./newBooks.xml");

五、通过XPathNavigator转换为XMLReader,XMLWriter读写数据

//读:
XmlReader reader=nav.ReadSubtree();
while(reader.Read())
{
   Console.Write(reader.ReadOuterXml());
}

//写:
XmlWriter writer=XmlWriter.Create("./1.xml");
nav.WriteSubtree(writer);
writer.Close();

标签:Xpath,Xml,XpathNavigator,XPathNavigator,xml,doc,XmlDocument,iter,节点
来源: https://www.cnblogs.com/springsnow/p/12883391.html