C # Operations XML summary (beginner)

First, Brief introduction

Using System.Xml;
Initializing an XML instance
XmlDocument xml=new XmlDocument ();

Import the specified XML file
Xml. Load (path);
Xml. Load (HttpContext.Current.Server.MapPath ("~/file/bookstore.xml"));

Specify a node
XmlNode Root=xml. selectSingleNode ("/root");

Get all immediate child nodes under a node
XmlNodeList Childlist=root. ChildNodes;

Determine if there are child nodes under the node
Root. HasChildNodes;

Gets a collection of sibling nodes with the same name
XmlNodeList Nodelist=xml. SelectNodes ("/root/news");

Generate a new node
XmlElement Node=xml. CreateElement ("News");

Adds a node to the specified node as its child node
Root. AppendChild (node);

Before adding a node to a child node under a specified node
Root. InsertBefore (Node,root. Childenodes[i]);

Creates a new property for the specified node and assigns a value
Node. SetAttribute ("id", "11111");

To add a child node to a specified node
Root. AppendChild (node);

Gets the specified property value for the specified node
String Id=node. attributes["id"]. Value;

Gets the text in the specified node
String Content=node. InnerText;

Save the XML file
String Path=server.mappath ("~/file/bookstore.xml");
Xml. Save (path);
or Use:xml. Save (HttpContext.Current.Server.MapPath ("~/file/bookstore.xml"));

Second, specific examples

How XML is manipulated in C#.net
Namespaces that need to be added:
Using System.Xml;

Define several common objects:
XmlDocument xmldoc;
XmlNode XmlNode;
XmlElement Xmlelem;

1, create an XML file to the server directory with the same name:

Method One:
xmldoc = new XmlDocument ();
Join the declaration paragraph of XML, <?xml version= "1.0" encoding= "gb2312"?>
XmlDeclaration xmldecl;
Xmldecl = xmldoc. Createxmldeclaration ("1.0", "gb2312", null);
XmlDoc. AppendChild (XMLDECL);

Add a root element
Xmlelem = xmldoc. CreateElement ("", "Employees", "");
XmlDoc. AppendChild (Xmlelem);
Add a different element
for (int i=1;i<3;i++)
{

XmlNode Root=xmldoc. selectSingleNode ("Employees");//Find <Employees>
XmlElement Xe1=xmldoc. CreateElement ("node");//Create a <Node> node
Xe1. SetAttribute ("Genre", "Li Zhanhong");//Set the node genre property
Xe1. SetAttribute ("ISBN", "2-3631-4");//Set the node ISBN property

XmlElement Xesub1=xmldoc. CreateElement ("title");
Xesub1. Innertext= "CS from beginner to proficient";//Set Text node
Xe1. AppendChild (XESUB1);//Add to <Node> node
XmlElement Xesub2=xmldoc. CreateElement ("author");
Xesub2. Innertext= "Waiting for the Czech Republic";
Xe1. AppendChild (XESUB2);
XmlElement Xesub3=xmldoc. CreateElement ("Price");
Xesub3. innertext= "58.3";
Xe1. AppendChild (XESUB3);

Root. AppendChild (XE1);//Add to <Employees> node
}
Save the created XML document
XmlDoc. Save (Server.MapPath ("Data.xml"));

//////////////////////////////////////////////////////////////////////////////////////
Result: A file named Data.xml was generated under the same name, with the following
<?xml version= "1.0" encoding= "gb2312"?>
<Employees>
<node genre= "Li Zhanhong" isbn= "2-3631-4" >
<title>cs from getting started to mastering </title>
<author> </author>
<price>58.3</price>
</Node>
<node genre= "Li Zhanhong" isbn= "2-3631-4" >
<title>cs from getting started to mastering </title>
<author> </author>
<price>58.3</price>
</Node>
</Employees>

Method Two:
XmlTextWriter XmlWriter;
String strFileName = Server.MapPath ("Data1.xml");

XmlWriter = new XmlTextWriter (strfilename,encoding.default);//Create an XML document
xmlwriter.formatting = formatting.indented;
Xmlwriter.writestartdocument ();
Xmlwriter.writestartelement ("Employees");

