Develop Reference

Xml parsing in Android with XPath

Perhaps I'm going about this the wrong way, I'm trying to parse a gpx file, I've never parsed xml format in android before, I've tried a few different ways and can't seem to get any results.
The xml is at the bottom (a snippet its really long!). I want the trkpt nodes, actually the only data I need it lat, lon and time.
The last method I tired was using Xpath. It always returns an empty node list.
try {
InputSource inputSrc = new InputSource(context.getResources().openRawResource(R.raw.sample_track));
XPath xpath = XPathFactory.newInstance().newXPath();
String expression = "//trkpt";
NodeList nodes = (NodeList)xpath.evaluate(expression, inputSrc, XPathConstants.NODESET);
also tried this:
private List<Location> decodeGPX(Context context) {
DocumentBuilderFactory documentBuilderFactory = DocumentBuilderFactory.newInstance();
try {
DocumentBuilder documentBuilder = documentBuilderFactory.newDocumentBuilder();
Document document = documentBuilder.parse(context.getResources().openRawResource(R.raw.sample_track));
Element elementRoot = document.getDocumentElement();
NodeList nodelist_trk = elementRoot.getElementsByTagName("trk");
for (int j = 0; j < nodelist_trk.getLength(); j++) {
Node node = nodelist_trk.item(j);
if (node.getNodeName().equals("trkseg")) {
NodeList trkpntList = node.getChildNodes();
XML:
<?xml version="1.0" ?>
<gpx>
<name><![CDATA[WassonPeak]]></name>
<desc><![CDATA[Wasson Peak is a classic hike in Saguaro National Park West. The destination is the high point of the Tucson Mountains at 4687 feet, Wasson peak. This map is of the eastern approach, from the trailhead at the end of Camino del Cerro.]]></desc>
<author><![CDATA[Scott Morris]]></author>
<email><![CDATA[smorris#topofusion.com]]></email>
<url><![CDATA[http://www.topofusion.com]]></url>
<urlname><![CDATA[TopoFusion Home Page]]></urlname>
<keywords><![CDATA[Wasson Saguaro West]]></keywords>
<bounds maxlat="32.288840" minlon="-111.150076" minlat="32.265301" maxlon="-111.120627"/>
<wpt lat="32.273882" lon="-111.147150">
<name><![CDATA[Wasson Peak]]></name>
<cmt><![CDATA[]]></cmt>
</wpt>
<wpt lat="32.288552" lon="-111.120627">
<name><![CDATA[Camino Del Cerro Trailhead]]></name>
<cmt><![CDATA[]]></cmt>
</wpt>
<wpt lat="32.265516" lon="-111.143047">
<name><![CDATA[Saddle]]></name>
<cmt><![CDATA[]]></cmt>
</wpt>
<trk>
<url><![CDATA[http://www.topofusion.com]]></url>
<urlname><![CDATA[TopoFusion Home Page]]></urlname>
<trkseg>
<trkpt lat="32.288668" lon="-111.120915">
<ele>847.058838</ele>
<time>2002-11-20T23:05:06Z</time>
</trkpt>
<trkpt lat="32.288668" lon="-111.120915">
<ele>847.539551</ele>
<time>2002-11-20T23:05:07Z</time>
</trkpt>
<trkpt lat="32.288668" lon="-111.120915">
<ele>847.058838</ele>
<time>2002-11-20T23:05:08Z</time>
</trkpt>

Your first one method is one of the way you can get the job done!
String path = "StringPath.xml";
InputStream is = new FileInputStream(new File(ruta));
InputSource inputSrc = new InputSource(is);
XPath xpath = XPathFactory.newInstance().newXPath();
String expression = "//trkpt";
NodeList nodes = (NodeList)xpath.evaluate(expression, inputSrc, XPathConstants.NODESET);
for (int i=0; i < nodes.getLength(); i++){
NamedNodeMap node = nodes.item(i).getAttributes();
System.out.println(node.toString());
}
When I try the code with the xml above, I get 3 item on terminal

