La lecture d'un fichier XML en Java est très différente de la lecture d'autres fichiers comme .docx et .txt car le fichier XML contient des données entre les balises. Java propose de nombreuses façons d'analyser un fichier XML. Il existe deux analyseurs en Java qui analysent un fichier XML :
- Java DOMAINE Analyseur
- Java CORRECT Analyseur
Analyseur DOM Java
Le API DOM fournit les classes pour lire et écrire un fichier XML. Nous pouvons créer, supprimer, modifier et réorganiser le nœud à l'aide de l'API DOM. L'analyseur DOM analyse l'intégralité du fichier XML et crée un DOMAINE objet en mémoire. Il modélise un fichier XML dans un arborescence pour une traversée et une manipulation faciles. Dans DOM, tout ce qui se trouve dans un fichier XML est un nœud . Le nœud représente un composant d'un fichier XML. L'analyseur DOM est lent en cours et occupe beaucoup de mémoire lorsqu'il charge un fichier XML en mémoire.
Il faut avoir suivi la démarche pour lire un fichier XML en Java :
Étapes pour lire un fichier XML en Java à l'aide d'Eclipse
Étape 1: Créer un simple Java projet.
while et faire une boucle while en java
Étape 2: Créez un fichier de classe et fournissez un nom de fichier de classe. Nous avons créé le fichier de classe avec le nom LireXMLFichierExemple1 .
Étape 3: Écrivez le code suivant.
Étape 4: Télécharger dom-2.3.0-jaxb-1.0.6.jar déposer: Cliquez ici...
Étape 5 : Créer un lib dossier dans le projet.
Étape 6 : Copie dom-2.3.0-jaxb-1.0.6.jar fichier et collez-le dans le dossier lib.
Étape 7 : Met le chemin de classe :
quel est le numéro de l'alphabet
Faites un clic droit sur le projet->Build Path->Configure Build Path->Add External JARs->Sélectionnez le fichier JAR->cliquez sur le bouton Ouvrir->Appliquer et fermer.
Étape 8 : Créé un XML déposer. Nous avons créé un fichier XML avec le nom FichierXML.xml et écrivez-y les données suivantes.
Étape 9 : Exécutez le projet.
Création d'un fichier XML : FichierXML.xml
101 Naman Kumar Math 83 102 Kapil Kumar Chemistry 60 103 Harsh Singh English 70 104 Jitesh Singh Physics 76
Exemple de lecture d'un fichier XML à l'aide de DOM Parser
import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.DocumentBuilder; import org.w3c.dom.Document; import org.w3c.dom.NodeList; import org.w3c.dom.Node; import org.w3c.dom.Element; import java.io.File; public class ReadXMLFileExample1 { public static void main(String argv[]) { try { //creating a constructor of file class and parsing an XML file File file = new File('F:\XMLFile.xml'); //an instance of factory that gives a document builder DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance(); //an instance of builder to parse the specified xml file DocumentBuilder db = dbf.newDocumentBuilder(); Document doc = db.parse(file); doc.getDocumentElement().normalize(); System.out.println('Root element: ' + doc.getDocumentElement().getNodeName()); NodeList nodeList = doc.getElementsByTagName('student'); // nodeList is not iterable, so we are using for loop for (int itr = 0; itr <nodelist.getlength(); itr++) { node system.out.println(' node name :' + node.getnodename()); if (node.getnodetype()="=" node.element_node) element eelement="(Element)" node; system.out.println('student id: '+ eelement.getelementsbytagname('id').item(0).gettextcontent()); system.out.println('first name: eelement.getelementsbytagname('firstname').item(0).gettextcontent()); system.out.println('last eelement.getelementsbytagname('lastname').item(0).gettextcontent()); system.out.println('subject: eelement.getelementsbytagname('subject').item(0).gettextcontent()); system.out.println('marks: eelement.getelementsbytagname('marks').item(0).gettextcontent()); } catch (exception e) e.printstacktrace(); < pre> <p> <strong>Output:</strong> </p> <pre> Root element: class Node Name: student Student id: 101 First Name: Naman Last Name: Kumar Subject: Math Marks: 83 Node Name: student Student id: 102 First Name: Kapil Last Name: Kumar Subject: Chemistry Marks: 60 Node Name: student Student id: 103 First Name: Harsh Last Name: Singh Subject: English Marks: 70 Node Name: student Student id: 104 First Name: Jitesh Last Name: Singh Subject: Physics Marks: 76 </pre> <p>Let's see another example of reading xml file.