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Java parsing XML document four kinds of effective methods

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XML has now become a general Data Interchange format, its platform independent, language-independent, system-independent, which brings great convenience to data integration and interaction. For the syntax knowledge and technical details of the XML itself, it is necessary to read the relevant technical literature, which includes the DOM (document Object Model), the DTD (document Type Definition), and SAX (simple APIs for XML), XSD (XML Schema Definition), XSLT (extensible Stylesheet Language Transformations), refer to the official web site documentation http:// www.w3.org get more information.

XML is interpreted in the same way in different languages, except that the syntax of the implementation is different. There are two basic parsing methods, one called Sax and the other called Dom. Sax is based on parsing of event streams, and Dom is based on XML document tree structure parsing. Suppose the content and structure of our XML are as follows:


<?xml version= "1.0" encoding= "UTF-8"?>
<employees>
<employee>
<name>ddviplinux</name>
<sex>m</sex>
<age>30</age>
</employee>
</employees>

This article uses the Java language to implement the XML document generation and parsing of Dom and sax.
First, define an interface for manipulating XML documents XmlDocument it defines an interface for establishing and parsing XML documents.

Package Com.alisoft.facepay.framework.bean;
/**
*
* @author HONGLIANG.DINGHL
* Defines an interface for XML document creation and resolution
*/
Public interface XmlDocument {
/**
* Create an XML document
* @param filename File full path name
*/
public void Createxml (String fileName);
/**
* Parse XML document
* @param filename File full path name
*/
public void Parserxml (String fileName);
}

1.DOM Generating and parsing XML documents

Defines a set of interfaces for the parsed version of an XML document. The parser reads the entire document and then constructs a tree that resides in memory, and then the code can manipulate the tree structure using the DOM interface. Advantage: The entire document tree is in memory, easy to operate, support delete, modify, rearrange and so on a variety of functions; disadvantages: The entire document into memory (including useless nodes), waste of time and space; usage: Once the document is parsed, the data needs to be accessed more than once; hardware resources are sufficient (memory, CPU).