Encoding issue on Kit Kat / Android when saving and reading a webview

I have noticed that for Android 4.4 handsets, saving a webview with:
webview.saveWebArchive(name);
and reading it after with WebArchiveReader WebArchiveReader (see code below) throws an Encoding Exception:
11-08 15:10:31.976: W/System.err(2240): org.xml.sax.SAXParseException: Unexpected end of document
11-08 15:10:31.976: W/System.err(2240): at org.apache.harmony.xml.parsers.DocumentBuilderImpl.parse(DocumentBuilderImpl.java:125)
The method used to read the stored XML file worked perfectly fine until 4.3 and it is (NOTE: I tried to parse it in two different ways):
public boolean readWebArchive(InputStream is) {
DocumentBuilderFactory builderFactory =
DocumentBuilderFactory.newInstance();
DocumentBuilder builder = null;
myDoc = null;
try {
builder = builderFactory.newDocumentBuilder();
} catch (ParserConfigurationException e) {
e.printStackTrace();
}
try {
//New attempt
InputSource input = new InputSource(is);
input.setEncoding("UTF-8");
myDoc = builder.parse(input);
//This used to be the way it used to work for
//Android 4.3 and below without trouble
//myDoc = builder.parse(is);
NodeList nl = myDoc.getElementsByTagName("url");
for (int i = 0; i < nl.getLength(); i++) {
Node nd = nl.item(i);
if(nd instanceof Element) {
Element el = (Element) nd;
// siblings of el (url) are: mimeType, textEncoding, frameName, data
NodeList nodes = el.getChildNodes();
for (int j = 0; j < nodes.getLength(); j++) {
Node node = nodes.item(j);
if (node instanceof Text) {
String dt = ((Text)node).getData();
byte[] b = Base64.decode(dt, Base64.DEFAULT);
dt = new String(b);
urlList.add(dt);
urlNodes.add((Element) el.getParentNode());
}
}
}
}
} catch (SAXParseException se){
//Some problems parsing the saved XML file
se.printStackTrace();
myDoc = null;
} catch (Exception e) {
e.printStackTrace();
myDoc = null;
}
return myDoc != null;
}
I've played a bit with the way the buider is invoked. Instead of giving it a FileInputStream, I first create an InputSource as you can see to force a given encoding. However, I had no success. By not including the InputSource, the exception was instead:
org.xml.SAXParseException: Unexpected token
I've read in previous posts that this may be an encoding issue (e.g. android-utf-8-file-parsing) but none of the proposed solutions worked for me.
Does anyone else have the same issue or does anyone know what has changed on Kit Kat, and if so, how could it be avoided?
Many thanks in advance

My WebArchiveReader code is not needed under Android 4.4 KitKat and newer to read back a saved web archive. If you save your page with webview.saveWebArchive(name); method on KitKat, you get an MHTML formatted file, as "#Dragon warrior" indicates above. To read this file back into webview, just use:
webView.loadUrl("file:///my_folder/mySavedPage.mht");
Just make sure to give your file the .mht or .mhtml extension, so that WebView recognizes its contents. Otherwise it may just display the MHTML code in text format.
Greg

I have the exactly same problem as you do.
Apparently, Android 4.4 WebView saves web archives as MHTML. Therefore, you can't use WebArchiveReader anymore.
You might want to parse MHTML files with some other 3rd party lib. Good luck!

Error parsing xml in android

So im trying to parse and xml file in android. Bellow is a link to the file and my code. I'm trying to get the current temp stored as "temp_f" in the "current_conditions" element. But every time i run it i get this error, 09-15 20:26:47.359: DEBUG/ErOr(17663): java.lang.ClassCastException: org.apache.harmony.xml.dom.ElementImpl
http://www.google.com/ig/api?weather=10598
DocumentBuilderFactory factory1 = DocumentBuilderFactory.newInstance();
factory1.setNamespaceAware(true); // never forget this!
InputSource source = new InputSource(new StringReader(xmltemp));
Document doc = factory1.newDocumentBuilder().parse(source);
String newstring = "" + ((DocumentBuilderFactory) ((Document) doc.getDocumentElement().
getElementsByTagName("current_conditions").item(0)).
getElementsByTagName("temp_f").item(0)).
getAttribute("data");

Have a look at the Java XPath API -- that should be much nicer than traversing the DOM to find your data:
URL url = new URL("http://www.google.com/ig/api?weather=10598");
InputSource xml = new InputSource(url.openStream());
XPath xpath = XPathFactory.newInstance().newXPath();
String data = xpath.evaluate("//current_conditions/temp_f/#data", xml);
As for the original question:
First put every statement of your extraction code on a line of its own, this will help you a lot with finding the problems (and line numbers in stacktrace will be a lot more precise):
Element docElem = doc.getDocumentElement();
Document curr_cond = (Document) /*1*/ docElem.getElementsByTagName("current_conditions").item(0);
DocumentBuilderFactory temp_f = (DocumentBuilderFactory) /*2*/ curr_cond.getElementsByTagName("temp_f").item(0);
String newstring = "" + temp_f.getAttribute("data");
At /*1*/ you try to cast a org.w3.dom.Node into an org.w3.dom.Document -- but not every Node is a Document, as can be seen by the ClassCastException here: The returned Node is actually an instance of the org.w3.dom.Element interface, more precisely an instance of class of org.apache.harmony.xml.dom.ElementImpl (part of the Apache Harmony XML parser implementation).
So let's remove the cast and change the declared type of curr_cond to Node:
Element docElem = doc.getDocumentElement();
Node curr_cond = docElem.getElementsByTagName("current_conditions").item(0);
DocumentBuilderFactory temp_f = (DocumentBuilderFactory) /*2*/ curr_cond.getElementsByTagName("temp_f").item(0);
String newstring = "" + temp_f.getAttribute("data");
Now a second problem becomes obvious at /*2*/: The Node interface does not specify a getElementsByTagName() method, that's probably why you did try to cast to Document above. This won't compile and there is no way to get it to.
Why you cast the result to DocumentBuilderFactory is beyond me. Yes, there is a getAttribute() method but both the class name and method javadoc should have made clear that it's definitely not doing want you want.
So my above recommendation holds: Please use XPath, it's the better tool for this task :)
There actually is a way to extract the data using only DOM for your first task (current temperature). It relies on the fact that the temp_f element is unique and is a lot more verbose than the above XPath expression, though:
Element docElem = doc.getDocumentElement();
Node temp_f = docElem.getElementsByTagName("temp_f").item(0);
NamedNodeMap attributes = temp_f.getAttributes();
Node dataAttr = attributes.getNamedItem("data");
String data = dataAttr.getNodeValue();