Xmlwriter.writestartelement ("Node");
Xmlwriter.writeattributestring ("Genre", "Li Zhanhong");
Xmlwriter.writeattributestring ("ISBN", "2-3631-4");

Xmlwriter.writestartelement ("title");
Xmlwriter.writestring ("CS from beginner to proficient");
Xmlwriter.writeendelement ();

Xmlwriter.writestartelement ("author");
Xmlwriter.writestring ("Waiting for the Czech Republic");
Xmlwriter.writeendelement ();

Xmlwriter.writestartelement ("Price");
Xmlwriter.writestring ("58.3");
Xmlwriter.writeendelement ();

Xmlwriter.writeendelement ();

Xmlwriter.close ();
//////////////////////////////////////////////////////////////////////////////////////
Results:
<?xml version= "1.0" encoding= "gb2312"?>
<Employees>
<node genre= "Li Zhanhong" isbn= "2-3631-4" >
<title>cs from getting started to mastering </title>
<author> </author>
<price>58.3</price>
</Node>
</Employees>

2, add a node:

XmlDocument xmldoc=new XmlDocument ();
Xmldoc.load (Server.MapPath ("Data.xml"));
XmlNode Root=xmldoc.selectsinglenode ("Employees");//Find <Employees>
XmlElement xe1=xmldoc.createelement ("node");//Create a <Node> node
Xe1. SetAttribute ("Genre", "Zhang San");//Set the node genre property
Xe1. SetAttribute ("ISBN", "1-1111-1");//Set the node ISBN property

XmlElement xesub1=xmldoc.createelement ("title");
Xesub1. Innertext= "C # Getting Started help";//Setting Up a text node
Xe1. AppendChild (XESUB1);//Add to <Node> node
XmlElement xesub2=xmldoc.createelement ("author");
Xesub2. innertext= "Master";
Xe1. AppendChild (XESUB2);
XmlElement xesub3=xmldoc.createelement ("price");
Xesub3. innertext= "158.3";
Xe1. AppendChild (XESUB3);

Root. AppendChild (XE1);//Add to <Employees> node
Xmldoc.save (Server.MapPath ("Data.xml"));

//////////////////////////////////////////////////////////////////////////////////////
Result: A node is added to the original XML content as follows,
<?xml version= "1.0" encoding= "gb2312"?>
<Employees>
<node genre= "Li Zhanhong" isbn= "2-3631-4" >
<title>cs from getting started to mastering </title>
<author> </author>
<price>58.3</price>
</Node>
<node genre= "Li Zhanhong" isbn= "2-3631-4" >
<title>cs from getting started to mastering </title>
<author> </author>
<price>58.3</price>
</Node>
<node genre= "Zhang San" isbn= "1-1111-1" >
<title>c# Getting Started help </title>
<author> Master </author>
<price>158.3</price>
</Node>
</Employees>

3, modify the value of the node (attributes and sub-nodes):

XmlDocument xmldoc=new XmlDocument ();
Xmldoc.load (Server.MapPath ("Data.xml"));

XmlNodeList Nodelist=xmldoc.selectsinglenode ("Employees"). childnodes;//get all child nodes of the Employees node

foreach (XmlNode xn in nodeList)//traverse all child nodes
{
XmlElement xe= (XmlElement) xn;//to convert child node types to XmlElement types
if (XE. GetAttribute ("genre") = = "Zhang San")//if the genre attribute value is "Zhang San"
{
Xe. SetAttribute ("Genre", "Update Zhang San");//Modify this property to "Update Zhang San"

XmlNodeList Nls=xe. childnodes;//continue to acquire all child nodes of the XE child node
foreach (XmlNode xn1 in NLS)//traversal
{
XmlElement xe2= (XmlElement) xn1;//conversion type
if (Xe2. name== "Author")//If found
{
Xe2. innertext= "Ya sheng";//Modify
}
}
}
}
Xmldoc.save (Server.MapPath ("Data.xml"));//save.