</p> <p> <strong>Example of reading XML file using DOM Parser</strong> </p> <p>The following example reads the same XML file <strong>XMLFile.xml</strong> , and showing that how to loop the node one by one. It prints the node value, name and attribute if any.</p> <p> <strong>Example</strong> </p> <pre> import java.io.File; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import org.w3c.dom.Document; import org.w3c.dom.NamedNodeMap; import org.w3c.dom.Node; import org.w3c.dom.NodeList; public class ReadXMLFileExample2 { public static void main(String[] args) { try { File file = new File('F:\XMLFile.xml'); DocumentBuilder documentBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document document = documentBuilder.parse(file); System.out.println('Root element: '+ document.getDocumentElement().getNodeName()); if (document.hasChildNodes()) { printNodeList(document.getChildNodes()); } } catch (Exception e) { System.out.println(e.getMessage()); } } private static void printNodeList(NodeList nodeList) { for (int count = 0; count <nodelist.getlength(); count++) { node elemnode="nodeList.item(count);" if (elemnode.getnodetype()="=" node.element_node) get name and value system.out.println(' node [open]'); system.out.println('node content=" + elemNode.getTextContent()); if (elemNode.hasAttributes()) { NamedNodeMap nodeMap = elemNode.getAttributes(); for (int i = 0; i < nodeMap.getLength(); i++) { Node node = nodeMap.item(i); System.out.println(" attr : ' + node.getnodename()); system.out.println('attr node.getnodevalue()); } (elemnode.haschildnodes()) recursive call the has child nodes printnodelist(elemnode.getchildnodes()); [close]'); < pre> <p> <strong>Output:</strong> </p> <pre> Root element: class Node Name =class [OPEN] Node Content = 101 Naman Kumar Maths 83 102 Kapil Kumar Chemistry 60 103 Harsh Singh English 70 104 Jitesh Singh Physics 76 Node Name =student [OPEN] Node Content = 101 Naman Kumar Maths 83 Node Name =id [OPEN] Node Content =101 Node Name =id [CLOSE] Node Name =firstname [OPEN] Node Content =Naman Node Name =firstname [CLOSE] Node Name =lastname [OPEN] Node Content =Kumar Node Name =lastname [CLOSE] Node Name =subject [OPEN] Node Content =Math Node Name =subject [CLOSE] Node Name =marks [OPEN] Node Content =83 Node Name =marks [CLOSE] Node Name =student [CLOSE] Node Name =student [OPEN] Node Content = 102 Kapil Kumar Chemistry 60 Node Name =id [OPEN] Node Content =102 Node Name =id [CLOSE] Node Name =firstname [OPEN] Node Content =Kapil Node Name =firstname [CLOSE] Node Name =lastname [OPEN] Node Content =Kumar Node Name =lastname [CLOSE] Node Name =subject [OPEN] Node Content =Chemistry Node Name =subject [CLOSE] Node Name =marks [OPEN] Node Content =60 Node Name =marks [CLOSE] Node Name =student [CLOSE] Node Name =student [OPEN] Node Content = 103 Harsh Singh English 70 Node Name =id [OPEN] Node Content =103 Node Name =id [CLOSE] Node Name =firstname [OPEN] Node Content =Harsh Node Name =firstname [CLOSE] Node Name =lastname [OPEN] Node Content =Singh Node Name =lastname [CLOSE] Node Name =subject [OPEN] Node Content =English Node Name =subject [CLOSE] Node Name =marks [OPEN] Node Content =70 Node Name =marks [CLOSE] Node Name =student [CLOSE] Node Name =student [OPEN] Node Content = 104 Jitesh Singh Physics 76 Node Name =id [OPEN] Node Content =104 Node Name =id [CLOSE] Node Name =firstname [OPEN] Node Content =Jitesh Node Name =firstname [CLOSE] Node Name =lastname [OPEN] Node Content =Singh Node Name =lastname [CLOSE] Node Name =subject [OPEN] Node Content =Physics Node Name =subject [CLOSE] Node Name =marks [OPEN] Node Content =76 Node Name =marks [CLOSE] Node Name =student [CLOSE] Node Name =class [CLOSE] </pre> <h2>Java SAX Parser</h2> <p>Java SAX parser stands for <strong>Simple API</strong> for <strong>XML</strong> . SAX parser parses an XML file <strong>line by line</strong> . It triggers events when it encounters the opening tag, closing tag, and character data in an xml file. SAX parser is also called the <strong>event-based parser</strong> .