Develop Reference

Java - Delete child node from dynamic XML

I want to delete a XML node that contains a PDF in Base64. This is an example:
<?xml version="1.0" encoding="UTF-8"?>
<getResult>
<id>null</id>
<pdf>ioje98fh23fjkiwf72322342</pdf>
</getResult>
First, I transform the XML in String to Document but the result is null. This is my code:
DocumentBuilder dbf = null;
Document doc = null;
try {
dbf = DocumentBuilderFactory.newInstance().newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(new StringReader("<getResult><id>null</id><pdf>ioje98fh23fjkiwf72322342</pdf></getResult>"));
doc = dbf.parse(is);
NodeList children = doc. getChildNodes();
for (int i = 0; i < children.getLength(); i++) {
Node currentChild = children.item(i);
System.out.println(currentChild);
}
} catch (Exception e) {
System.out.println(e.getMessage().toString());
}
The result is always: [getResult: null]
Considering that the main node can vary but the structure does not, How can I get the PDF node?

Here is the could you could use to retrieve the data.
import java.io.StringReader;
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;
import org.xml.sax.InputSource;
import org.w3c.dom.CharacterData;
public class LabFour {
public static void main(String[] args) {
DocumentBuilder dbf = null;
Document doc = null;
try {
dbf = DocumentBuilderFactory.newInstance().newDocumentBuilder();
InputSource is = new InputSource();
is.setCharacterStream(
new StringReader("<getResult><id>null</id><pdf>ioje98fh23fjkiwf72322342</pdf></getResult>"));
doc = dbf.parse(is);
NodeList nodes = doc.getElementsByTagName("getResult");
for (int i = 0; i < nodes.getLength(); i++) {
Element element = (Element) nodes.item(i);
NodeList name = element.getElementsByTagName("id");
Element line = (Element) name.item(0);
System.out.println("id: " + getCharacterDataFromElement(line));
NodeList pdf = element.getElementsByTagName("pdf");
line = (Element) title.item(0);
System.out.println("pdf: " + getCharacterDataFromElement(pdf));
}
} catch (Exception e) {
e.printStackTrace();
}
}
public static String getCharacterDataFromElement(Element e) {
Node child = e.getFirstChild();
if (child instanceof CharacterData) {
CharacterData cd = (CharacterData) child;
return cd.getData();
}
return "?";
}
}

SimpleXml can do it:
final SimpleXml simple = new SimpleXml();
final Element element = simple.fromXml(data);
element.children.remove(1);
System.out.println(simple.domToXml(element));
Will output:
<getResult><id>null</id></getResult>
From maven central:
<dependency>
<groupId>com.github.codemonstur</groupId>
<artifactId>simplexml</artifactId>
<version>1.4.0</version>
</dependency>

Java: Function that parses XML data - nothing being outputted

I'm relatively new to XML processing with Java, so expect some mistakes, but anyway...I'm trying to parse the following XML data:
http://msdn.microsoft.com/en-us/library/ms762271(v=vs.85).aspx
I would like to accomplish this using a function, where the name of the XML tag and NodeList are passed in as parameters, and it returns the content.
Thanks.
import java.io.*;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Element;
import org.xml.sax.SAXException;
public class Files {
#SuppressWarnings("unused")
public static void main (String [] args) throws IOException, ParserConfigurationException, SAXException{
String address = "/home/leo/workspace/Test/Files/src/file.xml";
String author = "author";
String title = "title";
String genre = "genre";
String price = "price";
String publish = "publish_date";
String descr = "description";
File xmlFile = new File(address);
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = factory.newDocumentBuilder();
Document doc = dBuilder.parse(xmlFile);
doc.getDocumentElement().normalize();
System.out.println(doc.getDocumentElement().getNodeName());
NodeList n = doc.getElementsByTagName("book");
System.out.println("Number of books " + n.getLength());
getElement(author, n);
}
private static void getElement(String elementName, NodeList n){
for (int i = 0; i < n.getLength(); i++){
Node showNode = n.item(i);
Element showElement = (Element)showNode;
System.out.println(elementName + ": " +
showElement.getAttribute(elementName)
);
}
}
}

