1. XML DOM Overview
XML documents are case sensitive, attributes are enclosed in quotes, and each tag must be closed.
DOM is a tree-like representation of an XML document in memory.
Inheritance relationship diagram:
XmlNode;//XML node......XmlDocument;//XML Documentation............XmlDataDocument;//Document related to Dataset......XmlDocumentFragment;// Document snippet......XmlLinkedNode;//Connect nodes (abstract class)............XmlDeclaration;//XML statement:............XmlDocumentType;//Document Type............XmlElement;//element............XmlEntityReference;//Entity reference node............XmlProcessingInstruction;//Processing instructions............XmlCharacterData;//Character data (abstract class)..................XmlCDataSection;//CDATA Festival..................XmlComment;//Note..................XmlSignificantWhitespace;//Effective blank..................XmlWhitespace;//blank..................XmlText;//Text content of element or attribute......XmlAttribute;//property......XmlEntity;//Entity Statement......XmlNotation;//Notation Statement
2. XML members
1. XMl node: XmlNode
1. Attributes:
- ChildNodes: All child nodes.
- FirstChild: The first child.
- HasChildNodes: Get whether there are any child nodes.
- LastChild: The last child node.
- ParentNode: Parent node (for nodes that can have parent).
- NextSibling: A sibling node immediately after this node.
- PreviousSibling: A sibling node immediately before this node.
- InnerText: Text values of a node and all its child nodes.
- InnerXml: XML tags for child nodes.
-
OuterXml: This node and all its child nodes XML tags.
- NodeType: Get the type of the current node.
- Value: The value of the node.
- Attributes: The node's properties XmlAttributeCollection.
- OwnerDocument: The XmlDocument to which the node belongs.
2. Method:
- AppendChild(XmlNode): Added to the end of the child node list of this node.
- PrependChild(XmlNode): Append to the beginning of the child node list of this node.
- InsertAfter(XmlNode, XmlNode): Insert the specified node immediately after the specified node.
-
InsertBefore(XmlNode, XmlNode): Insert the specified node immediately before inserting the specified node.
- RemoveAll() : Removes all child nodes and/or properties of the current node.
- RemoveChild(XmlNode): Removes the specified child node.
- ReplaceChild(XmlNode, XmlNode): Replace child node newChild with the oldChild node.
- SelectNodes(String): Select a list of nodes matching the XPath expression.
- SelectSingleNode(String): Select the first XmlNode that matches the XPath expression.
- WriteContentTo(XmlWriter): When rewritten in a derived class, all children of the node are saved to the specified XmlWriter.
- WriteTo(XmlWriter): When rewritten in the derived class, save the current node to the specified XmlWriter.
- Clone() : Create a copy of this node.
- CloneNode(Boolean): Creates a copy of the node when rewritten in the derived class
- CreateNavigator() : Create XPathNavigator to browse this object.
2. XML document: XMLDocument
1. Attributes:
- DocumentElement: Get the root of the document XmlElement.
- DocumentType: Get the node containing the DOCTYPE declaration.
- PreserveWhitespace : Gets or sets a value indicating whether to keep a blank area in the element content.
- Schemas : Gets or sets the XmlSchemaSet object associated with this XmlDocument.
- XmlResolver: Set up XmlResolver for parsing external resources.
2. Method:
- GetElementById(String): Gets the XmlElement with the specified ID.
- GetElementsByTagName(String): Returns an XmlNodeList that contains a list of all child elements that match the specified Name.
- ImportNode(XmlNode, Boolean): Imports a node from another document to the current document. Load(Stream) Loads the XML document from the specified stream.
- Load(String): Load the XML document from the specified URL. .
- LoadXml(String): Load the XML document from the specified string.
- Save(String): Save the XML document to the specified file. If the specified file exists, this method overwrites it.
- Validate(ValidationEventHandler): Verify that XmlDocument is the XML Schema Definition Language (XSD) schema contained in the Schemas property.
- ReadNode(XmlReader): Create an XmlNode object based on the information in XmlReader. The reader must be positioned on a node or property.
-
Create****(String): Creates Xml*** with the specified Name.
- CreateNavigator() : Creates a new XPathNavigator object to navigate this document.
3. Events:
- NodeChanging、NodeChanged：Occurs when the value of the node belonging to the document will be changed.
- NodeInserting、NodeInserted：Occurs when a node belonging to the document is inserted into another node.
- NodeRemoving、NodeRemoved：Occurs when a node belonging to the document has been removed from its parent.
3. XML element: XmlElement
1. Attributes:
- HasAttributes: Gets a boolean value indicating whether the current node has any attributes.
- IsEmpty: Get or set the marking format of the element.
- SchemaInfo: Get the post-schema verification information set assigned to this node as the result of schema verification.
2. Method:
- GetAttribute(String): Returns the value of the attribute with the specified name.