</p> <p>SAX parser does not load any XML file into memory. It does not create any object representation of the XML document. SAX parser uses call back function to inform clients of the XML document structure. It is <strong>faster</strong> and uses <strong>less memory</strong> than DOM parser.</p> <p>SAX is a <strong>streaming interface</strong> for XML, which means that XML file parses in sequential order starting at the top of the document, and ending with the closing of the root element.</p> <p> <strong>Example of reading XML file using SAX parser</strong> </p> <pre> 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; public class ReadXMLFileExample3 { public static void main(String args[]) { try { SAXParserFactory factory = SAXParserFactory.newInstance(); SAXParser saxParser = factory.newSAXParser(); DefaultHandler handler = new DefaultHandler() { boolean id = false; boolean firstname = false; boolean lastname = false; boolean subject = false; boolean marks = false; //parser starts parsing a specific element inside the document public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { System.out.println('Start Element :' + qName); if(qName.equalsIgnoreCase('Id')) { id=true; } if (qName.equalsIgnoreCase('FIRSTNAME')) { firstname = true; } if (qName.equalsIgnoreCase('LASTNAME')) { lastname = true; } if (qName.equalsIgnoreCase('SUBJECT')) { subject = true; } if (qName.equalsIgnoreCase('MARKS')) { marks = true; } } //parser ends parsing the specific element inside the document public void endElement(String uri, String localName, String qName) throws SAXException { System.out.println('End Element:' + qName); } //reads the text value of the currently parsed element public void characters(char ch[], int start, int length) throws SAXException { if (id) { System.out.println('ID : ' + new String(ch, start, length)); id = false; } if (firstname) { System.out.println('First Name: ' + new String(ch, start, length)); firstname = false; } if (lastname) { System.out.println('Last Name: ' + new String(ch, start, length)); lastname = false; } if (subject) { System.out.println('Subject: ' + new String(ch, start, length)); subject = false; } if (marks) { System.out.println('Marks : ' + new String(ch, start, length)); marks = false; } } }; saxParser.parse('F:\XMLFile.xml', handler); } catch (Exception e) { e.printStackTrace(); } } } </pre> <p> <strong>Output:</strong> </p> <pre> Start Element: class Start Element: student Start Element: id ID: 101 End Element: id Start Element: firstname First Name: Naman End Element: firstname Start Element: lastname Last Name: Kumar End Element: lastname Start Element: subject Subject: Math End Element: subject Start Element: marks Marks: 83 End Element: marks End Element: student Start Element: student Start Element: id ID: 102 End Element: id Start Element: firstname First Name: Kapil End Element: firstname Start Element: lastname Last Name: Kumar End Element: lastname Start Element: subject Subject: Chemistry End Element: subject Start Element: marks Marks: 60 End Element: marks End Element: student Start Element: student Start Element: id ID: 103 End Element: id Start Element: firstname First Name: Harsh End Element: firstname Start Element: lastname Last Name: Singh End Element: lastname Start Element: subject Subject: English End Element: subject Start Element: marks Marks: 70 End Element: marks End Element: student Start Element: student Start Element: id ID: 104 End Element: id Start Element: firstname First Name: Jitesh End Element: firstname Start Element: lastname Last Name: Singh End Element: lastname Start Element: subject Subject: Physics End Element: subject Start Element: marks Marks: 76 End Element: marks End Element: student End Element: class </pre> <hr></nodelist.getlength();></pre></nodelist.getlength();>
Voyons un autre exemple de lecture de fichier XML.