Package Com.alisoft.facepay.framework.bean;
Import Java.io.FileInputStream;
Import java.io.FileNotFoundException;
Import Java.io.FileOutputStream;
Import java.io.IOException;
Import Java.io.InputStream;
Import Java.io.PrintWriter;
Import Javax.xml.parsers.DocumentBuilder;
Import Javax.xml.parsers.DocumentBuilderFactory;
Import javax.xml.parsers.ParserConfigurationException;
Import Javax.xml.transform.OutputKeys;
Import Javax.xml.transform.Transformer;
Import javax.xml.transform.TransformerConfigurationException;
Import javax.xml.transform.TransformerException;
Import Javax.xml.transform.TransformerFactory;
Import Javax.xml.transform.dom.DOMSource;
Import Javax.xml.transform.stream.StreamResult;
Import org.w3c.dom.Document;
Import org.w3c.dom.Element;
Import Org.w3c.dom.Node;
Import org.w3c.dom.NodeList;
Import org.xml.sax.SAXException;
/**
*
* @author HONGLIANG.DINGHL
* Dom Generation and parsing XML documents
*/
Public class Domdemo implements XmlDocument {
Private document document;
Private String FileName;
public void init () {
try {
Documentbuilderfactory factory = Documentbuilderfactory
. newinstance ();
Documentbuilder builder = Factory.newdocumentbuilder ();
This.document = Builder.newdocument ();
catch (Parserconfigurationexception e) {
System.out.println (E.getmessage ());
}
}
public void Createxml (String fileName) {
Element root = this.document.createElement ("Employees");
This.document.appendChild (root);
Element employee = this.document.createElement ("employee");
Element name = this.document.createElement ("name");
Name.appendchild ("ding-this.document.createTextNode");
Employee.appendchild (name);
Element sex = this.document.createElement ("Sex");
Sex.appendchild (This.document.createTextNode ("M"));
Employee.appendchild (Sex);
Element age = this.document.createElement (' age ');
Age.appendchild (This.document.createTextNode ("30"));
Employee.appendchild (age);
Root.appendchild (employee);
Transformerfactory tf = Transformerfactory.newinstance ();
try {
Transformer Transformer = Tf.newtransformer ();
Domsource Source = new Domsource (document);
Transformer.setoutputproperty (outputkeys.encoding, "gb2312");
Transformer.setoutputproperty (outputkeys.indent, "yes");
PrintWriter pw = new PrintWriter (new FileOutputStream (FileName));
Streamresult result = new Streamresult (PW);
Transformer.transform (source, result);
SYSTEM.OUT.PRINTLN ("Generate XML File Success!");
catch (Transformerconfigurationexception e) {
System.out.println (E.getmessage ());
catch (IllegalArgumentException e) {
System.out.println (E.getmessage ());
catch (FileNotFoundException e) {
System.out.println (E.getmessage ());
catch (Transformerexception e) {
System.out.println (E.getmessage ());
}
}
public void Parserxml (String fileName) {
try {
Documentbuilderfactory dbf = Documentbuilderfactory.newinstance ();
Documentbuilder db = Dbf.newdocumentbuilder ();
Document document = Db.parse (FileName);
NodeList employees = Document.getchildnodes ();
for (int i = 0; i < employees.getlength (); i++) {
Node employee = Employees.item (i);
NodeList EmployeeInfo = Employee.getchildnodes ();
for (int j = 0; J < Employeeinfo.getlength (); j + +) {
Node node = Employeeinfo.item (j);
NodeList Employeemeta = Node.getchildnodes ();
for (int k = 0; k < employeemeta.getlength (); k++) {
System.out.println (Employeemeta.item (k). Getnodename ()
+ ":" + Employeemeta.item (k). Gettextcontent ());
}
}
}
System.out.println ("Parse complete");
catch (FileNotFoundException e) {
System.out.println (E.getmessage ());
catch (Parserconfigurationexception e) {
System.out.println (E.getmessage ());
catch (Saxexception e) {
System.out.println (E.getmessage ());
catch (IOException e) {
System.out.println (E.getmessage ());
}
}
}


2.SAX Generating and parsing XML documents

Sax appears to solve the DOM problem. SAX, event-driven. When the parser discovers the start of the element, the end of the element, the text, the beginning or the end of the document, send the event, the programmer writes the code that responds to the events, and saves the data. Advantages: Without the prior transfer of the entire document, less resources; The SAX parser code is smaller than the DOM parser code, suitable for applets, downloads. Disadvantage: not lasting; After the event, if the data is not saved, then the data is lost; stateless; only the text can be obtained from the event, but it is not known which element the text belongs to; usage: Applet; only a small amount of content in an XML document;

Java code

The code is as follows Copy Code

Package Com.alisoft.facepay.framework.bean;
Import Java.io.FileInputStream;
Import java.io.FileNotFoundException;
Import java.io.IOException;
Import Java.io.InputStream;

Import javax.xml.parsers.ParserConfigurationException;
Import Javax.xml.parsers.SAXParser;
Import Javax.xml.parsers.SAXParserFactory;

Import org.xml.sax.Attributes;
Import org.xml.sax.SAXException;
Import Org.xml.sax.helpers.DefaultHandler;
/**
*
* @author HONGLIANG.DINGHL
* Sax Document parsing
*/
Public class Saxdemo implements XmlDocument {

public void Createxml (String fileName) {
System.out.println ("<<" +filename+ ">>");
}

public void Parserxml (String fileName) {
SAXParserFactory SAXFAC = Saxparserfactory.newinstance ();

try {

SAXParser saxparser = Saxfac.newsaxparser ();

InputStream is = new FileInputStream (fileName);

Saxparser.parse (IS, new Mysaxhandler ());

catch (Parserconfigurationexception e) {

E.printstacktrace ();

catch (Saxexception e) {

E.printstacktrace ();

catch (FileNotFoundException e) {

E.printstacktrace ();

catch (IOException e) {

E.printstacktrace ();

