Develop Reference

How to get a specifc information for an XML file

I have a large XML file and below is an extract from it:
...
<LexicalEntry id="Ait~ifAq_1">
<Lemma partOfSpeech="n" writtenForm="اِتِّفاق"/>
<Sense id="Ait~ifAq_1_tawaAfuq_n1AR" synset="tawaAfuq_n1AR"/>
<WordForm formType="root" writtenForm="وفق"/>
</LexicalEntry>
<LexicalEntry id="tawaA&um__1">
<Lemma partOfSpeech="n" writtenForm="تَوَاؤُم"/>
<Sense id="tawaA&um__1_AinosijaAm_n1AR" synset="AinosijaAm_n1AR"/>
<WordForm formType="root" writtenForm="وأم"/>
</LexicalEntry>
<LexicalEntry id="tanaAgum_2">
<Lemma partOfSpeech="n" writtenForm="تناغُم"/>
<Sense id="tanaAgum_2_AinosijaAm_n1AR" synset="AinosijaAm_n1AR"/>
<WordForm formType="root" writtenForm="نغم"/>
</LexicalEntry>
<Synset baseConcept="3" id="tawaAfuq_n1AR">
<SynsetRelations>
<SynsetRelation relType="hyponym" targets="AinosijaAm_n1AR"/>
<SynsetRelation relType="hyponym" targets="AinosijaAm_n1AR"/>
<SynsetRelation relType="hypernym" targets="ext_noun_NP_420"/>
</SynsetRelations>
<MonolingualExternalRefs>
<MonolingualExternalRef externalReference="13971065-n" externalSystem="PWN30"/>
</MonolingualExternalRefs>
</Synset>
...
I want to extract specific information from it. For a given writtenForm whether from <Lemma> or <WordForm>, the programme takes the value of synset from <Sense> of that writtenForm (same <LexicalEntry>) and searches for all the value id of <Synset> that have the same value as the synset from <Sense>. After that, the programme gives us all the relations of that Synset, i.e it displays the value of relType and returns to <LexicalEntry> and looks for the value synset of <Sense> who have the same value of targets then displays its writtenForm.
I think it's a little bit complicated but the result should be like this:
اِتِّفاق hyponym تَوَاؤُم, اِنْسِجام
One of the solutions is the use of the Stream reader because of the memory consumption. but I don't how should I proceed to get what I want. help me please.

The SAX Parser is different from DOM Parser.It is looking only on the current item it can't see on the future items until they become the current item . It is one of the many you can use when XML file is extremely big . Instead of it there are many out there . To name a few:
SAX PARSER
DOM PARSER
JDOM PARSER
DOM4J PARSER
STAX PARSER
You can find for all them tutorials here.
In my opinion after learning it go straight to use DOM4J or JDOM for commercial product.
The logic of SAX Parser is that you have a MyHandler class which is extending DefaultHandler and #Overrides some of it's methods:
XML FILE:
<?xml version="1.0"?>
<class>
<student rollno="393">
<firstname>dinkar</firstname>
<lastname>kad</lastname>
<nickname>dinkar</nickname>
<marks>85</marks>
</student>
<student rollno="493">
<firstname>Vaneet</firstname>
<lastname>Gupta</lastname>
<nickname>vinni</nickname>
<marks>95</marks>
</student>
<student rollno="593">
<firstname>jasvir</firstname>
<lastname>singn</lastname>
<nickname>jazz</nickname>
<marks>90</marks>
</student>
</class>
Handler class:
import org.xml.sax.Attributes;
import org.xml.sax.SAXException;
import org.xml.sax.helpers.DefaultHandler;
public class UserHandler extends DefaultHandler {
boolean bFirstName = false;
boolean bLastName = false;
boolean bNickName = false;
boolean bMarks = false;
#Override
public void startElement(String uri,
String localName, String qName, Attributes attributes)
throws SAXException {
if (qName.equalsIgnoreCase("student")) {
String rollNo = attributes.getValue("rollno");
System.out.println("Roll No : " + rollNo);
} else if (qName.equalsIgnoreCase("firstname")) {
bFirstName = true;
} else if (qName.equalsIgnoreCase("lastname")) {
bLastName = true;
} else if (qName.equalsIgnoreCase("nickname")) {
bNickName = true;
}
else if (qName.equalsIgnoreCase("marks")) {
bMarks = true;
}
}
#Override
public void endElement(String uri,
String localName, String qName) throws SAXException {
if (qName.equalsIgnoreCase("student")) {
System.out.println("End Element :" + qName);
}
}
#Override
public void characters(char ch[],
int start, int length) throws SAXException {
if (bFirstName) {
System.out.println("First Name: "
+ new String(ch, start, length));
bFirstName = false;
} else if (bLastName) {
System.out.println("Last Name: "
+ new String(ch, start, length));
bLastName = false;
} else if (bNickName) {
System.out.println("Nick Name: "
+ new String(ch, start, length));
bNickName = false;
} else if (bMarks) {
System.out.println("Marks: "
+ new String(ch, start, length));
bMarks = false;
}
}
}
Main Class :
import java.io.File;
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 SAXParserDemo {
public static void main(String[] args){
try {
File inputFile = new File("input.txt");
SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser saxParser = factory.newSAXParser();
UserHandler userhandler = new UserHandler();
saxParser.parse(inputFile, userhandler);
} catch (Exception e) {
e.printStackTrace();
}
}
}

