Création d'un fichier XML en Java (compatible avec DAO)

Bonjour,

je suis entrain de travailler avec le pattern DAO dans Java (séparation entre la classe métier et la classe d'accès à la base de données) pour fouiller dans la base de données. je souhaite maintenant créer un fichier XML à partir des résultats générés grâce ce pattern DAO.
Comment serait-il possible de faire cela ?!

Bonjour,

J'ai cherché un petit temps pour une DAO XML toute faite mais force est de constater qu'il n'y a pas d'exemples concrets en la matière.

Ce que je propose c'est de créer une interface:

Code:

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public interface ArticleDAO { public int insertArticle(...); public Article findArticle(...); public boolean updateArticle(...); public boolean deleteArticle(...); ... }

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Ensuite implémentes l'interface avec une classe que l'on pourrait appeler ArticleDAOXML. Dans cette DAO on pourrait ajouter un String ou File pour indiquer le chemin où écrire les fichiers XML.

Pour finir, ajoutes le framework XStream ( http://xstream.codehaus.org/ ) dans to build path pour sérialiser des objets sous forme de fichier XML et remplir les méthodes selon ta convenance. Il y a un tutoriel ici: http://xstream.codehaus.org/tutorial.html

Il faut crée un Pojo des tables de ta base de données, ensuite tu crée l'interface dao qui va comprendre les méthodes de requête SQL que tu désire appliquer, et tu les définis dans la classe dao qui implémente l'interface.

Si tu t'arrête à ça et que tu veut maintenant générer les xml, faut utiliser un framework qui générera ton xml (Castor par exemple).

Bonjour,

Pour ceux que ça intéresse, il y a un tuto très bien fait sur le pattern DAO ici. Son auteur est de BallusC.

J'ai réalisé la partie XML du DAO de ce tuto que voici.

Voici la classe "UserDAOXML" qui fait un usage intensif de XPath et de XStream.

Code:

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package com.example.dao;   import java.io.File; import java.io.StringReader; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.ArrayList; import java.util.List;   import javax.xml.namespace.QName; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.transform.Transformer; import javax.xml.transform.TransformerFactory; import javax.xml.transform.dom.DOMSource; import javax.xml.transform.stream.StreamResult; import javax.xml.xpath.XPath; import javax.xml.xpath.XPathConstants; import javax.xml.xpath.XPathExpression; import javax.xml.xpath.XPathExpressionException; import javax.xml.xpath.XPathFactory;   import org.w3c.dom.Document; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.xml.sax.InputSource;   import com.example.model.User;   public class UserDAOXML implements UserDAO {   // Constants // ----------------------------------------------------------------------------------   private static final String XPATH_FIND_BY_ID = "//user[id=$id]"; private static final String XPATH_FIND_BY_EMAIL_AND_PASSWORD = "//user[email=$email and password=$password]"; private static final String XPATH_LIST = "//user"; private static final String XPATH_UPDATE = "//user[id=$id]"; private static final String XPATH_DELETE = "//user[id=$id]"; private static final String XPATH_EXIST_EMAIL = "//user[email=$email]"; private static final String XPATH_CHANGE_PASSWORD = "//user[id=$id]/password"; private static final String XPATH_MAX_VALUE = "//user/id";   // Vars // ---------------------------------------------------------------------------------------   private File xmlFile = null; private DAOFactory daoFactory = null;   // Constructors // -------------------------------------------------------------------------------   public UserDAOXML(DAOFactory daoFactory) { // Getting the XML file name at the initialization this.xmlFile = new File("C:/Temp.", "users.xml"); this.daoFactory = daoFactory; }   // Actions // ------------------------------------------------------------------------------------   public User find(Long id) throws DAOException {   try { // Checking if the file exist if (xmlFile.exists()) { // Use the standard org.w3c.dom APIs to get a DOM. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); Document document = dbf.newDocumentBuilder().parse(xmlFile);   // Getting the user SimpleVariableResolver resolver = new SimpleVariableResolver(); resolver.addVariable(new QName(null, "id"), id); XPath xPath = XPathFactory.newInstance().newXPath(); xPath.setXPathVariableResolver(resolver); XPathExpression xpe = xPath.compile(XPATH_FIND_BY_ID); Node userNode = (Node) xpe.evaluate(document, XPathConstants.NODE);   User user = mapUser(userNode);   return user; }   } catch (Exception ex) { throw new DAOException(ex); }   return null; }   public User find(String email, String password) throws DAOException {   try { // Checking if the file exist if (xmlFile.exists()) { // Use the standard org.w3c.dom APIs to get a DOM. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); Document document = dbf.newDocumentBuilder().parse(xmlFile);   // Getting the user SimpleVariableResolver resolver = new SimpleVariableResolver(); resolver.addVariable(new QName(null, "email"), email); resolver.addVariable(new QName(null, "password"), password); XPath xPath = XPathFactory.newInstance().newXPath(); xPath.setXPathVariableResolver(resolver); XPathExpression xpe = xPath.compile(XPATH_FIND_BY_EMAIL_AND_PASSWORD); Node userNode = (Node) xpe.evaluate(document, XPathConstants.NODE);   User user = mapUser(userNode);   return user; }   } catch (Exception ex) { throw new DAOException(ex); }   return null; }   public List<User> list() throws DAOException {   try { // Checking if the file exist if (xmlFile.exists()) { // Use the standard org.w3c.dom APIs to get a DOM. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); Document document = dbf.newDocumentBuilder().parse(xmlFile);   // Getting all users XPath xPath = XPathFactory.newInstance().newXPath(); XPathExpression xpe = xPath.compile(XPATH_LIST); NodeList listUserNode = (NodeList) xpe.evaluate(document, XPathConstants.NODESET);   List<User> listUser = new ArrayList<User>();   // Iterate through all users for (int i = 0; i < listUserNode.getLength(); i++) { Node userNode = listUserNode.item(i);   User user = mapUser(userNode);   listUser.add(user); }   return listUser; }   } catch (Exception ex) { throw new DAOException(ex); }   return null; }   public void create(User user) throws IllegalArgumentException, DAOException {   try { UserXMLTransformer xmlTransformer = new UserXMLTransformer();   // Checking if the file exist if (!xmlFile.exists()) { // If file does not exist in the database path, create and store // an empty User node xmlTransformer.writeFile(xmlFile, new ArrayList<User>()); }   // Create the XML document by loading the file List<User> listUser = xmlTransformer.xmlToObject(xmlFile);   // Getting the maximum Id based on the XML data already stored String xml = xmlTransformer.objectToXml(listUser); long maxId = getMaxValue(xml);   // Adding Id column. Auto generated column user.setId(maxId + 1);   listUser.add(user);   // Saving the file after adding the new user node xmlTransformer.writeFile(xmlFile, listUser);   } catch (XPathExpressionException ex) { throw new DAOException(ex); } }   public void update(User user) throws IllegalArgumentException, DAOException {   try { // Checking if the file exist if (xmlFile.exists()) { // Use the standard org.w3c.dom APIs to get a DOM. