Develop Reference

Retrieve desired data from xml file which has same name tags

I publish some csv input file on a server and it gives me a xml file that looks like this:
<ns0:TransportationEvent xmlns:ns0="http://www.server.com/schemas/TransportationEvent.xsd">
<ns0:deviceId>4567289456</ns0:deviceId>
.....
.....
</ns0:TransportationEvent>
<ns0:TransportationEvent xmlns:ns0="http://www.server.com/schemas/TransportationEvent.xsd">
<ns0:deviceId>7965145741</ns0:deviceId>
.....
.....
</ns0:TransportationEvent>
<ns0:TransportationEvent xmlns:ns0="http://www.server.com/schemas/TransportationEvent.xsd">
<ns0:deviceId>2168744654</ns0:deviceId>
.....
.....
</ns0:TransportationEvent>
The TransportationEvent tag would be added again and again with the updated deviceId in it.
I am retrieving data from this xml using XpathFactory class and NamespaceContext class which is shown as below:
NamespaceContext ctx = new NamespaceContext() {
public String getNamespaceURI(String prefix) {
String uri;
if (prefix.equals("ns0"))
uri = "http://www.server.com/schemas/TransportationEvent.xsd";
else
uri = null;
return uri;
}
public Iterator getPrefixes(String val) {
return null;
}
// Dummy implementation - not used!
public String getPrefix(String uri) {
return null;
}
};
XPathFactory xpathFact = XPathFactory.newInstance();
XPath xpath = xpathFact.newXPath();
xpath.setNamespaceContext(ctx);
String strXpath = "//ns0:TransportationEvent/ns0:deviceId/text()";
String deviceId = xpath.evaluate(strXpath, doc);
The above code gives the value of deviceId as 4567289456. Basically it always take values from the first TransportationEvent tag.
I need to pick data from that "TransportationEvent" tag where the "deviceId" is equal to the deviceId of my choice. Something like this:
String strXpath = "//ns0:TransportationEvent[where ns0:deviceId = " + myDeviceId + "]/ns0:deviceId/text()";
I can perform this by using NodeList class and can iterate through all the "TransportationEvent" tags but then I would not be able to use the Xpath or NamespaceContext implementation. I am finding no connection between the NodeList class and the NamespaceContext class or the Xpath class.
I want to get the value of ctx which has the context of the desired TransportationEvent tag.
I know I am missing something. Could somebody help please?

You could fetch the parent node of the deviceId you are intrested in like this:
//ns0:deviceId[text()='7965145741']/parent::node()
private static final String NS0_NS = "http://www.server.com/schemas/TransportationEvent.xsd";
private static final String NS0 = "ns0";
private static final List<String> prefixes = Arrays.asList(NS0);
public void fromDocument(Document doc) throws XPathExpressionException, TransformerConfigurationException,
TransformerFactoryConfigurationError, TransformerException {
XPath xpath = XPathFactory.newInstance().newXPath();
xpath.setNamespaceContext(new NamespaceContext() {
#Override
public Iterator getPrefixes(String namespaceURI) {
return prefixes.iterator();
}
#Override
public String getPrefix(String namespaceURI) {
String res = namespaceURI.equals(NS0_NS)?NS0:null;
return res;
}
#Override
public String getNamespaceURI(String prefix) {
String res = prefix.equals(NS0)?NS0_NS:null;
return res;
}
});
XPathExpression devex = xpath.compile("//ns0:deviceId[text()='7965145741']/parent::node()");
Node node = (Node) devex.evaluate(doc,XPathConstants.NODE);
Transformer xformer = TransformerFactory.newInstance().newTransformer();
xformer.transform(new DOMSource(node),new StreamResult(System.out));
}
that's the output:
<ns0:TransportationEvent xmlns:ns0="http://www.server.com/schemas/TransportationEvent.xsd">
<ns0:deviceId>7965145741</ns0:deviceId>
</ns0:TransportationEvent>

Java, Simple XML parsing list

How can I parse this list in Java? I have List<Image> which returns from server, but I can't get a single item.
<images>
<image>
uploads/posts/2008-10/1225141003_1-21.jpg
</image>
<image>
uploads/posts/2008-10/1225141003_1-22.jpg
</image>
</images>
#Root(name = "Images") public class Images {
#ElementList(required=false, inline = true)
private List<Image> imageList;
public List<Image> getImageList() {
return imageList;
}
}
#Root(name = "image") public class Image {
//Some code.......
}

