pf » Parsing, Modifying, and outputting XML Documents with Java
Parsing, Modifying, and outputting XML Documents with Java
I have been doing a lot of XML parsing, and manipulation in java lately because I'm building a super dynamic configuration editor for XMS. Its going to be pretty cool once its done because you can even configure third party modules with it. Anyways I thought I'd post some a simple example of parsing and modifying XML with java:
Suppose you have the following XML document:
<?xml version="1.0" ?>
<earth>
<country>us</country>
</earth>
First to parse it using a DOM parser, you can use the DocumentBuilderFactory to get the default DOM parser for your JVM:
DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
Document doc = docBuilder.parse("/path/to/file.xml");
Now you have an object representation of the XML file in a DOM Document object.
Adding an attribute
Suppose you wanted to add an attribute to the earth node:
Node earth = doc.getFirstChild();
NamedNodeMap earthAttributes = earth.getAttributes();
Attr galaxy = doc.createAttribute("galaxy");
galaxy.setValue("milky way");
earthAttributes.setNamedItem(galaxy);
Adding a child tag
Now lets suppose you wanted to add a child node:
Node canada = doc.createElement("country");
canada.setTextContent("ca");
earth.appendChild(canada);
Write the XML document to a string or file
Finally you probably want to write the xml document to a string or to a file, this can be done with a Transformer object, which come from the transformer factory:
Transformer transformer = TransformerFactory.newInstance().newTransformer(); transformer.setOutputProperty(OutputKeys.INDENT, "yes"); //initialize StreamResult with File object to save to file StreamResult result = new StreamResult(new StringWriter()); DOMSource source = new DOMSource(doc); transformer.transform(source, result); String xmlString = result.getWriter().toString(); System.out.println(xmlString);
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//initialize StreamResult with File object to save to file StreamResult result = new StreamResult(new StringWriter()); DOMSource source = new DOMSource(doc); trans.transform(source, result);
String xmlString = result.getWriter().toString(); System.out.println(xmlString);
Hi i dont understand what is trans in trans.transform(source, result);
Ah, forgot to mention that I'm a newbie and this is my first coding experiment with Java, so excuse me if the question sounds silly.
Thanks.
Is there way to modify XML file using JAXP, I am able to overwrite the file with the changes need, but would like to have the same file modified(one particular tag) than completely overwriting the XML file.
Thanks , Vijay
Thanks Kishore
When you set the indent output property of a transformer to true, and write the xml file, it inserts text nodes to facilitate the new-lines and tabs. Then when you parse, it reads these new-lines and tabs as text nodes. Then if i remove a node that is between two other nodes, and re-write the xml file, the surrounding text nodes are concatenated and we see a big break.
Thusly:
Original xml:
<HeadTag> <Stuff>"First"</Stuff> <Stuff>"Second"</Stuff> <Stuff>"Third"</Stuff> </HeadTag>
then if I parse and remove the Element with name "Stuff" and text content "Second" and then re-write, I see:
<HeadTag> <Stuff>"First"</Stuff> <Stuff>"Third"</Stuff> </HeadTag>
I have confirmed this is what is happening by obtaining a NodeList of all the children of the documentElement and traversing the list printing the node type name and value for each.
Any suggestions?
~Jason
Original:
<HeadTag><p> <br><br><Stuff>"First"</Stuff><p> <br><br><Stuff>"Second"</Stuff><p> <br><br><Stuff>"Third"</Stuff><p> </HeadTag>
After deleting 'Stuff' element with "Second": <HeadTag><p> <br><br><Stuff>"First"</Stuff><p> <p> <br><br><Stuff>"Third"</Stuff><p> </HeadTag>
Right then if any updates plz send it to my Email id muqthadir_ali@yahoo.co.in
<element name="os"> <type>linux</type> <version>4.0</version> </element> </element>
How do i remove the Element with the name "element" and replace it with the attribute value.
Help me in this regards....
How do i remove the Element with the name "element" and replace it with the attribute value.
if you have a small example for this ...please provide me
regards tirumala
Does this code handles reading very large XML files.. say around 1 GB in size? How to read those files? Thanks
I also get [#document : null] when using DocumentBuilderFactory... does anyone have a reason/solution for this?
please let me know..
here is the pgm:
import org.w3c.dom.*; import org.apache.xerces.parsers.DOMParser; import java.io.*; //import javax.xml.parsers.DocumentBuilder; //import javax.xml.parsers.DocumentBuilderFactory;
public class CountNodes { public static void main(String[] args) { try{ BufferedReader bf = new BufferedReader(new InputStreamReader(System.in)); System.out.print("Enter file name: "); String str = bf.readLine(); File file = new File(str); if (file.exists()){ DOMParser parser = new DOMParser(); parser.parse(str); Document doc = parser.getDocument(); /* DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder = factory.newDocumentBuilder(); Document doc = builder.parse(file);*/ System.out.print("Enter element that have to count: "); String ele = bf.readLine(); NodeList list = doc.getElementsByTagName(ele); System.out.println("Number of nodes: " + list.getLength()); } else{ System.out.println("File not found!"); } } catch (Exception e){ e.getMessage(); } } }
here is the pgm:
import org.w3c.dom.*; import org.apache.xerces.parsers.DOMParser; import java.io.*; //import javax.xml.parsers.DocumentBuilder; //import javax.xml.parsers.DocumentBuilderFactory;
public class CountNodes { public static void main(String[] args) { try{ BufferedReader bf = new BufferedReader(new InputStreamReader(System.in)); System.out.print("Enter file name: "); String str = bf.readLine(); File file = new File(str); if (file.exists()){ DOMParser parser = new DOMParser(); parser.parse(str); Document doc = parser.getDocument(); /* DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); DocumentBuilder builder = factory.newDocumentBuilder(); Document doc = builder.parse(file);*/ System.out.print("Enter element that have to count: "); String ele = bf.readLine(); NodeList list = doc.getElementsByTagName(ele); System.out.println("Number of nodes: " + list.getLength()); } else{ System.out.println("File not found!"); } } catch (Exception e){ e.getMessage(); } } }
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Pete Freitag is a software engineer, and web developer located in central new york.
Pete's company Foundeo Inc. builds products for web developers and provides consulting services.
In 2003 Pete published the ColdFusion MX Developers Cookbook with SAMs Publishing.
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