xml and java

Replies

• 

  viswasknit

  here i want give detail of my problem...
  
  
  A xml file book.xml
  
  
  
  
  
  roy
  
  
  
  herbert
  
  
  
  robert
  
  
  
  allaire
  
  
  
  morrison
  
  
  
  allaire
  
  
  
  Now i want a jsp page to take data of book.xml file..............
  
  
  I use tomcat 6.018 as a server...............
• 

  sookie

  JSP Part, I am leaving to you, if get stuck anywhere, feel free to ask. Below is how to read .xml file in Java file.
  
  Pre-requisite: Knowledge of Parsers -SAX and DOM.
  
  Taking your Books.xml example only
  Books.xml
  

  
  
  
  
  
  roy
  
  
  
  
  herbert
  
  
  
  
  robert
  
  
  
  
  allaire
  
  
  
  
  morrison
  
  
  
  

  Now how to retrieve this data in Java program. There are two approaches of doing so:
  1. Using SAX [Simple API for XML]
  
  

  package myjava;
  
  import java.io.File;
  import java.io.IOException;
  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 XMLReaderUsingSAX {
  
      public static void main(String[] args) throws IOException {
          String xmlFile = "I:/Books.xml";
          System.out.print("XML file name:" + xmlFile);
          XMLReaderUsingSAX detail = new XMLReaderUsingSAX(xmlFile);
      }
  
      public XMLReaderUsingSAX(String str) {
          try {
              File file = new File(str);
              /*checks if the file exists */
              if (file.exists()) {
                  SAXParserFactory parserFact = SAXParserFactory.newInstance();
                  SAXParser parser = parserFact.newSAXParser();
                  System.out.println("XML Data: ");
                  DefaultHandler dHandler = new DefaultHandler() {
  
                      boolean title;
                      boolean author;
                      boolean mail;
  
                      public void startElement(String uri, String localName, String element_name, Attributes attributes) throws SAXException {
                          if (element_name.equals("title")) {
                              title = true;
                          }
                          if (element_name.equals("author")) {
                              author = true;
                          }
                      }
  
                      public void characters(char[] ch, int start, int len) throws SAXException {
                          String str = new String(ch, start, len);
                          if (title) {
                              System.out.println("Title:" + str);
                              title = false;
                          }
                          if (author) {
                              System.out.println("Author:" + str);
                              author = false;
                          }
                      }
                  };
  
                  parser.parse(str, dHandler);
              } else {
                  System.out.println("File not found!");
              }
          } catch (Exception e) {
              System.out.println("XML File hasn't any elements");
              e.printStackTrace();
          }
      }
  }
  

  Output:
  

  XML file name:I:/Books.xmlXML Data:
  Title:cobol
  Author:roy
  Title:java
  Author:herbert
  Title:c++
  Author:robert
  Title:coldfusion
  Author:allaire
  Title:xml unleashed
  Author:morrison

  In above Java class, SAXParser class parses the XML file using parse() method. The characters() method prints data until value of element in startElement() is true
  
  Characters(char[] ch, int start, int len) method retrieves identification of character data. The Parser calls this method and to report every character data encountered . If any error occurs it throws the SAXException. This method takes the following parameters:
  
  

  • ch: This is the characters of XML document.
  • start: This is staring position in an array.
  • len: This is the number of characters to read from an array.

  
  2. Using DOM[Document Object Model]
  

  package myjava;
  
  import java.io.File;
  import javax.xml.parsers.DocumentBuilder;
  import javax.xml.parsers.DocumentBuilderFactory;
  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  import org.w3c.dom.Node;
  import org.w3c.dom.NodeList;
  
  public class XMLReaderUsingDOM {
  
      public static void main(String argv[]) {
  
          try {
              File file = new File("I:/Books.xml");
              DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
              DocumentBuilder db = dbf.newDocumentBuilder();
              Document doc = (Document) db.parse(file);
              doc.getDocumentElement().normalize();
              NodeList nodeList = doc.getElementsByTagName("book");
  
  
              for (int s = 0; s < nodeList.getLength(); s++) {
  
                  Node firstNode = nodeList.item(s);
  
                  if (firstNode.getNodeType() == Node.ELEMENT_NODE) {
  
                      Element firstElement = (Element) firstNode;
                      NodeList fstNmElmntLst = firstElement.getElementsByTagName("title");
                      Element fstNmElmnt = (Element) fstNmElmntLst.item(0);
                      NodeList fstNm = fstNmElmnt.getChildNodes();
                      System.out.println("Title: " + ((Node) fstNm.item(0)).getNodeValue());
                      NodeList lstNmElmntLst = firstElement.getElementsByTagName("author");
                      Element lstNmElmnt = (Element) lstNmElmntLst.item(0);
                      NodeList lstNm = lstNmElmnt.getChildNodes();
                      System.out.println("Author: " + ((Node) lstNm.item(0)).getNodeValue());
                  }
  
              }
          } catch (Exception e) {
              e.printStackTrace();
          }
      }
  }
  

  Output:
  

  Title: cobol
  Author: roy
  Title: java
  Author: herbert
  Title: c++
  Author: robert
  Title: coldfusion
  Author: allaire
  Title: xml unleashed
  Author: morrison

  In case 2, "book" is kind of hard-coded.
  
  For more information about SAX and DOM, check following
  #-Link-Snipped-#
  #-Link-Snipped-#
  
  Let me know, if you need any more details. Thanks !