//////////////////////////////////////////////////////////////////////////////////////
Result: The information for all the previous nodes has been modified , the contents of the XML are as follows,
<?xml version= "1.0" encoding= "gb2312"?
<employees>
  <node genre= "Li Zhanhong" Isbn= "2-3631-4";
    <title>cs from getting started to mastering </title>
    <author > </author>
    <price>58.3</price>
  </node>
  <node genre= "Li Zhanhong" isbn= "2-3631-4";
    <title>cs from getting started to mastering </title>
     <author> </author>
    <price>58.3</price>
  < /node>
  <node genre= "update Zhang San" isbn= "1-1111-1";
    <title>c# Getting Started help </ Title>,
    <author> </author>
    <price>158.3</ Price>
  </node>
</employees>

4, modify the node (add the node's attributes and add the node's self-node):
XmlDocument xmldoc=new XmlDocument ();
Xmldoc.load (Server.MapPath ("Data.xml"));

XmlNodeList Nodelist=xmldoc.selectsinglenode ("Employees"). childnodes;//get all child nodes of the Employees node

foreach (XmlNode xn in nodeList)
{
XmlElement xe= (XmlElement) xn;
Xe. SetAttribute ("Test", "111111");

XmlElement xesub=xmldoc.createelement ("flag");
Xesub. innertext= "1";
Xe. AppendChild (xesub);
}
Xmldoc.save (Server.MapPath ("Data.xml"));

//////////////////////////////////////////////////////////////////////////////////////
Result: The attributes of each node are added with one, and the sub-nodes are also added, the contents are as follows,
<?xml version= "1.0" encoding= "gb2312"?>
<Employees>
<node genre= "Li Zhanhong" isbn= "2-3631-4" test= "111111" >
<title>cs from getting started to mastering </title>
<author> </author>
<price>58.3</price>
<flag>1</flag>
</Node>
<node genre= "Li Zhanhong" isbn= "2-3631-4" test= "111111" >
<title>cs from getting started to mastering </title>
<author> </author>
<price>58.3</price>
<flag>1</flag>
</Node>
<node genre= "Update Zhang San" isbn= "1-1111-1" test= "111111" >
<title>c# Getting Started help </title>
<author> ya sheng </author>
<price>158.3</price>
<flag>1</flag>
</Node>
</Employees>

5, delete one of the properties in the node:
XmlDocument xmldoc=new XmlDocument ();
Xmldoc.load (Server.MapPath ("Data.xml"));
XmlNodeList Xnl=xmldoc.selectsinglenode ("Employees"). ChildNodes;
foreach (XmlNode xn in xnl)
{
XmlElement xe= (XmlElement) xn;
Xe. RemoveAttribute ("genre");//Delete genre property

XmlNodeList Nls=xe. CHILDNODES;//continues to acquire all child nodes of the XE child node  
foreach (XmlNode xn1 in NLS)//traverse  
{ 
XmlElement xe2= ( XmlElement) xn1;//conversion type  
if (Xe2. name== "flag")//if   is found;
{ 
Xe. RemoveChild (XE2);//delete
} 
} 
} 
Xmldoc.save (Server.MapPath ("Data.xml"));

//////////////////////////////////////////////////////////////////////////////////////]
Result: Delete A property of the endpoint and a sub-node of the node, as follows,
<?xml version= "1.0" encoding= "gb2312"?
<employees>
  <node isbn= "2-3631-4" test= "111111";
    <title>cs from getting started to mastering </title>
     <author> </author>
    <price>58.3</price>
  < /node>,
  <node isbn= "2-3631-4" test= "111111";
    <title>cs from getting started to mastering </ Title>,
    <author> </author>
    <price>58.3</ Price>
  </node>
  <node isbn= "1-1111-1" test= "111111";
    < title>c# starter Help </title>
    <author> </author>
    < Price>158.3</price>
  </node>
</employees>

6. Delete the node:
XmlDocument xmldoc=new XmlDocument ();
Xmldoc.load (Server.MapPath ("Data.xml"));
XmlNode Root=xmldoc.selectsinglenode ("Employees");
XmlNodeList Xnl=xmldoc.selectsinglenode ("Employees"). ChildNodes;
for (int i=0;i<xnl. count;i++)
{
XmlElement xe= (XmlElement) xnl. Item (i);
if (XE. GetAttribute ("genre") = = "Zhang San")
{
Root. RemoveChild (XE);
if (I<XNL. Count) i=i-1;
}
}
Xmldoc.save (Server.MapPath ("Data.xml"));