How to modify XML node value?

I am new developer in java application. I would like to modify an XML file node value. I have used an xml file for modify as follows
<staff id="2">
<firstname>yong</firstname>
<lastname>mook kim</lastname>
<nickname>mkyong</nickname>
<salary>2000000</salary>
<age>28</age>
</staff>
in above xml I would like to change salary value as 345375. For this modification I have written code as follows
try{
DocumentBuilderFactory docFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder docBuilder = docFactory.newDocumentBuilder();
Document doc = docBuilder.parse(new File("/sdcard/myxml.xml"));
//Get the staff element by tag name directly
Node nodes = doc.getElementsByTagName("staff").item(0);
//loop the staff child node
NodeList list = nodes.getChildNodes();
for (int i =0; i<list.getLength();i++){
Node node = list.item(i);
//get the salary element, and update the value
if("salary".equals(node.getNodeName())){
node.setNodeValue("345375");
}
}
}
catch (Exception e) {
e.printStackTrace();
}
if I use this way that value not modifying salary.
How can I modify an XML node value?

First you have to realize that node.setValue() is modifying the representation that is stored in memory. Knowing that, then you just need to figure out how to write that output to disk. See this, for an example.

node.Text = "Enter your value here"; //This will work

parsing does not working in android

I am parsing a xml from an url.The url is has mobile IMEI no and searchstring based on my application. i put my xml parsing code in android project it does not work. but if i run as separate java program it is working. please help me.
Log.e("rsport-", "function1");
try{
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
factory.setIgnoringComments(true);
factory.setCoalescing(true); // Convert CDATA to Text nodes
factory.setNamespaceAware(false); // No namespaces: this is default
factory.setValidating(false); // Don't validate DTD: also default
DocumentBuilder parser = factory.newDocumentBuilder();
Log.e("rsport-", "function2");
Document document = parser.parse("http://demo.greatinnovus.com/restingspot/search?userid=xxxxxxxxxxxxxxxx&firstname=a&lastname=a");
Log.e("rsport-","function3");
NodeList sections = document.getElementsByTagName("Searchdata");
int numSections = sections.getLength();
for (int i = 0; i < numSections; i++)
{
Element section = (Element) sections.item(i);
if(section.hasChildNodes()==true){
NodeList section1=section.getChildNodes();
for(int j=0;j<section1.getLength();j++){
if(section1.item(j).hasChildNodes()==true) {
for(int k=0;k<section1.item(j).getChildNodes().getLength();k++)
xmlvalue=String.valueOf(section1.item(j).getChildNodes().item(k).getNodeValue()).trim();
arl.add(xmlvalue);
}
}
}
}
}
}
catch(Exception e){}
System.out.println("id"+id+" searchdatacount"+searchdatacount);
System.out.println("---------");
ListIterator<String> litr = arl.listIterator();
while (litr.hasNext()) {
String element = litr.next();
Log.e("rsport-", "elememt");
}
after the Log.e("rsport-", "function2"); does not work.

Refer my blog, i had gave Detailed explanation, http://sankarganesh-info-exchange.blogspot.com/2011/04/parsing-data-from-internet-and-creating.html, and make sure , that you had add the Internet permission in your Manifest file.
If you had gone through Myblog, then you will able to notice that you did the following line as wrong
Document document = parser.parse("http://demo.greatinnovus.com/restingspot/search?userid=xxxxxxxxxxxxxxxx&firstname=a&lastname=a");
use like this
URL url =new URL("http://demo.greatinnovus.com/restingspot/search?userid=xxxxxxxxxxxxxxxx&firstname=a&lastname=a");
Document document= parser.parse(new InputSource(url.openStream()));