}

}

}

Class Mysaxhandler extends DefaultHandler {

Boolean hasattribute = false;

Attributes Attributes = null;

public void Startdocument () throws Saxexception {

System.out.println ("document started printing");

}

public void Enddocument () throws Saxexception {

System.out.println ("End of document Printing");

}

public void Startelement (string uri, String localname, String qName,

Attributes Attributes) throws Saxexception {

if (Qname.equals ("Employees")) {

Return

}

if (Qname.equals ("employee")) {

System.out.println (QName);

}

if (attributes.getlength () > 0) {

this.attributes = attributes;

This.hasattribute = true;

}

}

public void EndElement (string uri, String localname, String qName)

Throws Saxexception {

if (Hasattribute && (attributes!= null)) {

for (int i = 0; i < attributes.getlength (); i++) {

System.out.println (attributes.getqname (0)
+ attributes.getvalue (0));

}

}

}

public void characters (char[] ch, int start, int length)

Throws Saxexception {

System.out.println (New String (CH, start, length));

}

}
Package Com.alisoft.facepay.framework.bean;
Import Java.io.FileInputStream;
Import java.io.FileNotFoundException;
Import java.io.IOException;
Import Java.io.InputStream;
Import javax.xml.parsers.ParserConfigurationException;
Import Javax.xml.parsers.SAXParser;
Import Javax.xml.parsers.SAXParserFactory;
Import org.xml.sax.Attributes;
Import org.xml.sax.SAXException;
Import Org.xml.sax.helpers.DefaultHandler;
/**
*
* @author HONGLIANG.DINGHL
* Sax Document parsing
*/
Public class Saxdemo implements XmlDocument {
public void Createxml (String fileName) {
System.out.println ("<<" +filename+ ">>");
}
public void Parserxml (String fileName) {
SAXParserFactory SAXFAC = Saxparserfactory.newinstance ();
try {
SAXParser saxparser = Saxfac.newsaxparser ();
InputStream is = new FileInputStream (fileName);
Saxparser.parse (IS, new Mysaxhandler ());
catch (Parserconfigurationexception e) {
E.printstacktrace ();
catch (Saxexception e) {
E.printstacktrace ();
catch (FileNotFoundException e) {
E.printstacktrace ();
catch (IOException e) {
E.printstacktrace ();
}
}
}
Class Mysaxhandler extends DefaultHandler {
Boolean hasattribute = false;
Attributes Attributes = null;
public void Startdocument () throws Saxexception {
System.out.println ("document started printing");
}
public void Enddocument () throws Saxexception {
System.out.println ("End of document Printing");
}
public void Startelement (string uri, String localname, String qName,
Attributes Attributes) throws Saxexception {
if (Qname.equals ("Employees")) {
Return
}
if (Qname.equals ("employee")) {
System.out.println (QName);
}
if (attributes.getlength () > 0) {
this.attributes = attributes;
This.hasattribute = true;
}
}
public void EndElement (string uri, String localname, String qName)
Throws Saxexception {
if (Hasattribute && (attributes!= null)) {
for (int i = 0; i < attributes.getlength (); i++) {
System.out.println (attributes.getqname (0)
+ attributes.getvalue (0));
}
}
}
public void characters (char[] ch, int start, int length)
Throws Saxexception {
System.out.println (New String (CH, start, length));
}
}


3.DOM4J generate and parse XML documents

Dom4j is a very, very good Java XML API with excellent performance, powerful features and extreme ease of use, and it is also an open-source software. Now you can see that more and more Java software is using dom4j to read and write XML, and it is particularly worth mentioning that even Sun's JAXM is using DOM4J.