- GetAttributeNode(String): Returns XmlAttribute with the specified name.
- HasAttribute(String): Determines whether the current node has a characteristic with the specified name.
- GetElementsByTagName(String): Returns an XmlNodeList that contains a list of all child elements that match the specified Name.
- RemoveAllAttributes() : Removes all specified properties from the element. The default feature is not removed.
- RemoveAttribute(String): Removes attributes by name.
- RemoveAttributeAt(Int32): Removes the attribute node with the specified index from the element. (If the removed feature has a default value, it will be replaced immediately).
- RemoveAttributeNode(String, String): Removes the XmlAttribute specified by the local name and namespace URI. (If the removed feature has a default value, it will be replaced immediately)
3. Create and query XML
Namespaces to be added:
using ;
1. Create XmlDocument
XmlDocument xmldoc = new XmlDocument();
//Add to XML declaration paragraph,XmlDeclaration xmldecl;
xmldecl =
("1.0", "gb2312", null);
(xmldecl);
//Add a root elementXmlElement xmlelem =
("", "Employees", "");
(xmlelem);
//Add another elementfor (int i = 1; i < 3; i++)
{
XmlNode root = ("Employees");//Find XmlElement xe1 = ("Node");//Create a node ("genre", "Li Zanhong");//Set the genre attribute of this node ("ISBN", "2-3631-4");//Set the ISBN attribute of this node
XmlElement xesub1 = ("title");
= "CS from Beginner to Mastery";//Set text node
(xesub1);//Add to node
XmlElement xesub2 = ("author");
= "Hou Jie";
(xesub2);
XmlElement xesub3 = ("price");
= "58.3";
(xesub3);
(xe1);//Add to node
}
//Save the created XML document("../../");Result: A file named is generated, with the following contents,
<xml version="1.0" encoding="gb2312"?>
<Employees>
<Node genre="Li Zanhong" ISBN="2-3631-4">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
<Node genre="Li Zanhong" ISBN="2-3631-4">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
</Employees>2. Create XmlTextWriter
See:XmlReader and XMLWriter (abstract class)
string strFilename = "../../";
XmlTextWriter xmlWriter = new XmlTextWriter(strFilename, );//
Create axmldocument
= ;
();
("Employees");
("Node");
("genre", "Li Zanhong");
("ISBN", "2-3631-4");
("title");
("CS from Beginner to Mastery");
();
("author");
("Hou Jie");
();
("price");
("58.3");
();
();
();
();result:
<xml version="1.0" encoding="gb2312"?>
<Employees>
<Node genre="Li Zanhong" ISBN="2-3631-4">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
</Employees>3. Create XML fragments: ()
XmlDocument xmldoc = new XmlDocument(); XmlDocumentFragment docFrag = (); = "aa"; (); XmlElement root = ; (docFrag);
4. Load the existing XML file: ()
XmlDocument xmldoc = new XmlDocument();
((""));
XmlElement root = ;//Get the root elementforeach (XmlNode node in )
{
if (["gere"].Value == "a")
{
foreach (XmlNode node1 in )
{
if ( == "author")
{
= "aa";//Modify the text }
}
}
}5. Query node: SelectNodes
string str = @"
200
Authentication information matching
";
var xd = new ();
(str);//xml loads xml string
XmlNamespaceManager nsManager = new XmlNamespaceManager();//Create a namespace manager
("xsd", "http:///2001/XMLSchema");// When adding strings, the namespace manager will atomize these strings.("xsi", "http:///2001/XMLSchema-instance");
("amon", "/");
var rowNoteList = ("//amon:ErrorRes", nsManager);//Find nodes(rowNoteList[0]);return:
<ErrorRes xmlns="/">
<Err_code>200</Err_code>
<Err_content>Authentication information matching</Err_content>
</ErrorRes>6. Read xml:StreamReader according to text file
StreamReader myFile = new StreamReader("../../", );//Notice
string myString = ();//myString is a read string();
(myString);4. Add a node: AppendChild
XmlDocument xmlDoc = new XmlDocument();
("../../");
XmlNode root = ("Employees");//Find
XmlElement xe1 = ("Node");//Create a node
("genre", "Zhang San");//Set the genre attribute of this node("ISBN", "1-1111-1");//Set the ISBN attribute of this node
XmlElement xesub1 = ("title");
= "C#Beginner Help";//Set Text Node
(xesub1);//Add to node
XmlElement xesub2 = ("author");
= "Master";
(xesub2);
XmlElement xesub3 = ("price");
= "158.3";
(xesub3);
(xe1);//Add to node
("../../");Result: A node was added to the original content of the xml, with the following content,
<xml version="1.0" encoding="gb2312"?>
<Employees>
<Node genre="Li Zanhong" ISBN="2-3631-4">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
<Node genre="Li Zanhong" ISBN="2-3631-4">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
<Node genre="Zhang San" ISBN="1-1111-1">
<title>C#Beginner Help</title> <author>Expert</author>
<price>158.3</price>
</Node>
</Employees>5. Modify nodes
1. Modify the value of the node (properties and subnodes):
XmlDocument xmlDoc = new XmlDocument();
("../../");
XmlNodeList nodeList = ("Employees").ChildNodes;//Get all child nodes of Employees node
foreach (XmlNode xn in nodeList)//Transfer all child nodes{
XmlElement xe = (XmlElement)xn;//Convert child node type to XmlElement type if (("genre") == "Zhang San")//If the genre attribute value is "Zhang San" {
("genre", "update Zhang San");//Then modify this property to "update Zhang San" XmlNodeList nls = ;//Continue to get all children of xe child nodes foreach (XmlNode xn1 in nls)//Travel {
XmlElement xe2 = (XmlElement)xn1;//Convert type if ( == "author")//If found {
= "Asia Victory";//Modify }
}
}
}
("../../");//save。Result: All the original node information has been modified, the content of the xml is as follows.
