1. book.xml
book.xml
<?xml version="1.0"?>
<catalog>
<book id="bk101">
<author>Gambardella, Matthew</author>
<title>XML Developer's Guide</title>
<genre>Computer</genre>
<price>44.95</price>
<publish_date>2000-10-01</publish_date>
<description>
An in-depth look at creating applications
with XML.
</description>
</book>
<book id="bk102">
<author>Ralls, Kim</author>
<title>Midnight Rain</title>
<genre>Fantasy</genre>
<price>5.95</price>
<publish_date>2000-12-16</publish_date>
<description>
A former architect battles corporate zombies,
an evil sorceress, and her own childhood to become queen
of the world.
</description>
</book>
<book id="bk103">
<author>Corets, Eva</author>
<title>Maeve Ascendant</title>
<genre>Fantasy</genre>
<price>5.95</price>
<publish_date>2000-11-17</publish_date>
<description>
After the collapse of a nanotechnology
society in England, the young survivors lay the
foundation for a new society.
</description>
</book>
<book id="bk104">
<author>Corets, Eva</author>
<title>Oberon's Legacy</title>
<genre>Fantasy</genre>
<price>5.95</price>
<publish_date>2001-03-10</publish_date>
<description>
In post-apocalypse England, the mysterious
agent known only as Oberon helps to create a new life
for the inhabitants of London. Sequel to Maeve
Ascendant.
</description>
</book>
<book id="bk105">
<author>Corets, Eva</author>
<title>The Sundered Grail</title>
<genre>Fantasy</genre>
<price>5.95</price>
<publish_date>2001-09-10</publish_date>
<description>
The two daughters of Maeve, half-sisters,
battle one another for control of England. Sequel to
Oberon's Legacy.
</description>
</book>
<book id="bk106">
<author>Randall, Cynthia</author>
<title>Lover Birds</title>
<genre>Romance</genre>
<price>4.95</price>
<publish_date>2000-09-02</publish_date>
<description>
When Carla meets Paul at an ornithology
conference, tempers fly as feathers get ruffled.
</description>
</book>
<book id="bk107">
<author>Thurman, Paula</author>
<title>Splish Splash</title>
<genre>Romance</genre>
<price>4.95</price>
<publish_date>2000-11-02</publish_date>
<description>
A deep sea diver finds true love twenty
thousand leagues beneath the sea.
</description>
</book>
<book id="bk108">
<author>Knorr, Stefan</author>
<title>Creepy Crawlies</title>
<genre>Horror</genre>
<price>4.95</price>
<publish_date>2000-12-06</publish_date>
<description>
An anthology of horror stories about roaches,
centipedes, scorpions and other insects.
</description>
</book>
<book id="bk109">
<author>Kress, Peter</author>
<title>Paradox Lost</title>
<genre>Science Fiction</genre>
<price>6.95</price>
<publish_date>2000-11-02</publish_date>
<description>
After an inadvertant trip through a Heisenberg
Uncertainty Device, James Salway discovers the problems
of being quantum.
</description>
</book>
<book id="bk110">
<author>O'Brien, Tim</author>
<title>Microsoft .NET: The Programming Bible</title>
<genre>Computer</genre>
<price>36.95</price>
<publish_date>2000-12-09</publish_date>
<description>
Microsoft's .NET initiative is explored in
detail in this deep programmer's reference.
</description>
</book>
<book id="bk111">
<author>O'Brien, Tim</author>
<title>MSXML3: A Comprehensive Guide</title>
<genre>Computer</genre>
<price>36.95</price>
<publish_date>2000-12-01</publish_date>
<description>
The Microsoft MSXML3 parser is covered in
detail, with attention to XML DOM interfaces, XSLT processing,
SAX and more.
</description>
</book>
<book id="bk112">
<author>Galos, Mike</author>
<title>Visual Studio 7: A Comprehensive Guide</title>
<genre>Computer</genre>
<price>49.95</price>
<publish_date>2001-04-16</publish_date>
<description>
Microsoft Visual Studio 7 is explored in depth,
looking at how Visual Basic, Visual C++, C#, and ASP+ are
integrated into a comprehensive development
environment.
</description>
</book>
</catalog>
2. 新建一个类,包括两个主要的成员：Document
class XPathSample
{
XPathDocument Document;
XPathNavigator Navigator;
};
3.使用构造函数进行初始化
public XPathSample()
{
Document = new XPathDocument("books.xml");
Navigator = Document.CreateNavigator();
}
4. 遍历所有的节点，输出xml中所有的数据
void NavigateDocument()
{
Navigator.MoveToRoot();
Navigator.MoveToFirstChild();
if(Navigator.NodeType == XPathNodeType.Element)
{
if(Navigator.HasChildren == true)
{
Navigator.MoveToFirstChild();
do
{
if(Navigator.HasAttributes == true)
{
Console.WriteLine("Book ID: " + Navigator.GetAttribute("id", ""));
}
if(Navigator.HasChildren)
{
Navigator.MoveToFirstChild();
do
{
Console.Write("\t{0}:\t{1}\r\n", Navigator.Name, Navigator.Value);
} while(Navigator.MoveToNext());
Navigator.MoveToParent();
}
} while(Navigator.MoveToNext());
}
}
}
5. 用表达式检索出满足特定条件的节点信息
void XPathExpression1()
{
Console.WriteLine("select out the book with ID bk103:");
var expr = Navigator.Compile("/catalog/book[@id='bk103']");
var iterator = Navigator.Select(expr);
while(iterator.MoveNext())
{
var nav = iterator.Current.Clone();
Console.WriteLine("Book ID: " + nav.GetAttribute("id", ""));
if(nav.HasChildren)
{
nav.MoveToFirstChild();
do
{
Console.Write("\t{0}:\t{1}\r\n", nav.Name, nav.Value);
} while(nav.MoveToNext());
}
}
}
6. 检索价格大于10的所有图书
void XPathExpression2()
{
Console.WriteLine("select out all books whose price are more than 10:");
var expr = Navigator.Compile("/catalog/book[price>10]");
var iterator = Navigator.Select(expr);
while(iterator.MoveNext())
{
var nav = iterator.Current.Clone();
Console.WriteLine("Book ID: " + nav.GetAttribute("id", ""));
if(nav.HasChildren)
{
nav.MoveToFirstChild();
do
{
if(nav.Name == "title")
{
Console.Write("\t{0}:\t{1}\r\n", nav.Name, nav.Value);
}
if(nav.Name == "price")
{
Console.Write("\t{0}:\t{1}\r\n", nav.Name, nav.Value);
}
} while(nav.MoveToNext());
}
}
}
7. 统计图书的平均价格
void XPathExpression3()
{
Console.WriteLine("calculate the average price of all books:");
var expr = Navigator.Compile("sum(/catalog/book/price) div count(/catalog/book/price)");
var averagePrice = Navigator.Evaluate(expr).ToString();
Console.WriteLine("The average price of the books are {0}", averagePrice);
}
这是xpath的基本使用方法，关键是要灵活使用表达式进行查询。