XPath was designed for exactly this. Java provides support for it in the javax.xml.xpath package.
To do what you want, the code will look something like this:
List<String> findRelations(String word,
Path xmlFile)
throws XPathException {
String xmlLocation = xmlFile.toUri().toASCIIString();
XPath xpath = XPathFactory.newInstance().newXPath();
xpath.setXPathVariableResolver(
name -> (name.getLocalPart().equals("word") ? word : null));
String id = xpath.evaluate(
"//LexicalEntry[WordForm/#writtenForm=$word or Lemma/#writtenForm=$word]/Sense/#synset",
new InputSource(xmlLocation));
xpath.setXPathVariableResolver(
name -> (name.getLocalPart().equals("id") ? id : null));
NodeList matches = (NodeList) xpath.evaluate(
"//Synset[#id=$id]/SynsetRelations/SynsetRelation",
new InputSource(xmlLocation),
XPathConstants.NODESET);
List<String> relations = new ArrayList<>();
int matchCount = matches.getLength();
for (int i = 0; i < matchCount; i++) {
Element match = (Element) matches.item(i);
String relType = match.getAttribute("relType");
String synset = match.getAttribute("targets");
xpath.setXPathVariableResolver(
name -> (name.getLocalPart().equals("synset") ? synset : null));
NodeList formNodes = (NodeList) xpath.evaluate(
"//LexicalEntry[Sense/#synset=$synset]/WordForm/#writtenForm",
new InputSource(xmlLocation),
XPathConstants.NODESET);
int formCount = formNodes.getLength();
StringJoiner forms = new StringJoiner(",");
for (int j = 0; j < formCount; j++) {
forms.add(
formNodes.item(j).getNodeValue());
}
relations.add(
String.format("%s %s %s", word, relType, forms));
}
return relations;
}
Some basic XPath information:
XPath uses a single file-path-like string to match parts of an XML document. The parts can be any structural part of the document: text, elements, attributes, even things like comments.
A Java XPath expression can attempt to match exactly one part, or several parts, or can even concatenate all matched parts as a String.
In an XPath expression, a name by itself represents an element. For example, WordForm in XPath means any <WordForm …> element in the XML document.
A name starting with # represents an attribute. For example, #writtenForm refers to any writtenForm=… attribute in the XML document.
A slash indicates a parent and child in an XML document. LexicalEntry/Lemma means any <Lemma> element which is a direct child of a <LexicalEntry> element. Synset/#id means the id=… attribute of any <Synset> element.
Just as a path starting with / indicates an absolute (root-relative) path in Unix, an XPath starting with a slash indicates an expression relative to the root of an XML document.
Two slashes means a descendant which may be a direct child, a grandchild, a great-grandchild, etc. Thus, //LexicalEntry means any LexicalEntry in the document; /LexicalEntry only matches a LexicalEntry element which is the root element.
Square brackets indicate match qualifiers. Synset[#baseConcept='3'] matches any <Synset> element with an baseConcept attribute whose value is the string "3".
XPath can refer to variables, which are defined externally, using Unix-shell-like $ substitutions, like $word. How those variables are passed to an XPath expression depends on the engine. Java uses the setXPathVariableResolver method. Variable names are in a completely separate namespace from node names, so it is of no consequence if a variable name is the same as an element name or attribute name in the XML document.
So, the XPath expressions in the code mean:
//LexicalEntry[WordForm/#writtenForm=$word or Lemma/#writtenForm=$word]/Sense/#synset
Match any <LexicalEntry> element anywhere in the XML document which has either
a WordForm child with a writtenForm attribute whose value is equal to the word variable
a Lemma child with a writtenForm attribute whose value is equal to the word variable
and for every such <LexicalEntry> element, return the value of the synset attribute of any <Sense> element which is a direct child of the <LexicalEntry> element.
The word variable is defined externally, by an xpath.setXPathVariableResolver, right before the XPath expression is evaluated.
//Synset[#id=$id]/SynsetRelations/SynsetRelation
Match any <Synset> element anywhere in the XML document whose id attribute is equal to the id variable. For each such <Synset> element, look for any direct SynsetRelations child element, and return each of its direct SynsetRelation children.
The id variable is defined externally, by an xpath.setXPathVariableResolver, right before the XPath expression is evaluated.
//LexicalEntry[Sense/#synset=$synset]/WordForm/#writtenForm
Match any <LexicalEntry> element anywhere in the XML document which has a <Sense> child element which has a synset attribute whose value is identical to the synset variable. For each matched element, find any <WordForm> child element and return that element’s writtenForm attribute.
The synset variable is defined externally, by an xpath.setXPathVariableResolver, right before the XPath expression is evaluated.
Logically, what the above should amount to is:
Locate the synset value for the requested word.
Use the synset value to locate SynsetRelation elements.
Locate writtenForm values corresponding to the targets value of each matched SynsetRelation.