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); Document document = dbf.newDocumentBuilder().parse(xmlFile);   // Then get the node using the standard javax.xml.xpath APIs. SimpleVariableResolver resolver = new SimpleVariableResolver(); resolver.addVariable(new QName(null, "id"), user.getId()); XPath xPath = XPathFactory.newInstance().newXPath(); xPath.setXPathVariableResolver(resolver); XPathExpression xpe = xPath.compile(XPATH_UPDATE); Node userNode = (Node) xpe.evaluate(document, XPathConstants.NODE);   if (userNode != null) { userNode = updateNode(userNode, user);   // And then use the javax.xml.transform APIs to write it // back out. TransformerFactory tf = TransformerFactory.newInstance(); Transformer transformer = tf.newTransformer(); transformer.transform(new DOMSource(document), new StreamResult(xmlFile)); }   } else { throw new Exception("Database file does not exist in the folder"); }   } catch (Exception ex) { throw new DAOException(ex); } }   public void delete(User user) throws DAOException {   try { // Checking if the file exist if (xmlFile.exists()) { // Use the standard org.w3c.dom APIs to get a DOM. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); Document document = dbf.newDocumentBuilder().parse(xmlFile);   // Then get the node using the standard javax.xml.xpath APIs. SimpleVariableResolver resolver = new SimpleVariableResolver(); resolver.addVariable(new QName(null, "id"), user.getId()); XPath xPath = XPathFactory.newInstance().newXPath(); xPath.setXPathVariableResolver(resolver); XPathExpression xpe = xPath.compile(XPATH_DELETE); Node userNode = (Node) xpe.evaluate(document, XPathConstants.NODE);   if (userNode != null) { userNode.getParentNode().removeChild(userNode);   // And then use the javax.xml.transform APIs to write it // back out. TransformerFactory tf = TransformerFactory.newInstance(); Transformer transformer = tf.newTransformer(); transformer.transform(new DOMSource(document), new StreamResult(xmlFile)); }   } else { throw new Exception("Database file does not exist in the folder"); }   } catch (Exception ex) { throw new DAOException(ex); } }   public boolean existEmail(String email) throws DAOException {   try { // Checking if the file exist if (xmlFile.exists()) { // Use the standard org.w3c.dom APIs to get a DOM. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); Document document = dbf.newDocumentBuilder().parse(xmlFile);   // Getting the user SimpleVariableResolver resolver = new SimpleVariableResolver(); resolver.addVariable(new QName(null, "email"), email); XPath xPath = XPathFactory.newInstance().newXPath(); xPath.setXPathVariableResolver(resolver); XPathExpression xpe = xPath.compile(XPATH_EXIST_EMAIL); Node userNode = (Node) xpe.evaluate(document, XPathConstants.NODE);   return (userNode != null) ? true : false; }   } catch (Exception ex) { throw new DAOException(ex); }   return false; }   public void changePassword(User user) throws DAOException {   try { // Checking if the file exist if (xmlFile.exists()) { // Use the standard org.w3c.dom APIs to get a DOM. DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); Document document = dbf.newDocumentBuilder().parse(xmlFile);   // Then get the node using the standard javax.xml.xpath APIs. SimpleVariableResolver resolver = new SimpleVariableResolver(); resolver.addVariable(new QName(null, "id"), user.getId()); XPath xPath = XPathFactory.newInstance().newXPath(); xPath.setXPathVariableResolver(resolver); XPathExpression xpe = xPath.compile(XPATH_CHANGE_PASSWORD); Node passwordNode = (Node) xpe.evaluate(document, XPathConstants.NODE);   if (passwordNode != null) { passwordNode.setTextContent(user.getPassword());   // And then use the javax.xml.transform APIs to write it // back out. TransformerFactory tf = TransformerFactory.newInstance(); Transformer transformer = tf.newTransformer(); transformer.transform(new DOMSource(document), new StreamResult(xmlFile)); }   } else { throw new Exception("Database file does not exist in the folder"); }   } catch (Exception ex) { throw new DAOException(ex); } }   private long getMaxValue(String xml) throws XPathExpressionException { long maxId = 0;   InputSource source = new InputSource(new StringReader(xml));   XPath xPath = XPathFactory.newInstance().newXPath(); XPathExpression xpe = xPath.compile(XPATH_MAX_VALUE); NodeList listUserNode = (NodeList) xpe.evaluate(source, XPathConstants.NODESET);   for (int i = 0; i < listUserNode.getLength(); i++) { Node employeeIdNode = listUserNode.item(i); String strId = employeeIdNode.getTextContent(); long id = Long.parseLong(strId); maxId = (id > maxId) ? id : maxId; }   return maxId; }   private Node updateNode(Node userNode, User user) {   // Iterate through all properties of an employee NodeList children = userNode.getChildNodes(); for (int j = 0; j < children.getLength(); j++) { Node node = children.item(j);   if (node.getNodeName().equals("email")) { node.setTextContent(user.getEmail()); } else if (node.getNodeName().equals("password")) { node.setTextContent(user.getPassword()); } else if (node.getNodeName().equals("firstname")) { node.setTextContent(user.getFirstname()); } else if (node.getNodeName().equals("lastname")) { node.setTextContent(user.getLastname()); } else if (node.getNodeName().equals("birthdate")) { node.setTextContent((new SimpleDateFormat("yyyy-MM-dd HH:mm:ss z")).format(user.getBirthdate())); } }   return userNode; }   private User mapUser(Node userNode) throws ParseException { User user = new User();   // Iterate through all properties of a user NodeList children = userNode.getChildNodes(); for (int j = 0; j < children.getLength(); j++) { Node node = children.item(j);   if (node.getNodeName().equals("id")) { user.setId(Long.parseLong(node.getTextContent())); } else if (node.getNodeName().equals("email")) { user.setEmail(node.getTextContent()); } else if (node.getNodeName().equals("password")) { user.setPassword(node.getTextContent()); } else if (node.getNodeName().equals("firstname")) { user.setFirstname(node.getTextContent()); } else if (node.getNodeName().equals("lastname")) { user.setLastname(node.getTextContent()); } else if (node.getNodeName().equals("birthdate")) { user.setBirthdate(new SimpleDateFormat("yyyy-MM-dd").parse(node.getTextContent())); } }   return user; } }

