Introduction to C # Two ways to read XML _c# tutorial

XML role

For XML, I guess you all know better, I do not have to use the ink to describe what it is, I think in the future of web development in the XML will certainly shine, XML is Extensible Markup Language, the enterprise can develop a set of its own data format. Data transfer for the Internet, I think, is the most tempting part of XML for US programmers!

Our topic today is not about the benefits of XML, but about how to use XML in C #. Let's take a look at some of the basics of using programs to access XML.

Two models for access:

Accessing and then manipulating XML files in programs there are generally two models, using the DOM (Document Object model) and the flow model, the advantage of using the DOM is that it allows editing and updating of XML documents, random access to the data in the document, and the use of XPath queries, but The disadvantage of DOM is that it requires a one-time load of the entire document into memory, which can cause resource problems for large documents. The flow model solves the problem very well, because its access to the XML file is based on the concept of a stream, that is, there is only the current node in memory at any time, but it also has its drawbacks, it is read-only, forward only, and cannot perform backward navigation in the document. Although there are advantages and disadvantages, but we can also in the process of the two and the implementation of complementary, hehe

DOM Document Object Model operations

Copy Code code as follows:

Using System.Xml;

XmlDocument xml=new XmlDocument ()//Initialize an XML instance
Xml. Load (path);//import the specified XML file
Xml. Load (HttpContext.Current.Server.MapPath ("~/file/bookstore.xml")); XmlNode Root=xml. selectSingleNode ("/root");//Specify a node
XmlNodeList Childlist=root. childnodes;//gets all the direct child nodes under the node
XmlNodeList Nodelist=xml. SelectNodes ("/root/news");//Gets the same sibling node collection string Id=node with the same name. attributes["id"]. value;//gets the specified attribute value for the specified node
String Content=node. innertext;//gets the text in the specified node
Root. haschildnodes;//determine if there are child nodes under this node

1. Properties of the XmlDocument class

The properties and descriptions of the XmlDocument class are shown in the following table.

Property	Description
Attributes	Collection of properties for the current node
BaseURI	Base URI of the current node
ChildNodes	All child nodes of a node
DocumentElement	The root of the document
DocumentType	Nodes declared by DOCTYPE
FirstChild	The first child node of a node
HasChildNodes	Whether there are any child nodes
Implementation	Gets the XmlImplementation object for the current document
InnerText	All text content that the node contains
InnerXml	All the XML content that the node contains
IsReadOnly	Whether the current node is read-only
Item	Gets the specified child element
LastChild	Last child node
LocalName	Gets the local name of the node
Name	Gets the qualified name of the node
NamespaceURI	Gets the namespace URI of the node
NameTable	Gets the xmlnametable associated with this implementation
NextSibling	Gets the node immediately after the node
NodeType	Gets the type of the current node
OuterXml	Gets a token representing this node and all its child nodes
Ownerdocument	Gets the XmlDocument that the current node belongs to
ParentNode	Gets the parent of this node (for nodes that can have a parent)
Prefix	Gets or sets the namespace prefix for this node
PreserveWhitespace	Gets or sets a value that indicates whether whitespace is preserved in element content
PreviousSibling	Gets the node immediately preceding the node
SchemaInfo	Returns the post-schema validation information set for a node (PSVI)
Schemas	Gets or sets the XmlSchemaSet object associated with this XmlDocument
Value	Gets or sets the value of a node
XmlResolver	Set up XmlResolver for resolving external resources

2. Methods of XmlDocument classes

The XmlDocument class method and description are shown in the following table.

Method	Description
AppendChild	Adds the specified node to the end of the list of child nodes of the node
CreateAttribute	Create a XmlAttribute with the specified name
Createcdatasection	Create a xmlcdatasection that contains the specified data
Createcomment	Create a xmlcomment that contains the specified data
Createdocumentfragment	Create XmlDocumentFragment
CreateDocumentType	Returns the new XmlDocumentType object
CreateElement	Create XmlElement
Createentityreference	Create a xmlentityreference with the specified name
CreateNavigator	Create a new XPathNavigator object for navigating this document
CreateNode	Create XmlNode
Createprocessinginstruction	Creates a xmlprocessinginstruction with the specified name and data
Createsignificantwhitespace	Create a XmlSignificantWhitespace node
createTextNode	Creates a XmlText with the specified text
Createwhitespace	Create a XmlWhitespace node
Createxmldeclaration	Creates a XmlDeclaration node with the specified value
getElementById	Gets the XmlElement with the specified ID
getElementsByTagName	Returns a XmlNodeList that contains a list of all elements that match the specified name
Getnamespaceofprefix	Finds the closest xmlns declaration for the given prefix within the current node range and returns the namespace URI in the declaration
Getprefixofnamespace	Finds the closest xmlns declaration for the given namespace URI within the current node range and returns the prefix defined in the Declaration
GetType	Gets the Type of the current instance
ImportNode	Import a node from another document into the current document
InsertAfter	Inserts the specified node immediately after the specified reference node
InsertBefore	Inserts the specified node immediately before the specified reference node
Load	Loading the specified XML data
Loadxml	Loads an XML document from a specified string
Normalize	Convert the XmlText node to the "normal" form
PrependChild	Adds the specified node to the beginning of the list of child nodes of the node
ReadNode	Creates a XmlNode object based on the information in the XmlReader. The reader must be positioned on a node or property
RemoveAll	Remove all child nodes and/or attributes of the current node
RemoveChild	Removes the specified child node
ReplaceChild	Replace old node with new node
Save	To save an XML document to a specified location
SelectNodes	Select a list of nodes that match an XPath expression
selectSingleNode	Select the first XmlNode to match an XPath expression
Supports	Testing whether the DOM implementation implements specific functionality
Validate	Verify that XmlDocument is not an XML schema definition language (XSD) schema that is contained in the Schemas property.
WriteContentTo	Saves all children of the XmlDocument node to the specified XmlWriter
WriteTo	Saves the XmlDocument node to the specified XmlWriter

The following is an introduction to common methods.

(1) Load method

This method can import XML data from an XML file specified by a string or from a stream object, a TextReader object, and a XmlReader object.

(2) Loadxml method

This method completes the ability to import XML data from a particular XML file. By default, the Loadxml method neither preserves whitespace nor preserves meaningful whitespace. This method does not perform DTD or schema validation.

(3) Save method

This method saves the XML data to an XML file or a Stream object, a TextReader object, and a XmlReader object to import the XML data.

3. Events for XmlDocument classes

XmlDocument class events and descriptions are shown in the following table.

Table XmlDocument event and description of class

Event	Description
NodeChanged	Occurs when the value of the node that belongs to the document has been changed
Nodechanging	Occurs when the Value of the node that belongs to the document is changed
NodeInserted	Occurs when a node belonging to this document has been inserted into another node
Nodeinserting	Occurs when the node that belongs to the document is inserted into another node
Noderemoved	Occurs when a node belonging to the document has been removed from its parent
Noderemoving	Occurs when the node that belongs to the document is removed from the document

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