XML Replace DB operate (SELECT, delete, add, update) __xml

Application construct:Xmldemo:-Src-com.djh.michael.bean

-User.java

-Com.djh.michael.dao

-Xmldao.java-com.djh.michael.utils

-Xmlutils.java

-Com.djh.michael.exception

-Useralreadyexists.java

-Usernotfoundexception.java

-Com.djh.michael.test

-Testcase.java JavaBean:User.java

Package Com.djh.michael.bean;
	public class User {private String ID;
	private String name;
	private int age;
	Private String currency;
	private int quality;

	private double price;
		Public User () {super ();
			TODO auto-generated Constructor stub} public User (string ID, string name, int age, string currency, int quality,
		Double price) {super ();
		This.id = ID;
		THIS.name = name;
		This.age = age;
		this.currency = currency;
		this.quality = quality;
	This.price = Price;
	Public String GetId () {return id;
	public void SetId (String id) {this.id = ID;
	Public String GetName () {return name;
	public void SetName (String name) {this.name = name;
	public int getage () {return age;
	public void Setage (int age) {this.age = age;
	Public String getcurrency () {return currency;
	} public void Setcurrency (String currency) {this.currency = currency;
	public int getquality () {return quality; } public void setquality (int quality) {
		this.quality = quality;
	Public double GetPrice () {return price;
	public void Setprice (double price) {this.price = Price; @Override public String toString () {return "User [id=] + ID +", name= "+ name +", age= "+ Age +", currency=
	"+ Currency +", quality= "+ quality +", price= "+ price +"];
 }
}

DAO:XmlDAO.java

Package Com.djh.michael.dao;
Import java.util.ArrayList;
Import Java.util.Iterator;

Import java.util.List;
Import org.dom4j.Document;
Import org.dom4j.DocumentException;
Import org.dom4j.Element;

Import Org.dom4j.Node;
Import Com.djh.michael.bean.User;
Import com.djh.michael.exception.UserAlreadyExists;
Import com.djh.michael.exception.UserNotFoundException;

Import Com.djh.michael.utils.XmlUtils;
	public class Xmldao {String path = ' Src/users.xml ';
	Private user user = null;
	Select one data.
			Public User Getoneuser (String id) {try {//get the Document object via class of Utils.
			Document document = Xmlutils.getdocument (path);
			Element rootelement = Document.getrootelement ();
			Select the one record via field of ID.
			list<element> list = Rootelement.selectnodes ("/users/user[id=" + ID + "]/*");
			if (list!= null) {user = new user ();
			} setUser (list, user);
		return user;
		catch (Documentexception e) {e.printstacktrace ();
	return null; }
	
	Get all users data.
		Public list<user> Getalluser () {list<user> List = new arraylist<user> ();
			try {Document document = Xmlutils.getdocument (path);
			Element rootelement = Document.getrootelement ();
			Via Xpath expression to select all the nodes.
			list<element> nodes = rootelement.selectnodes ("/users/*");
				for (int i = 0; Nodes!=null && i < nodes.size (); i++) {User user = new user ();
				list<element> usernodes = Nodes.get (i) selectnodes ("/users/user[" + (i + 1) + "]/*");
				SetUser (usernodes, user);
			List.add (user);
		} catch (Documentexception e) {e.printstacktrace ();
	} return list;
		public boolean addUser (user user) {Boolean result = false;
			Try {//get the object of document.
			Document document = Xmlutils.getdocument (path);
			Element root = Document.getrootelement ();
			Judge the user whether if already exists. Node node = root.selectsinglenode ("/users/user[id=" + user.getid () + "]");
			if (node!= null) {System.out.println ("User is already exists ...");
			throw new Useralreadyexists ("User is already exists ...");
			}//add the user element.
			Element userelement = root.addelement ("user");
			Userelement.addelement ("id"). addtext (User.getid ());
			Userelement.addelement ("name"). AddText (User.getname ());
			Via add empty character to transfer the none string to string type.
			Userelement.addelement ("Age"). AddText (User.getage () + "");
			Userelement.addelement ("Currency"). AddText (User.getcurrency ());
			Userelement.addelement ("Quality"). AddText (user.getquality () + "");
			Userelement.addelement ("Price"). AddText (User.getprice () + "");
			Write to file.
			Xmlutils.write2document (path, document);
			System.out.println ("Add user success ...");
		result = true;
		}catch (useralreadyexists e) {throw new RuntimeException (e);
		catch (Exception e) {e.printstacktrace ();
	return result; public boolean updateuser (user user) {Boolean result = FalsE
			try {//get the Document Object document = Xmlutils.getdocument (path);
			Element root = Document.getrootelement ();
			Find there whether if exists user which ready update.
			Node node = root.selectsinglenode ("/users/user[id=" + user.getid () + "]");
				if (node = = null) {System.out.println ("User not exists ...");
			throw new Usernotfoundexception ("The user is not exists which ID is" + user.getid ());
			} list<element> List = Root.selectnodes ("/users/user[id=" + user.getid () + "]/*");
			UpdateUser (list, user);
			Update xmlutils.write2document (path, document);
			SYSTEM.OUT.PRINTLN ("Update success ...");
		result = true;
		}catch (Usernotfoundexception e) {throw new RuntimeException (e);
		catch (Exception e) {e.printstacktrace ();
	return result;
		public boolean deleteuser (user user) {Boolean result = false;
			Try {//get the object of document.
			Document document = Xmlutils.getdocument (path); Element root = document.Getrootelement ();
			In there, you can select the What you like option to filter.
			Node node = root.selectsinglenode ("/users/user[id=" + user.getid () + "]");
			if (node = null) {throw new Usernotfoundexception ("User not found, please confirm ...");
			}//remove the user via itself ' s parent node.
			Node.getparent (). Remove (node);
			Write to file.
			Xmlutils.write2document (path, document);
			SYSTEM.OUT.PRINTLN ("Update success ...");
		result = true;
		}catch (Usernotfoundexception e) {throw new RuntimeException (e);
		}catch (Exception e) {e.printstacktrace ();
	return result; } private void SetUser (list<element> List, user user) {//via to loop all of the options for (iterator iter = Li St.iterator (); Iter.hasnext ();)
			{Node node = (Element) iter.next ();
			Get the element tag name and content String name = Node.getname ();
			