The problem is : showElement.getAttribute(elementName)
you want to get the value of a node,but getAttribute is to get the attribute of the node,you should figure out what attribute means in XML.
you can get the value like this:
private static void getElement(String elementName, NodeList n){
for (int i = 0; i < n.getLength(); i++){
Node showNode = n.item(i);
NodeList nl = showNode.getChildNodes();
for(int j=0;j<nl.getLength();j++)
{
Node nd=nl.item(j);
if(nd.getNodeName().equals(elementName))
{
System.out.println(elementName + ":" + nd.getTextContent());
}
}
}
}
}

Parsing XML attributes from Complex Empty Elements

I have an xml file in the following pattern which contains a few Complex Empty Elements(elements with no content, only attributes).
<items>
<item id="0" name="a" />
<item id="1" name="b" />
</items>
I'm at lose to parse the attributes from them. This is what I have done so far :
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(inputStream);
Element itemsElement = document.getDocumentElement();
if (itemsElement.getTagName().equals(TAG_ITEMS)) {
NodeList nodeList = itemsElement.getChildNodes();
for (int i = 0; i < nodeList.getLength(); i++) {
// process each item node
Node node = nodeList.item(i);
if (node.getNodeType() == Node.TEXT_NODE) { // Is this the right way?
Text text = (Text) node;
// Do stuff with attributes
}
}
}
I cannot cast these Text nodes to Element nodes and get attributes, I cannot get attributes from node using getAttributes - NPE at NamedNodeMap attributes.getLength(), I cannot cast it to Text and get attributes. How can I parse the attributes?

You are not interested in the text context of the nodes inside of items but in the attributes of the nodes item. you could proceed as follow:
//process each item node
Node node = nodeList.item(i);
if (node.getNodeName().equals("item")) {
NamedNodeMap attributes = node.getAttributes();
System.out.printf("id=%s, name=%s%n",
attributes.getNamedItem("id").getTextContent(),
attributes.getNamedItem("name").getTextContent());
}
This would print:
id=0, name=a
id=1, name=b

Assuming you want to get the indiviudal attributes of the nodes you need to one of two things (or both depending on your needs)...
You need to test if the current node is an ELEMENT_NODE or if the current node's name is equal to item (assuming all the node names are the same), for example...
import java.io.InputStream;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;
public class Test {
public static final String TAG_ITEMS = "items";
public static void main(String[] args) {
try (InputStream is = Test.class.getResourceAsStream("/Test.xml")) {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(is);
Element itemsElement = document.getDocumentElement();
if (itemsElement.getTagName().equals(TAG_ITEMS)) {
NodeList nodeList = itemsElement.getChildNodes();
for (int i = 0; i < nodeList.getLength(); i++) {
Node node = nodeList.item(i);
if (node.getNodeType() == Node.ELEMENT_NODE) {
NamedNodeMap attributes = node.getAttributes();
Node idAtt = attributes.getNamedItem("id");
Node nameAtt = attributes.getNamedItem("name");
System.out.println("id = " + idAtt.getNodeValue());
System.out.println("name = " + nameAtt.getNodeValue());
}
}
}
} catch (Exception exp) {
exp.printStackTrace();
}
}
}
Which will output...
id = 0
name = a
id = 1
name = b
All of this could be greatly reduced by using XPath, for example, if all the item nodes are the same name, then you could just use
/items/item
As the query. If the node names are different, but the attributes are the same, then you could use
/items/*[#id]
which will list all the nodes under items which has an id attribute, or
/items/*[#name]
which will list all the nodes under items which has an name attribute...
import java.io.InputStream;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Document;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
public class Test {
public static void main(String[] args) {
try (InputStream is = Test.class.getResourceAsStream("/Test.xml")) {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document document = builder.parse(is);
XPath xpath = XPathFactory.newInstance().newXPath();
XPathExpression expression = xpath.compile("/items/item");
NodeList nodes = (NodeList) expression.evaluate(document, XPathConstants.NODESET);
process(nodes);
expression = xpath.compile("/items/*[#id]");
nodes = (NodeList) expression.evaluate(document, XPathConstants.NODESET);
process(nodes);
expression = xpath.compile("/items/*[#name]");
nodes = (NodeList) expression.evaluate(document, XPathConstants.NODESET);
process(nodes);
} catch (Exception exp) {
exp.printStackTrace();
}
}
protected static void process(NodeList nodes) {
for (int index = 0; index < nodes.getLength(); index++) {
Node item = nodes.item(index);
NamedNodeMap attributes = item.getAttributes();
Node idAtt = attributes.getNamedItem("id");
Node nameAtt = attributes.getNamedItem("name");
System.out.println("id = " + idAtt.getNodeValue() + "; name = " + nameAtt.getNodeValue());
}
}
}

