How to operate XML (zt) in C #. net)

Http://weekzero.cnblogs.com/articles/178140.html
How to operate XML in C #. net
Namespace to be added:
Using system. xml;

Define several public objects:
Xmldocument xmldoc;
Xmlnode;
Xmlelement xmlelem;

1. Create an XML file in the directory with the same name as the server:

Method 1:
Xmldoc = new xmldocument ();
// Add the Declaration section 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 another 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", "lizan red"); // you can specify the genre attribute of the node.
Xe1.setattribute ("ISBN", "2-3631-4"); // you can specify the ISBN attribute of the node.

Xmlelement xesub1 = xmldoc. createelement ("title ");
Xesub1.innertext = "Cs from entry to entry"; // set a text node
Xe1.appendchild (xesub1); // Add it to the <node> node
Xmlelement xesub2 = xmldoc. createelement ("author ");
Xesub2.innertext = "Hou Jie ";
Xe1.appendchild (xesub2 );
Xmlelement xesub3 = xmldoc. createelement ("price ");
Xesub3.innertext = "58.3 ";
Xe1.appendchild (xesub3 );

Root. appendchild (xe1); // Add it to the <employees> node.
}
// Save the created XML document
Xmldoc. Save (server. mappath ("data. xml "));

//////////////////////////////////////// //////////////////////////////////////// //////
Result: A file named data. XML is generated in the directory with the same name. The content is as follows,
<? XML version = "1.0" encoding = "gb2312"?>
<Employees>
<Node genre = "Li zanhong" ISBN = "2-3631-4">
<Title> Cs from entry to entry </title>
<Author> Hou Jie </author>
<Price> 58.3 </price>
</Node>
<Node genre = "Li zanhong" ISBN = "2-3631-4">
<Title> Cs from entry to entry </title>
<Author> Hou Jie </author>
<Price> 58.3 </price>
</Node>
</Employees>

Method 2:
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", "lizanhong ");
Xmlwriter. writeattributestring ("ISBN", "2-3631-4 ");

Xmlwriter. writestartelement ("title ");
Xmlwriter. writestring ("Cs from entry to entry ");
Xmlwriter. writeendelement ();

Xmlwriter. writestartelement ("author ");
Xmlwriter. writestring (" ");
Xmlwriter. writeendelement ();

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

Xmlwriter. writeendelement ();

Xmlwriter. Close ();
//////////////////////////////////////// //////////////////////////////////////// //////
Result:
<? XML version = "1.0" encoding = "gb2312"?>
<Employees>
<Node genre = "Li zanhong" ISBN = "2-3631-4">
<Title> Cs from entry to entry </title>
<Author> Hou Jie </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"); // you can specify the genre attribute of the node.
Xe1.setattribute ("ISBN", "1-1111-1"); // you can specify the ISBN attribute of the node.

Xmlelement xesub1 = xmldoc. createelement ("title ");
Xesub1.innertext = "C # Getting Started help"; // set a text node
Xe1.appendchild (xesub1); // Add it to the <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 it to the <employees> node.
Xmldoc. Save (server. mappath ("data. xml "));

//////////////////////////////////////// //////////////////////////////////////// //////
Result: A node is added to the original XML content. The content is as follows,
<? XML version = "1.0" encoding = "gb2312"?>
<Employees>
<Node genre = "Li zanhong" ISBN = "2-3631-4">
<Title> Cs from entry to entry </title>
<Author> Hou Jie </author>
<Price> 58.3 </price>
</Node>
<Node genre = "Li zanhong" ISBN = "2-3631-4">
<Title> Cs from entry to entry </title>
<Author> Hou Jie </author>
<Price> 58.3 </price>
</Node>
<Node genre = "zhangsan" ISBN = "1-1111-1">
<Title> C # Getting Started </title>
<Author> expert </author>
<Price> 158.3 </price>
</Node>
</Employees>

3. Modify the node value (attributes and subnodes ):

Xmldocument xmldoc = new xmldocument ();
Xmldoc. Load (server. mappath ("data. xml "));

Xmlnodelist nodelist = xmldoc. selectsinglenode ("employees"). childnodes; // obtain all child nodes of the employees Node

Foreach (xmlnode Xn in nodelist) // traverses all subnodes
{
Xmlelement Xe = (xmlelement) xn; // converts the subnode type to the xmlelement type
If (Xe. getattribute ("genre") = "Zhang San") // If the genre attribute value is "Zhang San"
{
Xe. setattribute ("genre", "Update Zhang San"); // modify the attribute to "Update Zhang San"

Xmlnodelist NLS = Xe. childnodes; // continue to obtain all the child nodes of the Xe subnode
Foreach (xmlnode xn1 in NLS) // traverse
{
Xmlelement xe2 = (xmlelement) xn1; // Conversion Type
If (xe2.name = "author") // If you find
{
Xe2.innertext = "Yasheng"; // modify
}
}
}
}
Xmldoc. Save (server. mappath ("data. xml"); // save.