I solved this problem in this way:
#Root(name = "images")
public class Images {
#ElementList(entry = "image", required=false, inline = true)
private List<String> imageList;
public List<String> getImageList() {
return imageList;
}
}

Try this:
String inputStreamToString(InputStream is) {
String line = "";
String total = "";
BufferedReader rd = new BufferedReader(new InputStreamReader(is));
try {
while ((line = rd.readLine()) != null) {
total +=line;
}
} catch (IOException e) {
e.printStackTrace();
}
return total;
}
EDIT
If you are able to get that xml:
String responseXML = inputStreamToString(yourXMLResponseFromServer.getEntity().getContent());

To interpret XML files I have always used the org.w3c.dom.Document Interface which offers a Javascript like document modification. Check out the Documentation on the oracle website!

Use DOM and Xpath
1 Parse your String
String xml="<my_xml/>";
DocumentBuilderFactory builderFactory =DocumentBuilderFactory.newInstance();
DocumentBuilder builder = builderFactory.newDocumentBuilder();
Document document = builder.parse(new InputSource(new StringReader(xml)));
2 use an xpath
XPath xPath = XPathFactory.newInstance().newXPath();
String expression="/images/image";
XPathExpression expr = xpath.compile(expression) ;
NodeList nodes = (NodeList) expr.evaluate(document, XPathConstants.NODESET);
3 iterate
for (int k = 0; k < nodes.getLength(); k++)
{
Node nodeSegment = nodes.item(k);
if (nodeSegment.getNodeType() == Node.ELEMENT_NODE)
{
Element eElement = (Element) nodeSegment;
System.out.println("TEXT CONTENT="+eElement.getTextContent());
ALTERNATIVE:
If you know you have 1 or 2 image (s):
expression="/images/image[1]"; // first one
String value = xPath.evaluate(expression, document);
System.out.println("EVALUATE:"+value);

Reading List of Node using Xpath

this is my XML file :
<sitemesh>
<mapping path="/editor/tempPage/**" exclude="true"/>
<mapping decorator="/WEB-INF/views/decorators/detailstheme.jsp"
path="/*" exclude="false" />
</sitemesh>
I want list of mapping node with their attribute values.
this should be done using Xpath.
my xpath expression is :
expr = xpath.compile("/sitemesh/mapping");
but i am getting null in nodelist.
this is my code:
Map<String,String> map=new HashMap<String, String>();
// reading xml file
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder;
Document doc = null;
XPathExpression expr = null;
try {
builder = factory.newDocumentBuilder();
// creating input stream
doc = builder.parse(file);
XPathFactory xpf = XPathFactory.newInstance();
XPath xpath = xpf.newXPath();
expr = xpath.compile("//mapping");
} catch (Exception e) {
LOG.error("some exception message", e);
}
//------------------------------------------------------------------------
NodeList attributeElements = null;
try {
attributeElements =(NodeList)expr.evaluate(doc, XPathConstants.NODE);
} catch (XPathExpressionException e) {
LOG.error("some exception message", e);
}
System.out.println("lenght:"+attributeElements.getLength());
for (int i = 0; i < attributeElements.getLength(); i++) {
Node node=attributeElements.item(i);
System.out.println("node:"+node.getNodeValue());
NamedNodeMap attrs = node.getAttributes();
for(i = 0 ; i<attrs.getLength() ; i++) {
Attr attribute = (Attr)attrs.item(i);
System.out.println("Node Attributes : " + attribute.getName()+" = "+attribute.getValue());
}
}
//-------------------------------------------------------------------------
// writing xml file
TransformerFactory transformerFactory = TransformerFactory
.newInstance();
Transformer transformer;
try {
transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(file);// creating output
// stream
transformer.transform(source, result);
} catch (Exception e) {
LOG.error("some exception message", e);
}
return map;
i am getting null for attributeElements
i want to show values of path,decorator and exclude on JSP page.But i am unable to get list of node through xpath expression.
I want solution for reading mapping node element in Xpath.