<xml version="1.0" encoding="gb2312"?>
<Employees>
<Node genre="Li Zanhong" ISBN="2-3631-4">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
<Node genre="Li Zanhong" ISBN="2-3631-4">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
<Node genre="update Zhang San" ISBN="1-1111-1">
<title>C#Beginner Help</title> <author>Asia Win</author>
<price>158.3</price>
</Node>
</Employees>2. Modify nodes (add node properties and add node sub-nodes)
XmlDocument xmlDoc = new XmlDocument();
("../../");
XmlNodeList nodeList = ("Employees").ChildNodes;//Get all child nodes of Employees node
foreach (XmlNode xn in nodeList)
{
XmlElement xe = (XmlElement)xn;
("test", "111111");//Add attributes
XmlElement xesub = ("flag");
= "1";
(xesub);//Add child nodes}
("../../");Result: One property of each node is added, and one child node is also added, the content is as follows.
<xml version="1.0" encoding="gb2312"?>
<Employees>
<Node genre="Li Zanhong" ISBN="2-3631-4" test="111111">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
<flag>1</flag>
</Node>
<Node genre="Li Zanhong" ISBN="2-3631-4" test="111111">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
<flag>1</flag>
</Node>
<Node genre="update Zhang San" ISBN="1-1111-1" test="111111">
<title>C#Beginner Help</title> <author>Asia Win</author>
<price>158.3</price>
<flag>1</flag>
</Node>
</Employees>6. Delete nodes
1. Delete a certain attribute in the node:
XmlDocument xmlDoc = new XmlDocument();
("../../");
XmlNodeList xnl = ("Employees").ChildNodes;
foreach (XmlNode xn in xnl)
{
XmlElement xe = (XmlElement)xn;
("genre");//Delete the genre attribute
XmlNodeList nls = ;//Continue to get all children of xe child nodes
foreach (XmlNode xn1 in nls)//Travel {
XmlElement xe2 = (XmlElement)xn1;//Convert type
if ( == "flag")//If found {
(xe2);//Delete }
}
}
("../../");Result: A property of a node and a child node of a node are deleted. The content is as follows.
<xml version="1.0" encoding="gb2312"?>
<Employees>
<Node ISBN="2-3631-4" test="111111">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
<Node ISBN="2-3631-4" test="111111">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
<Node ISBN="1-1111-1" test="111111">
<title>C#Beginner Help</title> <author>Asia Win</author>
<price>158.3</price>
</Node>
</Employees>2. Delete nodes:
XmlDocument xmlDoc = new XmlDocument();
("../../");
XmlNode root = ("Employees");
XmlNodeList xnl = ("Employees").ChildNodes;
for (int i = 0; i < ; i++)
{
XmlElement xe = (XmlElement)(i);
if (("genre") == "Zhang San")
{
(xe);
if (i < ) i = i - 1;
}
}
("../../");Result: All nodes that meet the conditions were deleted, the original content:
<xml version="1.0" encoding="gb2312"?>
<Employees>
<Node genre="Li Zanhong" ISBN="2-3631-4">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
<Node genre="Li Zanhong" ISBN="2-3631-4">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
<Node genre="Zhang San" ISBN="1-1111-1">
<title>C#Beginner Help</title> <author>Expert</author>
<price>158.3</price>
</Node>
<Node genre="Zhang San" ISBN="1-1111-1">
<title>C#Beginner Help</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>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
<Node genre="Li Zanhong" ISBN="2-3631-4">
<title>CSFrom Beginner to Mastery</title>
<author>Hou Jie</author>
<price>58.3</price>
</Node>
</Employees>3. Replace child elements
XmlElement elem=("title");
="XX";
(elem,);This is all about this article about C# using XmlDocument to operate XML. I hope it will be helpful to everyone's learning and I hope everyone will support me more.