///////////////////////////////////// //////////////////////////////////////// ////////
result: modify the information of all original nodes. The XML content is as follows:



CS entry-level knowledge </ title> <br> <author> Hou Jie </author> <br> <price> 58.3 </price> <br> </node> <br> <node genre =" li zanhong "ISBN =" 2-3631-4 "> <br> <title> CS entry to proficiency
Hou Jie
58.3


C # Getting Started
Yasheng
158.3

4. Modify the node (adding node attributes and adding the node's self-node ):
Xmldocument xmldoc = new xmldocument ();
Xmldoc. Load (server. mappath ("data. xml "));

Xmlnodelist nodelist = xmldoc. selectsinglenode ("employees"). childnodes; // obtain 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: an attribute is added for each node, and a subnode is added as follows,
<? XML version = "1.0" encoding = "gb2312"?>
<Employees>
<Node genre = "Li zanhong" ISBN = "2-3631-4" test = "111111">
<Title> Cs from entry to entry </title>
<Author> Hou Jie </author>
<Price> 58.3 </price>
<Flag> 1 </flag>
</Node>
<Node genre = "Li zanhong" ISBN = "2-3631-4" test = "111111">
<Title> Cs from entry to entry </title>
<Author> Hou Jie </author>
<Price> 58.3 </price>
<Flag> 1 </flag>
</Node>
<Node genre = "Update zhangsan" ISBN = "1-1111-1" test = "111111">
<Title> C # Getting Started </title>
<Author> Yasheng </author>
<Price> 158.3 </price>
<Flag> 1 </flag>
</Node>
</Employees>

5. delete an attribute in a 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 attributes

Xmlnodelist NLS = Xe. childnodes; // continue to obtain all the child nodes of the Xe subnode
Foreach (xmlnode xn1 in NLS) // traverse
{
Xmlelement xe2 = (xmlelement) xn1; // Conversion Type
If (xe2.name = "flag") // If
{
Xe. removechild (xe2); // Delete
}
}
}
Xmldoc. Save (server. mappath ("data. xml "));

///////////////////////////////////// //////////////////////////////////////// ////////]
result: A node attribute and a subnode of the node are deleted. The content is as follows:



CS entry-level knowledge
Hou Jie
58.3


CS entry to proficiency
Hou Jie
58.3


C # Getting Started
Yasheng
158.3

6. delete a 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: All nodes that meet the conditions are deleted. The original content is as follows:

<? XML version = "1.0" encoding = "gb2312"?>
<Employees>
<Node genre = "Li zanhong" ISBN = "2-3631-4">
<Title> Cs from entry to entry </title>
<Author> Hou Jie </author>
<Price> 58.3 </price>
</Node>
<Node genre = "Li zanhong" ISBN = "2-3631-4">
<Title> Cs from entry to entry </title>
<Author> Hou Jie </author>
<Price> 58.3 </price>
</Node>
<Node genre = "zhangsan" ISBN = "1-1111-1">
<Title> C # Getting Started </title>
<Author> expert </author>
<Price> 158.3 </price>
</Node>
<Node genre = "zhangsan" ISBN = "1-1111-1">
<Title> C # getting Getting Started </title>
<Author> expert </author>
<Price> 158.3 </price>
</Node>
</Employees>

Deleted content:
<? XML version = "1.0" encoding = "gb2312"?>
<Employees>
<Node genre = "Li zanhong" ISBN = "2-3631-4">
<Title> Cs from entry to entry </title>
<Author> Hou Jie </author>
<Price> 58.3 </price>
</Node>
<Node genre = "Li zanhong" ISBN = "2-3631-4">
<Title> Cs from entry to entry </title>
<Author> Hou Jie </author>
<Price> 58.3 </price>
</Node>
</Employees>

7. Read XML according to text files

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 the read string
Myfile. Close ();