If this XML file is too large to represent in memory, use SAX.
You will want to write your SAX parser to maintain a location. To do this, I typically use a StringBuffer, but a Stack of Strings would work just as nicely. This portion will be important because it will permit you to keep track of the path back to the root of the document, which will allow you to understand where in the document you are at a given point in time (useful when trying to only extract a little information).
The main logic flow looks like:
1. When entering a node, add the node's name to the stack.
2. When exiting a node, pop the node's name (top element) off the stack.
3. To know your location, read your current branch of the XML from the bottom of the stack to the top of the stack.
4. When entering a region you care about, clear the buffer you will capture the characters into
5. When exiting a region you care about, flush the buffer into the data structure you will return back as your output.
This way you can efficiently skip over all the branches of the XML tree that you don't care about.

Add prefix to the default namespace "xmlns"

I am trying to add prefix to the default namespace of the DOM object, I was unable to achieve that, I have created a new node with no default Namesapce in it printed it to make sure no default namespace exists. Added an new attribute with a namespace with a prefix.
I was able to add the new attribute, but was not able to remove the default namespace. Can you tell me on how to achieve it.
for (int j = 0; j < ODMNode1.getAttributes().getLength(); j++) {
System.out.println("Attribute: "
+ ODMNode1.getAttributes().item(j).getNodeName() + " = "
+ ODMNode1.getAttributes().item(j).getNodeValue());
if (ODMNode1.getAttributes().item(j).getNodeName().equals("xmlns") &&
ODMNode1.getAttributes().item(j).getNodeValue().equals("http://www.com.org"))'{
System.out.println("Beforev Removed"+ ODMNode1.getAttributes().item(j).getNodeName());
Element element = (Element) ODMNode1;
element.removeAttribute("xmlns");
System.out.println("Removed"+ element.getAttribute("xmlns"));
System.out.println("After Removed"+ ODMNode1.getAttributes().item(j).getNodeName());
}
}

In the W3C DOM model, you can't change the namespace of a node. If you want a node with the same local name but a different namespace (including no namespace) then you have to create a new node. XSLT can help with that.