			String value = Node.gettext ();
			Package data to Bean object.
			if ("id". Equals (name)) {User.setid (value);
			}if ("Name". Equals (name)) {user.setname (value);
			} if ("Age". Equals (name)) {User.setage (Integer.parseint (value));
			} if ("Currency". Equals (name)) {user.setcurrency (value);
			} if ("Quality". Equals (name)) {user.setquality (Integer.parseint (value));
			} if ("Price". Equals (name)) {User.setprice (double.parsedouble (value));
		} System.out.println ("@@@" + name + ":" + value); } private void UpdateUser (list<element> List, user user) {//via to loop all the options for (iterator ite R = List.iterator (); Iter.hasnext ();)
			{Node node = (Element) iter.next ();
			Get the element tag name and content String name = Node.getname ();
			
			String value = Node.gettext ();
			Package data to Bean object.
			if ("id". Equals (name)) {Node.settext (User.getid ());
			} if ("Name". Equals (name)) {Node.settext (User.getname ());
			} if ("Age". Equals (name)) {Node.settext (User.getage () + ""); } if ("Currency". Equals (name)) {NODE.SEttext (User.getcurrency ());
			} if ("Quality". Equals (name)) {Node.settext (user.getquality () + "");
			} if ("Price". Equals (name)) {Node.settext (User.getprice () + "");
 }
		}
	}
}

Exception:UserAlreadyExists.java and Usernotfoundexception.javaJust extends Exception and method. Utils:XmlUtils.java

Package com.djh.michael.utils;
Import Java.io.FileOutputStream;
Import org.dom4j.Document;
Import org.dom4j.DocumentException;
Import Org.dom4j.io.OutputFormat;
Import Org.dom4j.io.SAXReader;
Import Org.dom4j.io.XMLWriter;

public class Xmlutils {public
	
	static Document getdocument (String path) throws documentexception{
		Saxreader reader = new Saxreader ();
		Document document = Reader.read (path);
		return document;
	}
	
	public static void Write2document (String path, document document) throws exception{
		//format the XML file
		OUTPU Tformat format = Outputformat.createprettyprint ();
		Format.setencoding ("Utf-8");
		XMLWriter writer = new XMLWriter (new FileOutputStream (path), format);
		Writer.write (document);
		Writer.close ();
	}

XML file (DB): Users.xml

<?xml version= "1.0" encoding= "Utf-8"?>
<users> 
  <user> 
    <id>123</id>  
    <name>djh</name>  
    <age>25</age>  
    <currency>USD</currency>  
    <quality>200</quality>  
    <price>12.25</price> 
  </user>  
  <user> 
    <id>456</id>  
    <name>tk</name>  
    <age>24</age>  
    < currency>aud</currency>  
    <quality>5000</quality>  
    <price>11.06</price > 
  </user>  
</users>

Class of Test:TestCase.java

Package com.djh.michael.test;
Import java.util.List;
Import Org.junit.Test;
Import Com.djh.michael.bean.User;

Import Com.djh.michael.dao.XmlDao;
		public class TestCase {@Test public void Testxmldaogetuser () {Xmldao Xmldao = new Xmldao ();
		User user = Xmldao.getoneuser ("123");
	System.out.println (User.tostring ());
		@Test public void Testgetalluser () {Xmldao Xmldao = new Xmldao ();
		list<user> list = Xmldao.getalluser ();
	SYSTEM.OUT.PRINTLN (list);
		@Test public void Testadduser () {User user = new User ("789", "LJ", "6000, 9.5");
		Xmldao Xmldao = new Xmldao ();
		Boolean result = Xmldao.adduser (user);
	SYSTEM.OUT.PRINTLN (result);
		@Test public void Testupdate () {User user = new User ("789", "Niu", "HKD", 6000, 9.5);
		Xmldao Xmldao = new Xmldao ();
		Boolean result = Xmldao.updateuser (user);
	SYSTEM.OUT.PRINTLN (result);
		@Test public void Testdeleteuser () {User user = new User ("789", "LJ", "6000, 9.5"); Xmldao Xmldao =New Xmldao ();
	Xmldao.deleteuser (user); }
	
}

Xpath Format Reference Link:

Http://www.w3schools.com/xml/xml_xpath.asp