Java code

The code is as follows Copy Code

Package Com.alisoft.facepay.framework.bean;
Import Java.io.File;
Import Java.io.FileWriter;
Import java.io.IOException;
Import Java.io.Writer;
Import Java.util.Iterator;

Import org.dom4j.document;  
Import org.dom4j.documentexception;  
Import org.dom4j.documenthelper;  
Import org.dom4j.element;  
Import Org.dom4j.io.SAXReader;   
Import org.dom4j.io.xmlwriter;  
/** 
*  
* @author HONGLIANG.D inghl 
* dom4j generate XML documents and parse XML documents  
*/ 
public class Dom4jdemo implements XmlDocument {&NBSP;&NB SP;

public void Createxml (String fileName) {
Document document = Documenthelper.createdocument ();
Element employees=document.addelement ("Employees");
Element employee=employees.addelement ("employee");
Element name= employee.addelement ("name");
Name.settext ("Ddvip");
Element sex=employee.addelement ("sex");
Sex.settext ("M");
Element age=employee.addelement ("Age");
Age.settext ("29");
try {
Writer filewriter=new FileWriter (fileName);
XMLWriter xmlwriter=new XMLWriter (fileWriter);
Xmlwriter.write (document);
Xmlwriter.close ();
catch (IOException e) {

System.out.println (E.getmessage ());
}


}


public void Parserxml (String fileName) {
File Inputxml=new file (fileName);
Saxreader Saxreader = new Saxreader ();
try {
Document document = Saxreader.read (Inputxml);
Element employees=document.getrootelement ();
for (Iterator i = Employees.elementiterator (); I.hasnext ();) {
Element employee = (Element) I.next ();
for (Iterator J = employee.elementiterator (); J.hasnext ();) {
Element node= (Element) J.next ();
System.out.println (Node.getname () + ":" +node.gettext ());
}

}
catch (Documentexception e) {
System.out.println (E.getmessage ());
}
System.out.println ("dom4j parserxml");
}
}

4.JDOM Generating and parsing xml

To reduce the number of DOM, Sax coding, there are jdom, advantages: 20-80 principles, greatly reducing the amount of code. Usage: Simple to implement, such as parsing, creating, but at the bottom, Jdom still uses sax (most commonly used), DOM, Xanan documents.

The code is as follows Copy Code



Package Com.alisoft.facepay.framework.bean;

Import java.io.FileNotFoundException;
Import Java.io.FileOutputStream;
Import java.io.IOException;
Import java.util.List;

Import org.jdom.Document;
Import org.jdom.Element;
Import org.jdom.JDOMException;
Import Org.jdom.input.SAXBuilder;
Import Org.jdom.output.XMLOutputter;
/**
*
* @author HONGLIANG.DINGHL
* JDOM generate and parse XML documents
*
*/
Public class Jdomdemo implements XmlDocument {

public void Createxml (String fileName) {
Document document;
Element Root;
Root=new Element ("Employees");
Document=new Document (root);
Element employee=new Element ("employee");
Root.addcontent (employee);
Element name=new Element ("name");
Name.settext ("Ddvip");
Employee.addcontent (name);
Element sex=new element ("sex");
Sex.settext ("M");
Employee.addcontent (Sex);
Element age=new Element ("age");
Age.settext ("23");
Employee.addcontent (age);
Xmloutputter xmlout = new Xmloutputter ();
try {
Xmlout.output (document, New FileOutputStream (FileName));
catch (FileNotFoundException e) {
E.printstacktrace ();
catch (IOException e) {
E.printstacktrace ();
}

}

public void Parserxml (String fileName) {
Saxbuilder builder=new Saxbuilder (false);
try {
Document Document=builder.build (fileName);
Element employees=document.getrootelement ();
List Employeelist=employees.getchildren ("employee");
for (int i=0;i<employeelist. SIZE (); i++) {
Element employee= (Element) employeelist.get (i);
List Employeeinfo=employee.getchildren ();
for (int j=0;j<employeeinfo. SIZE (); J + +) {
System.out.println ((Element) Employeeinfo.get (j)). GetName () + ":" + ((Element) Employeeinfo.get (j)). GetValue ());

}
}
catch (Jdomexception e) {

E.printstacktrace ();
catch (IOException e) {

E.printstacktrace ();
}

}
}

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

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