Remove empty namespace in java using DOM

<Request>
<EMPId>?</EMPId>
</Request>
I know this is a repeated question, but i would like to post it again as i dint get a convincing answer from any of the threads i went through.
My ultimate aim is to add the XML given above as the Body content of a SOAP message.
You can have a look at the following link to see how i am doing it.
Namespace related error on creating SOAP Request
It worked fine when i was using the Websphere Application Server 7.0 library.JRE is also present, forgot to include in screen shot.
Since i have to export it as a jar and run it as a stand alone application, i have to remove the dependency of 'Websphere Application Server 7.0 library'. Because, by keeping this library, my jar size will go above 100MB. So i thought of taking only the library which i needed.
'com.ibm.ws.prereq.soap.jar'
Now the issue is, the Request tag of the generated SOAP request is coming in following format.
<Request xmlns="">
<EMPId>?</EMPId>
</Request>
I am able to create a 'org.w3c.dom.Document' representation for the generated SOAP message.
Now, can any one tell me how can I delete the xmlns="" from Request tag.

The simplest way what i found is:
first:
in child set nasmespace as in root:
second:
remove namespace
Document doc = new Document();
Namespace xmlns = Namespace.getNamespace("http://www.microsoft.com/networking/WLAN/profile/v1");
Element rootXML = new Element("WLANProfile", xmlns);
Element nameXML = new Element("name");
nameXML.addContent(name);
rootXML.addContent(nameXML);
//below solution
nameXML.setNamespace(xmlns);
nameXML.removeNamespaceDeclaration(xmlns);

Finally I found several solutions of the described problem.
First, you can remove all namespaces from all xml using this answer.
Second, if you do not need to remove all namespaces in Xml, but only empty ones, they arise due to the fact that some namespace is written in the root elements, which is not in the child. For example:
<ЭДПФР xmlns="http://пф.рф/КСАФ/2018-04-03"
xmlns:АФ4="xx"...>
<КСАФ xmlns="">
...
</КСАФ>
So you need to set the same namespace for all children of root elements. It can be done using this code (call setTheSameNamespaceForChildren(rootElement) for root element before saving):
private static final String namespaceKey = "xmlns";
private static String namespaceValue;
public static void setTheSameNamespaceForChildren(Element rootEl) {
namespaceValue = rootEl.getAttribute(namespaceKey);
NodeList list = rootEl.getChildNodes();
for (int i = 0; i < list.getLength(); i++) {
Node child = list.item(i);
setTheSameNamespaceRecursively(child);
}
}
private static void setTheSameNamespaceRecursively(Node node) {
if (node.getNodeType() == Node.ELEMENT_NODE) {
boolean isChanged = setTheSameNamespace((Element) node);
if (isChanged) {
NodeList list = node.getChildNodes();
for (int i = 0; i < list.getLength(); i++) {
Node child = list.item(i);
setTheSameNamespaceRecursively(child);
}
}
}
}
private static boolean setTheSameNamespace(Element node) {
String curValue = node.getAttribute(namespaceKey);
if (curValue.length() == 0) {
node.setAttribute(namespaceKey, namespaceValue);
return true;
}
return false;
}

Java - parse xml string with variable tagnames?

I'm trying to parse an XML string, and the tagnames are variable; I haven't seen any examples on how to pull the information out without knowing them. For example, I will always know the <response> and <data> tags below, but what falls inside/outside of them could be anything from <employee> to you name it.
<?xml version="1.0" encoding="UTF-8"?>
<response>
<generic>
....
</generic>
<data>
<employee>
<name>Seagull</name>
<id>3674</id>
<age>34</age>
</employee>
<employee>
<name>Robin</name>
<id>3675</id>
<age>25</age>
</employee>
</data>
</response>

You could parse it into a generic dom object and traverse it. For example, you could use dom4j to do this.
From the dom4j quick start guide:
public void treeWalk(Document document) {
treeWalk( document.getRootElement() );
}
public void treeWalk(Element element) {
for ( int i = 0, size = element.nodeCount(); i < size; i++ ) {
Node node = element.node(i);
if ( node instanceof Element ) {
treeWalk( (Element) node );
}
else {
// do something....
}
}
}
public Document parse(URL url) throws DocumentException {
SAXReader reader = new SAXReader();
Document document = reader.read(url);
return document;
}

I have seen similar situation in the projects.
If you are going to deal with large XMLs, you can use Stax or Sax parser to read the XML. On every step (like on reaching end element), enter the data into a Map or a dta structure of your choice, where you keep tag names as the key and value as value in the Map. Finally once you have the parsing done, use this Map to figure out which object to build as finally you would have a proper entity representation of the information in the XML
If XML is small,use DOM and directly build the entity object by reading the specific tag (like employee> or use XPATh to where you expect the tag to be present, giving you hint of the entity. Build that object directly by reading the specific information from the XML.