Exemple de lecture d'un fichier XML à l'aide de DOM Parser
L'exemple suivant lit le même fichier XML FichierXML.xml , et montrant comment boucler les nœuds un par un. Il imprime la valeur du nœud, le nom et l'attribut le cas échéant.
Exemple
import java.io.File; import javax.xml.parsers.DocumentBuilder; import javax.xml.parsers.DocumentBuilderFactory; import org.w3c.dom.Document; import org.w3c.dom.NamedNodeMap; import org.w3c.dom.Node; import org.w3c.dom.NodeList; public class ReadXMLFileExample2 { public static void main(String[] args) { try { File file = new File('F:\XMLFile.xml'); DocumentBuilder documentBuilder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document document = documentBuilder.parse(file); System.out.println('Root element: '+ document.getDocumentElement().getNodeName()); if (document.hasChildNodes()) { printNodeList(document.getChildNodes()); } } catch (Exception e) { System.out.println(e.getMessage()); } } private static void printNodeList(NodeList nodeList) { for (int count = 0; count <nodelist.getlength(); count++) { node elemnode="nodeList.item(count);" if (elemnode.getnodetype()="=" node.element_node) get name and value system.out.println(\' node [open]\'); system.out.println(\'node content=" + elemNode.getTextContent()); if (elemNode.hasAttributes()) { NamedNodeMap nodeMap = elemNode.getAttributes(); for (int i = 0; i < nodeMap.getLength(); i++) { Node node = nodeMap.item(i); System.out.println(" attr : \' + node.getnodename()); system.out.println(\'attr node.getnodevalue()); } (elemnode.haschildnodes()) recursive call the has child nodes printnodelist(elemnode.getchildnodes()); [close]\'); < pre> <p> <strong>Output:</strong> </p> <pre> Root element: class Node Name =class [OPEN] Node Content = 101 Naman Kumar Maths 83 102 Kapil Kumar Chemistry 60 103 Harsh Singh English 70 104 Jitesh Singh Physics 76 Node Name =student [OPEN] Node Content = 101 Naman Kumar Maths 83 Node Name =id [OPEN] Node Content =101 Node Name =id [CLOSE] Node Name =firstname [OPEN] Node Content =Naman Node Name =firstname [CLOSE] Node Name =lastname [OPEN] Node Content =Kumar Node Name =lastname [CLOSE] Node Name =subject [OPEN] Node Content =Math Node Name =subject [CLOSE] Node Name =marks [OPEN] Node Content =83 Node Name =marks [CLOSE] Node Name =student [CLOSE] Node Name =student [OPEN] Node Content = 102 Kapil Kumar Chemistry 60 Node Name =id [OPEN] Node Content =102 Node Name =id [CLOSE] Node Name =firstname [OPEN] Node Content =Kapil Node Name =firstname [CLOSE] Node Name =lastname [OPEN] Node Content =Kumar Node Name =lastname [CLOSE] Node Name =subject [OPEN] Node Content =Chemistry Node Name =subject [CLOSE] Node Name =marks [OPEN] Node Content =60 Node Name =marks [CLOSE] Node Name =student [CLOSE] Node Name =student [OPEN] Node Content = 103 Harsh Singh English 70 Node Name =id [OPEN] Node Content =103 Node Name =id [CLOSE] Node Name =firstname [OPEN] Node Content =Harsh Node Name =firstname [CLOSE] Node Name =lastname [OPEN] Node Content =Singh Node Name =lastname [CLOSE] Node Name =subject [OPEN] Node Content =English Node Name =subject [CLOSE] Node Name =marks [OPEN] Node Content =70 Node Name =marks [CLOSE] Node Name =student [CLOSE] Node Name =student [OPEN] Node Content = 104 Jitesh Singh Physics 76 Node Name =id [OPEN] Node Content =104 Node Name =id [CLOSE] Node Name =firstname [OPEN] Node Content =Jitesh Node Name =firstname [CLOSE] Node Name =lastname [OPEN] Node Content =Singh Node Name =lastname [CLOSE] Node Name =subject [OPEN] Node Content =Physics Node Name =subject [CLOSE] Node Name =marks [OPEN] Node Content =76 Node Name =marks [CLOSE] Node Name =student [CLOSE] Node Name =class [CLOSE] </pre> <h2>Java SAX Parser</h2> <p>Java SAX parser stands for <strong>Simple API</strong> for <strong>XML</strong> . SAX parser parses an XML file <strong>line by line</strong> . It triggers events when it encounters the opening tag, closing tag, and character data in an xml file. SAX parser is also called the <strong>event-based parser</strong> .