Get XML only immediate children elements by name
You can use XPath for this, using two path to get them and process them differently.
To get the <file> nodes direct children of <notification> use //notification/file and for the ones in <group> use //groups/group/file.
This is a simple sample:
public class SO10689900 {
public static void main(String[] args) throws Exception {
DocumentBuilder db = DocumentBuilderFactory.newInstance().newDocumentBuilder();
Document doc = db.parse(new InputSource(new StringReader("<notifications>\n" +
" <notification>\n" +
" <groups>\n" +
" <group name=\"zip-group.zip\" zip=\"true\">\n" +
" <file location=\"C:\\valid\\directory\\\" />\n" +
" <file location=\"C:\\this\\file\\doesn't\\exist.grr\" />\n" +
" <file location=\"C:\\valid\\file\\here.txt\" />\n" +
" </group>\n" +
" </groups>\n" +
" <file location=\"C:\\valid\\file.txt\" />\n" +
" <file location=\"C:\\valid\\file.xml\" />\n" +
" <file location=\"C:\\valid\\file.doc\" />\n" +
" </notification>\n" +
"</notifications>")));
XPath xpath = XPathFactory.newInstance().newXPath();
XPathExpression expr1 = xpath.compile("//notification/file");
NodeList nodes = (NodeList)expr1.evaluate(doc, XPathConstants.NODESET);
System.out.println("Files in //notification");
printFiles(nodes);
XPathExpression expr2 = xpath.compile("//groups/group/file");
NodeList nodes2 = (NodeList)expr2.evaluate(doc, XPathConstants.NODESET);
System.out.println("Files in //groups/group");
printFiles(nodes2);
}
public static void printFiles(NodeList nodes) {
for (int i = 0; i < nodes.getLength(); ++i) {
Node file = nodes.item(i);
System.out.println(file.getAttributes().getNamedItem("location"));
}
}
}
It should output:
Files in //notification
location="C:\valid\file.txt"
location="C:\valid\file.xml"
location="C:\valid\file.doc"
Files in //groups/group
location="C:\valid\directory\"
location="C:\this\file\doesn't\exist.grr"
location="C:\valid\file\here.txt"
If you stick with the DOM API
NodeList nodeList = doc.getElementsByTagName("notification")
.item(0).getChildNodes();
// get the immediate child (1st generation)
for (int i = 0; i < nodeList.getLength(); i++)
switch (nodeList.item(i).getNodeType()) {
case Node.ELEMENT_NODE:
Element element = (Element) nodeList.item(i);
System.out.println("element name: " + element.getNodeName());
// check the element name
if (element.getNodeName().equalsIgnoreCase("file"))
{
// do something with you "file" element (child first generation)
System.out.println("element name: "
+ element.getNodeName() + " attribute: "
+ element.getAttribute("location"));
}
break;
}
Our first task is to get an element "Notification" (in this case the first -item (0)-) and all of its children:
NodeList nodeList = doc.getElementsByTagName("notification")
.item(0).getChildNodes();
(later you can work with all elements using getting all the elements).
For every child of "Notification":
for (int i = 0; i < nodeList.getLength(); i++)
you first get its type in order to see whether it is an element:
switch (nodeList.item(i).getNodeType()) {
case Node.ELEMENT_NODE:
//.......
break;
}
If it's the case, then you got your children "file" , that are not grand children "Notification"
and your can check them out:
if (element.getNodeName().equalsIgnoreCase("file"))
{
// do something with you "file" element (child first generation)
System.out.println("element name:"
+ element.getNodeName() + " attribute: "
+ element.getAttribute("location"));
}
and the ouptut is:
element name: file
element name:file attribute: C:\valid\file.txt
element name: file
element name:file attribute: C:\valid\file.xml
element name: file
element name:file attribute: C:\valid\file.doc
Well, the DOM solution to this question is actually pretty simple, even if it's not too elegant.
When I iterate through the filesNodeList, which is returned when I call notificationElement.getElementsByTagName("file"), I just check whether the parent node's name is "notification". If it isn't then I ignore it because that will be handled by the <group> element. Here's my code solution:
for (int j = 0; j < filesNodeList.getLength(); j++) {
Element fileElement = (Element) filesNodeList.item(j);
if (!fileElement.getParentNode().getNodeName().equals("notification")) {
continue;
}
...
}
I realise you found something of a solution to this in May @kentcdodds but I just had a fairly similar problem which I've now found, I think (perhaps in my usecase, but not in yours), a solution to.
a very simplistic example of my XML format is shown below:-
<?xml version="1.0" encoding="utf-8"?>
<rels>
<relationship num="1">
<relationship num="2">
<relationship num="2.1"/>
<relationship num="2.2"/>
</relationship>
</relationship>
<relationship num="1.1"/>
<relationship num="1.2"/>
</rels>
As you can hopefully see from this snippet, the format I want can have N-levels of nesting for [relationship] nodes, so obviously the problem I had with Node.getChildNodes() was that I was getting all nodes from all levels of the hierarchy, and without any sort of hint as to Node depth.
Looking at the API for a while , I noticed there are actually two other methods that might be of some use:-
- Node.getFirstChild()
- Node.getNextSibling()
Together, these two methods seemed to offer everything that was required to get all of the immediate descendant elements of a Node. The following jsp code should give a fairly basic idea of how to implement this. Sorry for the JSP. I'm rolling this into a bean now but didn't have time to create a fully working version from picked apart code.
<%@page import="javax.xml.parsers.DocumentBuilderFactory,
javax.xml.parsers.DocumentBuilder,
org.w3c.dom.Document,
org.w3c.dom.NodeList,
org.w3c.dom.Node,
org.w3c.dom.Element,
java.io.File" %><%
try {
File fXmlFile = new File(application.getRealPath("/") + "/utils/forms-testbench/dom-test/test.xml");
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(fXmlFile);
doc.getDocumentElement().normalize();
Element docEl = doc.getDocumentElement();
Node childNode = docEl.getFirstChild();
while( childNode.getNextSibling()!=null ){
childNode = childNode.getNextSibling();
if (childNode.getNodeType() == Node.ELEMENT_NODE) {
Element childElement = (Element) childNode;
out.println("NODE num:-" + childElement.getAttribute("num") + "<br/>\n" );
}
}
} catch (Exception e) {
out.println("ERROR:- " + e.toString() + "<br/>\n");
}
%>
This code would give the following output, showing only direct child elements of the initial root node.
NODE num:-1
NODE num:-1.1
NODE num:-1.2
Hope this helps someone anyway. Cheers for the initial post.