[edit] /sitemesh/mapping also works .
The issue here is that you evaluating the express for XPathConstants.NODE while the nodeList maps to XPathConstants.NODESET. please refer below link.
http://docs.oracle.com/javase/1.5.0/docs/api/javax/xml/xpath/XPathConstants.html#NODESET
Added sample code for illustration purpose only:
public void testXpathExpr(){
String testXML = "<sitemesh><mapping path=\"/editor/tempPage/**\" exclude=\"true\"/><mapping decorator=\"/WEB-INF/views/decorators/detailstheme.jsp\" path=\"/*\" exclude=\"false\" /></sitemesh>";
NodeList nodeList = getNodeList(testXML);
}
private NodeList getNodeList(String xml) throws SAXException, IOException, ParserConfigurationException, XPathExpressionException {
DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = docFactory.newDocumentBuilder();
document = builder.parse(new ByteArrayInputStream( xml.getBytes() ) );
XPathExpression exprPath = xpath.compile(xpathExpr);
NodeList nodeList = (NodeList) exprPath.evaluate(document, XPathConstants.NODESET);;
return nodeList;
}
Hope this helps!

Your xpath works perfectly for me. Below is the sample code:
public class Parser {
public static void main(String[] args) throws Exception, Exception {
final DocumentBuilderFactory factory = DocumentBuilderFactory
.newInstance();
final DocumentBuilder builder = factory.newDocumentBuilder();
final Document doc = builder.parse("src/sitemesh.xml");
final XPathFactory xPathfactory = XPathFactory.newInstance();
final XPath xpath = xPathfactory.newXPath();
final XPathExpression expr = xpath.compile("/sitemesh/mapping");
Object node = expr.evaluate(doc, XPathConstants.NODE);
System.out.println(node);
}
}
sitemesh.xml contains your sample input.

How to read XML child node values by using a loop in java

Here is my xml code...
<flow>
<TaskID>100</TaskID>
<TaskID>101</TaskID>
<TaskID>102</TaskID>
<TaskID>103</TaskID>
</flow>
I want to know how to get taskID values in a for loop in java. Please help me...

DOM parser solution, fairly simple, no extra libraries required.
public static void main(String[] args) throws SAXException, IOException,
ParserConfigurationException {
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
String input = "<outer>";
input += "<otherstuff><TaskID>123</TaskID></otherstuff>";
input += "<flow>";
input += "<TaskID>100</TaskID>";
input += "<TaskID>101</TaskID>";
input += "<TaskID>102</TaskID>";
input += "<TaskID>103</TaskID>";
input += "</flow>";
input += "</outer>";
Document document = builder.parse(new InputSource(new StringReader(
input)));
NodeList flowList = document.getElementsByTagName("flow");
for (int i = 0; i < flowList.getLength(); i++) {
NodeList childList = flowList.item(i).getChildNodes();
for (int j = 0; j < childList.getLength(); j++) {
Node childNode = childList.item(j);
if ("TaskID".equals(childNode.getNodeName())) {
System.out.println(childList.item(j).getTextContent()
.trim());
}
}
}
}
You'd need to use a FileReader instead if your input came from a file.
Document document = builder.parse(new InputSource(new FileReader(
new File("foo.xml"))));
An alternative to getElementsByTagName() is XPath, a query language for XML, this is particularly useful if you have complicated set of conditions to match.
XPathFactory xPathfactory = XPathFactory.newInstance();
XPath xpath = xPathfactory.newXPath();
XPathExpression expr = xpath.compile("//flow/TaskID/text()");
Object result = expr.evaluate(document, XPathConstants.NODESET);
NodeList nodes = (NodeList) result;
for (int i = 0; i < nodes.getLength(); i++) {
System.out.println(nodes.item(i).getTextContent());
}
If your XML file is large, like 100s of MB / GB or you're on a low memory platform then consider a SAX parser.
String input = "<flow><TaskID>100</TaskID><TaskID>101</TaskID><TaskID>102</TaskID><TaskID>103</TaskID></flow>";
SAXParser sax = SAXParserFactory.newInstance().newSAXParser();
DefaultHandler handler = new DefaultHandler() {
private StringBuilder buffer = new StringBuilder();
#Override
public void endElement(String uri, String localName, String qName)
throws SAXException {
if ("TaskID".equals(qName)) {
System.out.println(buffer);
buffer = new StringBuilder();
}
}
#Override
public void characters(char[] ch, int start, int length)
throws SAXException {
buffer.append(ch, start, length);
}
#Override
public void startElement(String uri, String localName,
String qName, Attributes attributes) throws SAXException {
buffer = new StringBuilder();
}
};
sax.parse(new InputSource(new StringReader(input)), handler);

Here's an example using JDOM, which provides a more pleasant API over existing Java XML parsers:
import java.io.File;
import org.jdom2.*;
import org.jdom2.input.*;
public class Test {
// TODO: More appropriate exception handling :)
public static void main (String[] args) throws Exception {
SAXBuilder builder = new SAXBuilder();
Document doc = builder.build(new File("test.xml"));
Element root = doc.getRootElement();
for (Element element : root.getChildren("TaskID")) {
System.out.println(element.getText());
}
}
}
Of course, this assumes that the XML document is small enough to be loaded into memory.
(Obviously you can use the built-in libraries too, and if you're not doing much XML work then that would be fine - I just find them a bit primitive if you're doing any significant amount of work.)