</p> <p>SAX parser does not load any XML file into memory. It does not create any object representation of the XML document. SAX parser uses call back function to inform clients of the XML document structure. It is <strong>faster</strong> and uses <strong>less memory</strong> than DOM parser.</p> <p>SAX is a <strong>streaming interface</strong> for XML, which means that XML file parses in sequential order starting at the top of the document, and ending with the closing of the root element.</p> <p> <strong>Example of reading XML file using SAX parser</strong> </p> <pre> 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; public class ReadXMLFileExample3 { public static void main(String args[]) { try { SAXParserFactory factory = SAXParserFactory.newInstance(); SAXParser saxParser = factory.newSAXParser(); DefaultHandler handler = new DefaultHandler() { boolean id = false; boolean firstname = false; boolean lastname = false; boolean subject = false; boolean marks = false; //parser starts parsing a specific element inside the document public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { System.out.println('Start Element :' + qName); if(qName.equalsIgnoreCase('Id')) { id=true; } if (qName.equalsIgnoreCase('FIRSTNAME')) { firstname = true; } if (qName.equalsIgnoreCase('LASTNAME')) { lastname = true; } if (qName.equalsIgnoreCase('SUBJECT')) { subject = true; } if (qName.equalsIgnoreCase('MARKS')) { marks = true; } } //parser ends parsing the specific element inside the document public void endElement(String uri, String localName, String qName) throws SAXException { System.out.println('End Element:' + qName); } //reads the text value of the currently parsed element public void characters(char ch[], int start, int length) throws SAXException { if (id) { System.out.println('ID : ' + new String(ch, start, length)); id = false; } if (firstname) { System.out.println('First Name: ' + new String(ch, start, length)); firstname = false; } if (lastname) { System.out.println('Last Name: ' + new String(ch, start, length)); lastname = false; } if (subject) { System.out.println('Subject: ' + new String(ch, start, length)); subject = false; } if (marks) { System.out.println('Marks : ' + new String(ch, start, length)); marks = false; } } }; saxParser.parse('F:\XMLFile.xml', handler); } catch (Exception e) { e.printStackTrace(); } } } </pre> <p> <strong>Output:</strong> </p> <pre> Start Element: class Start Element: student Start Element: id ID: 101 End Element: id Start Element: firstname First Name: Naman End Element: firstname Start Element: lastname Last Name: Kumar End Element: lastname Start Element: subject Subject: Math End Element: subject Start Element: marks Marks: 83 End Element: marks End Element: student Start Element: student Start Element: id ID: 102 End Element: id Start Element: firstname First Name: Kapil End Element: firstname Start Element: lastname Last Name: Kumar End Element: lastname Start Element: subject Subject: Chemistry End Element: subject Start Element: marks Marks: 60 End Element: marks End Element: student Start Element: student Start Element: id ID: 103 End Element: id Start Element: firstname First Name: Harsh End Element: firstname Start Element: lastname Last Name: Singh End Element: lastname Start Element: subject Subject: English End Element: subject Start Element: marks Marks: 70 End Element: marks End Element: student Start Element: student Start Element: id ID: 104 End Element: id Start Element: firstname First Name: Jitesh End Element: firstname Start Element: lastname Last Name: Singh End Element: lastname Start Element: subject Subject: Physics End Element: subject Start Element: marks Marks: 76 End Element: marks End Element: student End Element: class </pre> <hr></nodelist.getlength();>
Analyseur Java SAX
L'analyseur Java SAX signifie API simple pour XML . L'analyseur SAX analyse un fichier XML ligne par ligne . Il déclenche des événements lorsqu'il rencontre la balise d'ouverture, la balise de fermeture et les données de caractères dans un fichier XML. L'analyseur SAX est également appelé le analyseur basé sur les événements .