//////////////////////////////////////////////////////////////////////////////////////]
Result: Delete all the nodes that match the condition, the original content:

<?xml version= "1.0" encoding= "gb2312"?>
<Employees>
<node genre= "Li Zhanhong" isbn= "2-3631-4" >
<title>cs from getting started to mastering </title>
<author> </author>
<price>58.3</price>
</Node>
<node genre= "Li Zhanhong" isbn= "2-3631-4" >
<title>cs from getting started to mastering </title>
<author> </author>
<price>58.3</price>
</Node>
<node genre= "Zhang San" isbn= "1-1111-1" >
<title>c# Getting Started help </title>
<author> Master </author>
<price>158.3</price>
</Node>
<node genre= "Zhang San" isbn= "1-1111-1" >
<title>c# Getting Started help </title>
<author> Master </author>
<price>158.3</price>
</Node>
</Employees>

Content after deletion:
<?xml version= "1.0" encoding= "gb2312"?>
<Employees>
<node genre= "Li Zhanhong" isbn= "2-3631-4" >
<title>cs from getting started to mastering </title>
<author> </author>
<price>58.3</price>
</Node>
<node genre= "Li Zhanhong" isbn= "2-3631-4" >
<title>cs from getting started to mastering </title>
<author> </author>
<price>58.3</price>
</Node>
</Employees>

7, read the XML as a text file

System.IO.StreamReader MyFile =new
System.IO.StreamReader (Server.MapPath ("Data.xml"), System.Text.Encoding.Default);
Note System.Text.Encoding.Default

String myString = Myfile.readtoend ();//mystring is a read-out string
Myfile.close ();

third, advanced applications

/* Read XML data in two XML ways */
<aaa>
<bb>something</bb>
<cc>something</cc>
</aaa>

<aaa>
<add key= "123" value= "321"/>
</aaa>

/* First Method */
Ds. READXML ("Your xmlfile name");
Container.DataItem ("BB");
Container.DataItem ("CC");
Ds. ReadXmlSchema ("Your xmlfile name");

/* The second method */
<aaa>
<add key= "123" value= "321"/>
</aaa>
What should I do if I want to find 123 and then fetch 321?

Using System.Xml;
XmlDataDocument xmldoc = new System.Xml.XmlDataDocument ();
Xmldoc.load (@ "C:/config.xml");
XmlElement Elem = Xmldoc.getelementbyid ("add");
String str = Elem. attributes["Value"]. Value


/* Third method: selectSingleNode read XML in two formats *---/
--------------------------------------------------------------------
<?xml version= "1.0" encoding= "Utf-8"?>
<configuration>
<appSettings>
<connectionstring>data SOURCE=YF; User id=ctm_dbo;password=123</connectionstring>
</appSettings>
</configuration>
--------------------------------------------------------------------------
XmlDocument doc = new XmlDocument ();
Doc. Load (Strxmlname);

XmlNode Node=doc. selectSingleNode ("/configuration/appsettings/connectionstring");
if (node!=null)
{
String K1=node.    Value; Null
String K2=node. Innertext;//data SOURCE=YF; User id=ctm_dbo;password=123
String K3=node. Innerxml;//data SOURCE=YF; User id=ctm_dbo;password=123
Node=null;
}

********************************************************************
<?xml version= "1.0" encoding= "Utf-8"?>
<configuration>
<appSettings>
<add key= "ConnectionString" value= "Data source=yf; User id=ctm_dbo;password=123 "/>
</appSettings>
</configuration>
**--------------------------------------------------------------------**
XmlNode Node=doc. selectSingleNode ("/configuration/appsettings/add");
if (node!=null)
{
String K=node. attributes["Key"]. Value;
String V=node. attributes["Value"]. Value;
Node=null;
}
*--------------------------------------------------------------------*
XmlNode Node=doc. selectSingleNode ("/configuration/appsettings/add");
if (node!=null)
{
XmlNodeReader nr=new XmlNodeReader (node);
Nr. MoveToContent ();
Checks whether the current node is a content node. If this node is not a content node, the reader jumps forward to the next content node or end of the file.
Nr. MoveToAttribute ("value");
String S=nr. Value;
Node=null;
}

C # Operations XML summary (beginner)