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Et la classe utilitaire correspondante "UserXMLTransformer":

Code:

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package com.example.dao;   import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.FileReader; import java.util.List;   import com.example.model.User; import com.thoughtworks.xstream.XStream; import com.thoughtworks.xstream.io.xml.StaxDriver;   public class UserXMLTransformer {   /* Xml to Object */ public List<User> xmlToObject(File xmlFile) { XStream xstream = new XStream(new StaxDriver()); configure(xstream);   List<User> listUser = null; try { FileReader fr = new FileReader(xmlFile); listUser = (List<User>) xstream.fromXML(fr); } catch (FileNotFoundException e) { System.out.println("FileNotFoundException Occured " + e.getMessage()); } return listUser; }   /* Object to Xml */ public String objectToXml(List<User> listUser) { XStream xstream = new XStream(); configure(xstream);   return xstream.toXML(listUser); }   /* Write Object into file */ public void writeFile(File file, List<User> listUser) { try { XStream xstream = new XStream(); configure(xstream);   FileOutputStream fs = new FileOutputStream(file); xstream.toXML(listUser, fs);   } catch (FileNotFoundException e) { e.printStackTrace(); } }   private void configure(XStream xstream) { xstream.alias("user", User.class); xstream.alias("users", List.class); } }

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Et la classe SimpleVariableResolver:

Code:

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package com.example.dao;   import java.util.HashMap; import java.util.Map;   import javax.xml.namespace.QName; import javax.xml.xpath.XPathVariableResolver;   public class SimpleVariableResolver implements XPathVariableResolver {   private static final Map<QName, Object> vars = new HashMap<QName, Object>();   public void addVariable(QName name, Object value) { vars.put(name, value); }   public Object resolveVariable(QName name) { return vars.get(name); } }

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La classe "DAOFactoryXML":

Code:

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package com.example.dao;   import java.sql.Connection; import java.sql.SQLException;   public abstract class DAOFactoryXML implements DAOFactory {   public static DAOFactory getInstance() throws DAOConfigurationException { return new XMLDAOFactory(); }   abstract Connection getConnection() throws SQLException;   public UserDAO getUserDAO() { return new UserDAOXML(this); } }   class XMLDAOFactory extends DAOFactoryXML { @Override Connection getConnection() throws SQLException { return null; } }

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et la classe "ServiceImpl":

Code:

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package com.example.service;   import java.util.List;   import com.example.dao.DAOFactoryJDBC; import com.example.dao.DAOFactoryXML; import com.example.dao.DAOFactory; import com.example.model.User;   public class ServiceImpl<T> implements Service<User> {   private String mode = null;   public ServiceImpl(String mode) { this.mode = mode; }   private DAOFactory getDOAFactory() { if ("JDBC".equals(mode)) return DAOFactoryJDBC.getInstance("javabase.jdbc"); else if ("XML".equals(mode)) return DAOFactoryXML.getInstance(); else return null; }   public void create(User object) { getDOAFactory().getUserDAO().create(object); }   public void delete(User object) { getDOAFactory().getUserDAO().delete(object); }   public void update(User object) { getDOAFactory().getUserDAO().update(object); }   public List<User> list() { return getDOAFactory().getUserDAO().list(); }   public boolean existEmail(String email) { return getDOAFactory().getUserDAO().existEmail(email); }   public void changePassword(User object) { getDOAFactory().getUserDAO().changePassword(object); }   public User find(String email, String password) { return getDOAFactory().getUserDAO().find(email, password); }   }

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Cordialement.