JAXP's DOM summary

first, JAXP, Dom introduction

Jaxp:java API for XML programing

Dom:document Object method

DOM Features:

(1) All the XML documents are put into memory for parsing, so memory consumption is consumed;

(2) to be able to the XML to be added to the search;

<person>
	<name>xiazdong</name>
	<age>20</age>
</person>

To become a DOM tree:

Second, DOM API

Dom's commonly used classes are: Documentbuilderfactory, Documentbuilder, Document, Node, NodeList, Element, Attribute, Transformerfactory, Transformer, Domsource, Streamresult and other categories;

DOM Development steps:

(1) obtaining documentbuilder through documentbuilderfactory;

(2) parsing XML through Documentbuilder, and obtaining document (root node of documents);

(3) the operation through document;

(4) If you make changes to the XML, you need to transformerfactory create a transformer;

(5) preservation through transformer;

Common Operations
the Documentbuilderfactory classes are:

(1) Documentbuilderfactory factory = documentbuilderfactory. newinstance ();

(2) Documentbuilder builder = Factory.newdocumentbuilder ();
the Documentbuilder classes are:

(1) Document document = Builder.parse (new File (""))/parse XML and return to document node

(2) Document document = Builder.newdocument (); Create a document

The document classes are:

(1) NodeList list = getElementsByTagName ("name");//queue to get <name> label

(2) Element e = document.createelement ("name"); Create a <name> tag, and return

The NodeList classes are:

(1) Node node = Nodelist.item (i); To get the i+1 node of a node queue

(2) int length = Nodelist.getlength (); To get the length of a node queue

the node has:

(1) String text = Node.gettextcontent (); Get the value of a node

(2) Node.appendchild (node child); Add a child subnode to node tail

(3) Node.insertbefore (node Child,node beforenode);//Add a child subnode before the Beforenode child node of node

(4) NodeList list = Node.getchildnodes (); Get all child nodes of node

(5) Node parent = Node.getparentnode (); Get node's parent

(6) Node.removechild (node child); Remove child children nodes of node

(7) node.settextcontent (String text); Set node's value

(8) String name = Node.getnodename (); Get the name of the label
the element has:
In addition to the node class approach, there are

(1) Element.setattribute ("name", "value"); Set the properties of a label

(2) String value = Element.getattribute ("name"); Get the properties of a label

(3) Element.removeattribute ("name")//Remove Label properties

the tranformerfactory are:

(1) Transformerfactory tfactory = Transformerfactory.newinstance ();

(2) Transformer tf = Tfactory.newtransformer ();

the transformer are:

(1) tf.transform (Source source,result result); Output

the Domsource are:

(1) Domsource Source = new Domsource (document document);

the Streamresult are:

(1) Streamresult result = new Streamresult (New FileOutputStream ("1.xml"));

Iii. dom for crud
XML is:

<?xml version= "1.0" encoding= "UTF-8" standalone= "no"?>
<personlist>
	<person>
		< Name aaa= "xxxx" >xiazdong-1</name>
		<age>20</age>
		<salary>1000</salary>
	</person>
	<person>
		<name>xiazdong-2</name>
		<age>21</age>
		<salary>2000</salary>
	</person>
</personlist>

1.Create

private static void Create (Documentbuilder builder) throws Exception {
	Document document = Builder.newdocument (); 
  element root = document.createelement ("person");
	Element name = document.createelement ("name");
	Name.settextcontent ("Xiazdong");
	Element age = document.createelement (' age ');
	Age.settextcontent ("a");
	Root.appendchild (name);
	Root.appendchild (age);
	Document.appendchild (root);
	Transformerfactory tfactory = Transformerfactory.newinstance ();
	Transformer tf = Tfactory.newtransformer ();
	Tf.transform (new Domsource (document), New Streamresult (New FileOutputStream ("Output.xml"));
}

private static void Insert (document document) throws Exception {
	Node person = document.getelementsbytagname (' Person "). Item (0);
	Node name = document.getElementsByTagName ("name"). Item (0);
	Element tmp = document.createelement ("Tmpchild");
	Tmp.settextcontent ("xxx");
	Person.insertbefore (tmp, name);
	Transformerfactory tfactory = Transformerfactory.newinstance ();
	Transformer tf = Tfactory.newtransformer ();
	Tf.transform (new Domsource (document), New Streamresult (New FileOutputStream ("1.xml"));
}

2.Read

private static void Read (document document) {
		node node = document.getelementsbytagname (' name '). Item (0);
		String name = Node.getnodename ();
		String value = Node.gettextcontent ();
		String attr = ((Element) node). getattribute ("AAA");
		SYSTEM.OUT.PRINTLN (name);
		System.out.println (value);
		System.out.println (attr);
	}

Application: Traverse the entire XML document and output

private static void ReadAll (document document) {
	Node root = document.getElementsByTagName ("Personlist"). Item (0); C1/>read (root);
}

private static void Read (node node) {
	if (node instanceof Element)
		System.out.print ("<" +node.getnodename () + "></" +node.getnodename () + ">");
	NodeList list = Node.getchildnodes ();
	for (int i=0;i<list.getlength (); i++) {
		Node n = list.item (i);
		Read (n);
	}	
}

3.Update

private static void Update (document document) throws Exception {
	node node = document.getelementsbytagname (' name '). Item (0);
	Node.settextcontent ("Xiazdong");
	Element e = (element) node;
	E.setattribute ("AAA", "a");
	Transformerfactory tfactory = Transformerfactory.newinstance ();
	Transformer tf = Tfactory.newtransformer ();
	Tf.transform (new Domsource (document), New Streamresult (New FileOutputStream ("1.xml"));
}

4.Delete

private static void Delete (document document) throws exception{
	Node name = document.getElementsByTagName ("name"). Item (0);
	Name.getparentnode (). removechild (name);
	Transformerfactory tfactory = Transformerfactory.newinstance ();
	Transformer tf = Tfactory.newtransformer ();
	Tf.transform (new Domsource (document), New Streamresult (New FileOutputStream ("1.xml"));
}