java xml parsing dblp

this is the xml file
please how to parse the tag author example we dont know how many author for each inproceeding ?
<?xml version="1.0" encoding="ISO-8859-1"?>
<dblp>
<inproceedings mdate="2014-01-18" key="series/sci/AzzagL13">
<author>Hanane Azzag</author>
<author>Mustapha Lebbah</author>
<title>A New Way for Hierarchical and Topological Clustering.</title>
<pages>85-97</pages>
<year>2011</year>
<booktitle>EGC (best of volume)</booktitle>
<ee>http://dx.doi.org/10.1007/978-3-642-35855-5_5</ee>
<crossref>series/sci/2013-471</crossref>
<url>db/series/sci/sci471.html#AzzagL13</url>
</inproceedings>
<inproceedings mdate="2014-01-18" key="series/sci/RabatelBP13">
<author>Julien Rabatel</author>
<author>Sandra Bringay</author>
<author>Pascal Poncelet</author>
<title>Mining Sequential Patterns: A Context-Aware Approach.</title>
<pages>23-41</pages>
<year>2011</year>
<booktitle>EGC (best of volume)</booktitle>
<ee>http://dx.doi.org/10.1007/978-3-642-35855-5_2</ee>
<crossref>series/sci/2013-471</crossref>
<url>db/series/sci/sci471.html#RabatelBP13</url>
</inproceedings>
</dblp>

Use Xpath, it's fast and powerfull , these lines for your example return 5 lines
Code:
final Document document = DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(new FileInputStream("input.xml"));
final XPath xPath = XPathFactory.newInstance().newXPath();
final NodeList nodeList = (NodeList) xPath.compile("//author").evaluate(document, XPathConstants.NODESET);
for (int i = 0; i < nodeList.getLength(); i++) {
System.out.println(nodeList.item(i).getFirstChild().getNodeValue());
}
Displays:
Hanane Azzag
Mustapha Lebbah
Julien Rabatel
Sandra Bringay
Pascal Poncelet

Following code parse using apache digester which is commonly used while parsing in real projects. Nice one from apache community
// Updated code as per you need.
import java.io.ByteArrayInputStream;
import java.io.FileInputStream;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import org.apache.commons.digester.Digester;
import org.apache.commons.digester.Rule;
import org.apache.commons.digester.Rules;
import org.xml.sax.InputSource;
public class Parsing {
public static void main(String[] args) throws Exception{
InputStream data = new FileInputStream("E:\\workspace\\trunk\\Parsing\\src\\data.xml");
byte[] b = new byte[data.available()];
// data.read(b);
Digester digester = new Digester();
//Genearting Array list while encountering dblp xpath
digester.addObjectCreate("dblp", HashMap.class);
digester.addObjectCreate("dblp/inproceedings", ArrayList.class);
//Calling add method while encountering author xpath
AuthorRule rule = new AuthorRule();
digester.addRule("dblp/inproceedings/author", rule);
digester.addRule("dblp/inproceedings/title", rule);
digester.addRule("dblp/inproceedings", rule);
HashMap parsedData = (HashMap) digester.parse(data);
Iterator<Entry<String, ArrayList>> dataItr = parsedData.entrySet().iterator();
while(dataItr.hasNext()){
Entry<String, ArrayList> entry = dataItr.next();
System.out.println("Title : " + entry.getKey() + ", Authors" + entry.getValue().toString());
}
}
private static class AuthorRule extends Rule{
String currentTitle = "";
#Override
public void body(String namespace, String name, String text)
throws Exception {
HashMap object = (HashMap) digester.peek(1);
ArrayList authors = (ArrayList) digester.peek(0);
if(name.equals("title")){
currentTitle = text;
}
else if(name.equals("author")){
authors.add(text);
}
}
#Override
public void end(String namespace, String name) throws Exception {
HashMap object = (HashMap) digester.peek(1);
ArrayList authors = (ArrayList) digester.peek(0);
if(name.equals("inproceedings")){
object.put(currentTitle, authors);
}
}
}
}
output::
Title : A New Way for Hierarchical and Topological Clustering., Authros[Hanane Azzag, Mustapha Lebbah]
Title : Mining Sequential Patterns: A Context-Aware Approach., Authros[Julien Rabatel, Sandra Bringay, Pascal Poncelet]