With xpath Here is more information:
http://www.vogella.com/articles/JavaXML/article.html

I personally use JDOM library for all my XML manipulation.. Below is how I would do it;
String xml = "<flow> " +
"<TaskID>100</TaskID>" +
"<TaskID>101</TaskID>" +
"<TaskID>102</TaskID>" +
"<TaskID>103</TaskID>" +
"</flow>";
org.jdom.Document doc = new SAXBuilder().build(new StringReader(xml));
org.jdom.Element rootElement = doc.getRootElement();
List<Element> eles = rootElement.getChildren("TaskID");
for(Element el : eles)
System.out.println(el.getName()+" : "+el.getValue());
You can get it's documentation here: http://www.jdom.org/

Read Xml Children with SAX
<?xml version="1.0"?>
<Patriarch>
<name>Bill</name>
<wife>
<name>Vi</name>
</wife>
<son>
<name>Bill</name>
</son>
<daughter>
<name>Jeri</name>
<husband>
<name>Mark</name>
</husband>
<son>
<name>Greg</name>
</son>
<son>
<name>Tim</name>
</son>
<son>
<name>Mark</name>
</son>
<son>
<name>Josh</name>
<wife>
<name>Kristine</name>
</wife>
<son>
<name>Blake</name>
</son>
<daughter>
<name>Liah</name>
</daughter>
</son>
</daughter>
</Patriarch>
And Java code:
public class ParseXmlSAX {
public static void main(String[] args) {
new ParseXmlSAX("file.xml");
}
public ParseXmlSAX(final String file) {
try {
SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser saxParser = factory.newSAXParser();
DefaultHandler handler = new DefaultHandler() {
String key = null;
public void startElement(String uri, String localName, String qName, Attributes attributes)
throws SAXException {
if (key == null)
key = "|";
else
key += qName + "|";
}
public void endElement(String uri, String localName, String qName) throws SAXException {
if (!key.equals("|"))
key = key.substring(0, key.lastIndexOf(qName));
}
public void characters(char ch[], int start, int length) throws SAXException {
String conteudo = new String(ch, start, length).trim();
if (!conteudo.isEmpty()) {
System.out.println(key + " = " + conteudo);
}
}
};
saxParser.parse(this.getClass().getResourceAsStream(file), handler);
} catch (Exception e) {
e.printStackTrace();
}
}
}

public class Modifier {
public void modifyXML() {
String strSrcFile = "E:\\projects\\input\\sample.xml";
String strOutputFile = "E:\\projects\\output\\sample.xml";
try {
DocumentBuilderFactory docFactory = DocumentBuilderFactory
.newInstance();
DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
Document doc = docBuilder.parse(strSrcFile);
Node company = doc.getFirstChild();
System.out.println(company.hasChildNodes());
NodeList nl = company.getChildNodes();
for (int i = 0; i < nl.getLength(); i++) {
Node node = nl.item(i);
// System.out.println("inner node::"+node.getNodeName());
if (node.hasChildNodes()) {
System.out.println("outer node::" + node.getNodeName());
readChildNodes(node);
} else {
}
}
TransformerFactory transformerFactory = TransformerFactory
.newInstance();
Transformer transformer = transformerFactory.newTransformer();
DOMSource source = new DOMSource(doc);
StreamResult result = new StreamResult(new File(strOutputFile));
transformer.transform(source, result);
} catch (Exception ee) {
ee.printStackTrace();
}
// Get the root element
}
public void readChildNodes(Node node)
{
NodeList nl = node.getChildNodes();
for (int i = 0; i < nl.getLength(); i++) {
Node innernode = nl.item(i);
//System.out.println("mediam stage node::"+innernode.getNodeName());
if (innernode.hasChildNodes()) {
System.out.println("inner node::"+innernode.getNodeName());
readChildNodes(innernode);
}
else{
System.out.println("node dont have childs node::"+innernode.getNodeName());
}
}
}
public void replaceGraphicCode(Node innernode) {
NamedNodeMap attr = innernode.getAttributes();
Node nodeAttr = attr.getNamedItem("id");
String IDvalue = nodeAttr.getTextContent();
// nodeAttr.setTextContent("2");
}
public void replaceOriginator(Node innernode) {
NamedNodeMap attr = innernode.getAttributes();
Node nodeAttr = attr.getNamedItem("enterpriseCode");
}
public static void main(String[] args) {
Modifier objModifier = new Modifier();
objModifier.modifyXML();
}
}

