With this example we are going to demonstrate how to remove a Node from a DOM Document. We have implemented a method, that is void prettyPrint(Document xml), in order to convert a DOM into a formatted XML String. In short, to remove a Node from a DOM Document you should:
- Obtain a new instance of a DocumentBuilderFactory, that is a factory API that enables applications to obtain a parser that produces DOM object trees from XML documents.
- Set the parser produced so as not to validate documents as they are parsed, using
setValidating(boolean validating)API method of DocumentBuilderFactory, with validating set to false. - Create a new instance of a DocumentBuilder, using
newDocumentBuilder()API method of DocumentBuilderFactory. - Parse the FileInputStream with the content to be parsed, using
parse(InputStream is)API method of DocumentBuilder. This method parses the content of the given InputStream as an XML document and returns a new DOM Document object. - Get the NodeList of all the Elements in document order with a given tag name, using
getElementsByTagName(String tagname)API method of Document, and from this nodeList get the first element. - Remove this element from the DOM Document. Get the parent node of this element, using
getParentNode()API method of Node, and remove the specified child, usingremoveChild(Node oldChild)API method of Node. - Use
normalize()API method of Document, to normalize the DOM tree. The method puts all text nodes in the full depth of the sub-tree underneath this node. - Call
void prettyPrint(Document xml)method of the example. The method gets the xml Document and converts it into a formatted xml String, after transforming it with specific parameters, such as encoding. The method uses a Transformer, that is created usingnewTransformer()API method of TransformerFactory. The Transformer is used to transform a source tree into a result tree. After setting specific output properties to the transformer, usingsetOutputProperty(String name, String value)API method of Transformer, the method uses it to make the transformation, withtransform(Source xmlSource, Result outputTarget)API method of Transformer. The parameters are the DOMSource with the DOM node and the result that is a StreamResult created from a StringWriter.
Let’s take a look at the code snippet that follows:
package com.javacodegeeks.snippets.core;
import java.io.File;
import java.io.FileInputStream;
import java.io.StringWriter;
import java.io.Writer;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.OutputKeys;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
public class RemoveNodeFromDOMDocument {
public static void main(String[] args) throws Exception {
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setValidating(false);
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(new FileInputStream(new File("in.xml")));
// retrieve the element 'link'
Element element = (Element) doc.getElementsByTagName("link").item(0);
// remove the specific node
element.getParentNode().removeChild(element);
// Normalize the DOM tree, puts all text nodes in the
// full depth of the sub-tree underneath this node
doc.normalize();
prettyPrint(doc);
}
public static final void prettyPrint(Document xml) throws Exception {
Transformer tf = TransformerFactory.newInstance().newTransformer();
tf.setOutputProperty(OutputKeys.ENCODING, "UTF-8");
tf.setOutputProperty(OutputKeys.INDENT, "yes");
Writer out = new StringWriter();
tf.transform(new DOMSource(xml), new StreamResult(out));
System.out.println(out.toString());
}
}
Input:
<?xml version="1.0" encoding="UTF-8"?> <rss version="2.0"> <channel> <title>Java Tutorials and Examples</title> <item> <title><![CDATA[Java Tutorials]]></title> <link>http://www.javacodegeeks.com/</link> </item> </channel> </rss>
Output:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<rss version="2.0">
<channel>
<title>Java Tutorials and Examples</title>
<item>
<title><![CDATA[Java Tutorials]]></title>
</item>
</channel>
</rss>
This was an example of how to remove a Node from a DOM Document in Java.