there are number of ways, e.g. via DOM:
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import java.io.File;
public class XmlAuthorReader {
public static void main(String argv[]) {
try {
File fXmlFile = new File(<filePath>);
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(fXmlFile);
NodeList nList = doc.getElementsByTagName("author");
System.out.println(nList.getLength()+ " author(s) found");
for (int temp = 0; temp < nList.getLength(); temp++) {
Node nNode = nList.item(temp);
System.out.println("Author: " + nNode.getTextContent());
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
you can find more variants here: http://www.mkyong.com/tutorials/java-xml-tutorials/

Why is this java code not parsing my Xml correctly?

I've written class to parse some xml into an object and it's not working correctly, when I try and get the value of a node I get a null rather than the contents of the node.
Here is a simplified version of my class that just does the xml parsing of a single node:
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.apache.log4j.Logger;
import org.apache.log4j.xml.DOMConfigurator;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;
public class XmlReaderCutDown {
private static Logger logger = Logger.getLogger(CtiButtonsXmlReader.class);
public static void testXml(String confFile){
DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
Document doc = docBuilder.parse(new File(confFile));
doc.getDocumentElement().normalize();
if (logger.isDebugEnabled()){
logger.debug("The root element is " + doc.getDocumentElement().getNodeName());
}
NodeList rows = doc.getElementsByTagName("row");
NodeList topRowButtons = ((Element)rows.item(0)).getElementsByTagName("button");
logger.debug("Top row has " +topRowButtons.getLength() + " items.");
Node buttonNode = topRowButtons.item(0);
NodeList nodeList = ((Element)buttonNode).getElementsByTagName("id");
logger.debug("Node list count for "+ "id" + " = " + nodeList.getLength());
Element element = (Element)nodeList.item(0);
String xx = element.getNodeValue();
logger.debug(xx);
String elementValue = ((Node)element).getNodeValue();
if (elementValue != null) {
elementValue = elementValue.trim();
}
else {
logger.debug("Value was null");
}
logger.debug("Node id = "+ elementValue);
} catch (ParserConfigurationException e) {
logger.fatal(e.toString(),e);
} catch (SAXException e) {
logger.fatal(e.toString(),e);
} catch (IOException e) {
logger.fatal(e.toString(),e);
} catch (Exception e) {
logger.fatal(e.toString(),e);
}
}
public static void main(String[] args){
DOMConfigurator.configure("log4j.xml");
testXml("test.xml");
}
}
And here is a stripped down version of my xml file:
<?xml version="1.0"?>
<root>
<row>
<button>
<id>this is an id</id>
<action>action</action>
<image-src>../images/img.png</image-src>
<alt-text>alt txt</alt-text>
<tool-tip>Tool tip</tool-tip>
</button>
</row>
</root>
This is what the logging statments output:
DEBUG XmlReaderCutDown - The root element is root
DEBUG XmlReaderCutDown - Top row has 1 items.
DEBUG XmlReaderCutDown - Node list count for id = 1
DEBUG XmlReaderCutDown -
DEBUG XmlReaderCutDown - Value was null
DEBUG XmlReaderCutDown - Node id = null
Why isn't it getting the text in the xml node?
I'm running using JDK 1.6_10

Because the element you get is the parent element of the text one, containing the text you need. To access the text of this element, you shall use getTextContent instead of getNodeValue.
For more information, see the table in the Node javadoc.

See http://java.sun.com/j2se/1.5.0/docs/api/org/w3c/dom/Node.html . Element.getNodeValue() always returns null. You should use Element.getTextContent()

Consider using XPath as an alternative to manually walking nodes:
public static void testXml(String confFile)
throws XPathExpressionException {
XPathFactory xpFactory = XPathFactory.newInstance();
XPath xpath = xpFactory.newXPath();
NodeList rows = (NodeList) xpath.evaluate("root/row",
new InputSource(confFile), XPathConstants.NODESET);
for (int i = 0; i < rows.getLength(); i++) {
Node row = rows.item(i);
String id = xpath.evaluate("button/id", row);
System.out.println("id=" + id);
}
}
public static void main(String[] args)
throws XPathExpressionException {
testXml("test.xml");
}