L'analyseur SAX ne charge aucun fichier XML en mémoire. Il ne crée aucune représentation objet du document XML. L'analyseur SAX utilise la fonction de rappel pour informer les clients de la structure du document XML. C'est plus rapide et utilise moins de mémoire que l'analyseur DOM.
SAX est un interface de diffusion en continu pour XML, ce qui signifie que le fichier XML est analysé dans un ordre séquentiel en commençant par le haut du document et en se terminant par la fermeture de l'élément racine.
programmation int c non signée
Exemple de lecture d'un fichier XML à l'aide de l'analyseur SAX
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; public class ReadXMLFileExample3 { public static void main(String args[]) { try { SAXParserFactory factory = SAXParserFactory.newInstance(); SAXParser saxParser = factory.newSAXParser(); DefaultHandler handler = new DefaultHandler() { boolean id = false; boolean firstname = false; boolean lastname = false; boolean subject = false; boolean marks = false; //parser starts parsing a specific element inside the document public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { System.out.println('Start Element :' + qName); if(qName.equalsIgnoreCase('Id')) { id=true; } if (qName.equalsIgnoreCase('FIRSTNAME')) { firstname = true; } if (qName.equalsIgnoreCase('LASTNAME')) { lastname = true; } if (qName.equalsIgnoreCase('SUBJECT')) { subject = true; } if (qName.equalsIgnoreCase('MARKS')) { marks = true; } } //parser ends parsing the specific element inside the document public void endElement(String uri, String localName, String qName) throws SAXException { System.out.println('End Element:' + qName); } //reads the text value of the currently parsed element public void characters(char ch[], int start, int length) throws SAXException { if (id) { System.out.println('ID : ' + new String(ch, start, length)); id = false; } if (firstname) { System.out.println('First Name: ' + new String(ch, start, length)); firstname = false; } if (lastname) { System.out.println('Last Name: ' + new String(ch, start, length)); lastname = false; } if (subject) { System.out.println('Subject: ' + new String(ch, start, length)); subject = false; } if (marks) { System.out.println('Marks : ' + new String(ch, start, length)); marks = false; } } }; saxParser.parse('F:\XMLFile.xml', handler); } catch (Exception e) { e.printStackTrace(); } } }
Sortir:
Start Element: class Start Element: student Start Element: id ID: 101 End Element: id Start Element: firstname First Name: Naman End Element: firstname Start Element: lastname Last Name: Kumar End Element: lastname Start Element: subject Subject: Math End Element: subject Start Element: marks Marks: 83 End Element: marks End Element: student Start Element: student Start Element: id ID: 102 End Element: id Start Element: firstname First Name: Kapil End Element: firstname Start Element: lastname Last Name: Kumar End Element: lastname Start Element: subject Subject: Chemistry End Element: subject Start Element: marks Marks: 60 End Element: marks End Element: student Start Element: student Start Element: id ID: 103 End Element: id Start Element: firstname First Name: Harsh End Element: firstname Start Element: lastname Last Name: Singh End Element: lastname Start Element: subject Subject: English End Element: subject Start Element: marks Marks: 70 End Element: marks End Element: student Start Element: student Start Element: id ID: 104 End Element: id Start Element: firstname First Name: Jitesh End Element: firstname Start Element: lastname Last Name: Singh End Element: lastname Start Element: subject Subject: Physics End Element: subject Start Element: marks Marks: 76 End Element: marks End Element: student End Element: class