Xpath can't query tag with namespace

I have xml like below (Google API), but can't get gphoto:id element value. How to do that ? Notice: When i'm using domFactory.setNamespaceAware(true);, /feed/entry xpath stops working.
<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom"
xmlns:gphoto="http://schemas.google.com/photos/2007"
xmlns:media="http://search.yahoo.com/mrss/"
xmlns:openSearch="http://a9.com/-/spec/opensearchrss/1.0/">
<entry>
<title type="text">Test</title>
<author>
<name>username</name>
<uri>https://picasaweb.google.com/113422203255202384532</uri>
</author>
<gphoto:id>57060151229174417</gphoto:id>
</entry>
</feed>
Java
NodeList nodes = (NodeList) path(body, "/feed/entry", XPathConstants.NODESET);
for (int i = 0; i < nodes.getLength(); i++) {
Node n = nodes.item(i);
XPath xpath = XPathFactory.newInstance().newXPath();
// empty :(
System.out.println(
xpath.evaluate("id[namespace-uri()='http://schemas.google.com/photos/2007']",n)
);
// empty too :(
System.out.println(
xpath.evaluate("gphoto:id",n)
);
// ok
System.out.println(
xpath.evaluate("author",n)
);
l.add(new Album("", "", ""));
}
path method
private Object path(String content, String path, QName returnType) {
try {
DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document doc = builder.parse(new InputSource(new StringReader(content)));
XPath xpath = XPathFactory.newInstance().newXPath();
XPathExpression expr = xpath.compile(path);
return expr.evaluate(doc, returnType);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
SOLVED according to #gioele answer path() method is now like below:
private Object path(String content, String path, QName returnType) {
try {
domFactory.setNamespaceAware(true);
DocumentBuilder builder = domFactory.newDocumentBuilder();
Document doc = builder.parse(new InputSource(new StringReader(content)));
XPath xpath = XPathFactory.newInstance().newXPath();
NamespaceContext nsContext = new NamespaceContext() {
#Override
public Iterator getPrefixes(String namespaceURI) {
return null;
}
#Override
public String getPrefix(String namespaceURI) {
return null;
}
#Override
public String getNamespaceURI(String prefix) {
if ("gphoto".equals(prefix))
return "http://schemas.google.com/photos/2007";
if ("media".equals(prefix))
return "http://search.yahoo.com/mrss/";
if("".equals(prefix))
return "http://www.w3.org/2005/Atom";
throw new IllegalArgumentException(prefix);
}
};
xpath.setNamespaceContext(nsContext);
XPathExpression expr = xpath.compile(path);
return expr.evaluate(doc, returnType);
} catch (Exception e) {
e.printStackTrace();
}
return null;
}

Before compiling your xpath you need to register a NamespaceContext.
Have a look at the code in https://github.com/gioele/xpathapi-jaxp/blob/master/src/main/java/it/svario/xpathapi/jaxp/NodeNamespaceContext.java.
If you want to avoid all these complications, you can use the XPathAPI library:
Map<String, String> nsMap = new HashMap<String, String>();
nsMap.put(XMLConstants.DEFAULT_NS_PREFIX, "http://www.w3.org/2005/Atom");
nsMap.put("gphoto", "http://schemas.google.com/photos/2007");
List<Node> entries = XPathAPI.selectListOfNodes(doc, "/feed/entry", nsMap);
for (Node entry : entries) {
String id = XPathAPI.selectSingleNodeAsString(entry, "gphoto:id", nsMap);
// or, if you prefer a Node
// Node id = XPathAPI.selectSingleNode(entry, "gphoto:id", nsMap);
}
Disclaimer: I am the creator of XPathAPI-JAXP.

A much easier way to deal with the namespace issue is just to redirect the call from the NamespaceContext to the document lookupNamespaceURI() method. This will return "http://search.yahoo.com/mrss/" when called with "media" etc...
xPath.setNamespaceContext(new NamespaceContext() {
#Override
public String getNamespaceURI(String prefix) {
return doc.lookupNamespaceURI(prefix);
}
#Override
public Iterator<?> getPrefixes(String arg0) {
return null;
}
#Override
public String getPrefix(String arg0) {
return null;
}
});