How to add a node to XML with XMLBeans XmlObject

My goal is to take an XML string and parse it with XMLBeans XmlObject and add a few child nodes.
Here's an example document (xmlString),
<?xml version="1.0"?>
<rootNode>
<person>
<emailAddress>joefoo#example.com</emailAddress>
</person>
</rootNode>
Here's the way I'd like the XML document to be after adding some nodes,
<?xml version="1.0"?>
<rootNode>
<person>
<emailAddress>joefoo#example.com</emailAddress>
<phoneNumbers>
<home>555-555-5555</home>
<work>555-555-5555</work>
<phoneNumbers>
</person>
</rootNode>
Basically, just adding the <phoneNumbers/> node with two child nodes <home/> and <work/>.
This is as far as I've gotten,
XmlObject xml = XmlObject.Factory.parse(xmlString);
Thank you

Here is an example of using the XmlCursor to insert new elements. You can also get a DOM Node for an XmlObject and using those APIs.
import org.apache.xmlbeans.*;
/**
* Adding nodes to xml using XmlCursor.
* #see http://xmlbeans.apache.org/docs/2.4.0/guide/conNavigatingXMLwithCursors.html
* #see http://xmlbeans.apache.org/docs/2.4.0/reference/org/apache/xmlbeans/XmlCursor.html
*/
public class AddNodes
{
public static final String xml =
"<rootNode>\n" +
" <person>\n" +
" <emailAddress>joefoo#example.com</emailAddress>\n" +
" </person>\n" +
"</rootNode>\n";
public static XmlOptions saveOptions = new XmlOptions().setSavePrettyPrint().setSavePrettyPrintIndent(2);
public static void main(String[] args) throws XmlException
{
XmlObject xobj = XmlObject.Factory.parse(xml);
XmlCursor cur = null;
try
{
cur = xobj.newCursor();
// We could use the convenient xobj.selectPath() or cur.selectPath()
// to position the cursor on the <person> element, but let's use the
// cursor's toChild() instead.
cur.toChild("rootNode");
cur.toChild("person");
// Move to </person> end element.
cur.toEndToken();
// Start a new <phoneNumbers> element
cur.beginElement("phoneNumbers");
// Start a new <work> element
cur.beginElement("work");
cur.insertChars("555-555-5555");
// Move past the </work> end element
cur.toNextToken();
// Or insert a new element the easy way in one step...
cur.insertElementWithText("home", "555-555-5555");
}
finally
{
if (cur != null) cur.dispose();
}
System.out.println(xobj.xmlText(saveOptions));
}
}

XMLBeans seems like a hassle, here's a solution using XOM:
import nu.xom.*;
Builder = new Builder();
Document doc = builder.build(new java.io.StringBufferInputStream(inputXml));
Nodes nodes = doc.query("person");
Element homePhone = new Element("home");
homePhone.addChild(new Text("555-555-5555"));
Element workPhone = new Element("work");
workPhone.addChild(new Text("555-555-5555"));
Element phoneNumbers = new Element("phoneNumbers");
phoneNumbers.addChild(homePhone);
phoneNumbers.addChild(workPhone);
nodes[0].addChild(phoneNumbers);
System.out.println(doc.toXML()); // should print modified xml

It may be a little difficult to manipulate the objects using just the XmlObject interface. Have you considered generating the XMLBEANS java objects from this xml?
If you don't have XSD for this schema you can generate it using XMLSPY or some such tools.
If you just want XML manipulation (i.e, adding nodes) you could try some other APIs like jdom or xstream or some such thing.

Method getDomNode() gives you access to the underlying W3C DOM Node. Then you can append childs using W3C Document interface.