Develop Reference

Getting null values from XPath query

I have this xml file:
<?xml version="1.0" encoding="UTF-8"?>
<iet:aw-data xmlns:iet="http://care.aw.com/IET/2007/12" class="com.aw.care.bean.resource.MessageResource">
<iet:metadata filter=""/>
<iet:message-resource>
<iet:message>some message 1</iet:message>
<iet:customer id="1"/>
<iet:code>edi.claimfilingindicator.11</iet:code>
<iet:locale>iw_IL</iet:locale>
</iet:message-resource>
<iet:message-resource>
<iet:message>some message 2</iet:message>
<iet:customer id="1"/>
<iet:code>edi.claimfilingindicator.12</iet:code>
<iet:locale>iw_IL</iet:locale>
</iet:message-resource>
.
.
.
.
</iet:aw-data>
Using this code below i'm getting over the data and finding what I need.
try {
FileInputStream fileIS = new FileInputStream(new File("resources\\bootstrap\\content\\MessageResources_iw_IL\\MessageResource_iw_IL.ctdata.xml"));
DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
builderFactory.setNamespaceAware(true); // never forget this!
DocumentBuilder builder = builderFactory.newDocumentBuilder();
Document xmlDocument = builder.parse(fileIS);
XPath xPath = XPathFactory.newInstance().newXPath();
String query = "//*[local-name()='message-resource']//*[local-name()='code'][contains(text(), 'account')]";
NodeList nodeList = (NodeList) xPath.compile(query).evaluate(xmlDocument, XPathConstants.NODESET);
System.out.println("size= " + nodeList.getLength());
for (int i = 0; i < nodeList.getLength(); i++) {
System.out.println(nodeList.item(i).getNodeValue());
}
}
catch (Exception e){
e.printStackTrace();
}
The issue is that i'm getting only null values while printing in the for loop, any idea why it's happened?
The code needs to return a list of nodes which have a code and message fields that contains a given parameters (same as like SQL query with two parameters with operator of AND between them)

Check the documentation:
https://docs.oracle.com/javase/7/docs/api/org/w3c/dom/Node.html
getNodeValue() applied to an element node returns null.
Use getTextContent().
Alternatively, if you find DOM too frustrating, switch to one of the better tree models like JDOM2 or XOM.
Also, if you used an XPath 2.0 engine like Saxon, it would (a) simplify your expression to
//*:message-resource//*:code][contains(text(), 'account')]
and (b) allow you to return a sequence of strings from the XPath expression, rather than a sequence of nodes, so you wouldn't have to mess around with nodelists.
Another point: I suspect that the predicate [contains(text(), 'account')] should really be [.='account']. I'm not sure of that, but using text() instead of ".", and using contains() instead of "=", are both common mistakes.

Access data in xml as string

I am receiving a xml in string format. Is there any library to search for elements in the string?
<Version value="0"/>
<IssueDate>2017-12-15</IssueDate>
<Locale>en_US</Locale>
<RecipientAddress>
<Category>Primary</Category>
<SubCategory>0</SubCategory>
<Name>Vitsi</Name>
<Attention>Stowell Group Llc.</Attention>
<AddressLine1>511 6th St</AddressLine1>
<City>Lake Oswego</City>
<Country>United States</Country>
<PresentationValue>Lake Oswego OR 97034-2903</PresentationValue>
<State>OR</State>
<ZIPCode>97034</ZIPCode>
<ZIP4>2903</ZIP4>
</RecipientAddress>
<RecipientAddress>
<Category>Additional</Category>
<SubCategory>1</SubCategory>
<Name>Vitsi</Name>
<AddressLine1>Po Box 957</AddressLine1>
<City>Lake Oswego</City>
<Country>United States</Country>
<PresentationValue>Lake Oswego OR 97034-0104</PresentationValue>
<State>OR</State>
<ZIPCode>97034</ZIPCode>
<ZIP4>0104</ZIP4>
</RecipientAddress>
<SenderName>TMO</SenderName>
<SenderId>IL</SenderId>
<SenderAddress>
<Name>T-mobile</Name>
<AddressLine1>Po Box 790047</AddressLine1>
<City>St. Louis</City>
<PresentationValue>ST. LOUIS MO 63179-0047</PresentationValue>
<State>MO</State>
<ZIPCode>63179</ZIPCode>
.
.
.
.
I want to access the element RecipientAddress, which is a list. Is there any library to do that? Please note that what I receive is a string. It is an invoice and there will be many to process, so performance is important

Following options are available:
Convert xml string to java objects using JAXB.
Use .indexOf() in string method to retrieve specific parts of xml.
Use regular expression to retrieve specific parts of xml.
SAX/DOM/STAX parser for parsing and extraction from xml.
Xpath for fetching the specific values from xml.

You could use XPATH. Java has inbuilt support for XML querying without any thirdparty library,
Code piece would be,
String xmlInputStr = "<YOUR_XML_STRING_INPUT>"
String xpathExpressionStr = "<XPATH_EXPRESSION_STRING>"
DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
DocumentBuilder builder = factory.newDocumentBuilder();
Document doc = builder.parse(xmlInputStr);
XPathFactory xPathfactory = XPathFactory.newInstance();
XPath xpath = xPathfactory.newXPath();
XPathExpression expr = xpath.compile(xpathExpressionStr);
You can write your own expression string for querying. Typical example
"/RecipientAddress/Category"
Evaluate your xml against expression to retrieve list of nodes.
NodeList nodes = (NodeList) expr.evaluate(doc, XPathConstants.NODESET);
And iterate over nodes,
for (int i = 0; i < nodes.getLength(); i++) {
Node nNode = nodes.item(i);
...
}

There lot of pre-implemented api is available to convert xml to java object.
please look at that the xerces from Apache.
If you want extract only specified value the put whole in to string and use indexOf("string")

Why getting null node value while parsing XML

While parsing the below XML .First url-malformed-exception was coming while parsing so in the code instead of giving the xml String i used this code
Document doc=dBuilder.parse(newInputSource(newByteArrayInputStream(xmlResponse.getBytes("utf-8"))));
according to this link
java.net.MalformedURLException: no protocol
now i am getting the node value as null .How can i overcome this .In the code in for loop i have mentioned where the null value for node is coming
i am using following code:
try {
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(new InputSource(new ByteArrayInputStream(xmlResponse.getBytes("utf-8"))));
//read this - https://stackoverflow.com/questions/13786607/normalization-in-dom-parsing-with-java-how-does-it-work
doc.getDocumentElement().normalize();
System.out.println("Root element :" + doc.getDocumentElement().getNodeName());
XPath xPath = XPathFactory.newInstance().newXPath()
String expression = "/GetMatchingProductForIdResponse/GetMatchingProductForIdResult/Products/Product"
System.out.println(expression)
NodeList nodeList = (NodeList) xPath.compile(expression).evaluate(doc, XPathConstants.NODESET)
System.out.println("the size will be of the node list ${nodeList.getLength()}");
for (int i = 0; i < nodeList.getLength(); i++) {
System.out.println(nodeList.item(i).getNodeValue()+"the value coming will be "); // here i am getting value null for each node
}
} catch (Exception e) {
e.printStackTrace(System.out);
}
to parse the XML:
<?xml version="1.0"?>
<GetMatchingProductForIdResponse xmlns="http://mws.amazonservices.com/schema/Products/2011-10-01">
<GetMatchingProductForIdResult Id="H5-9OSH-9NZ7" IdType="SellerSKU" status="Success">
<Products xmlns="http://mws.amazonservices.com/schema/Products/2011-10-01" xmlns:ns2="http://mws.amazonservices.com/schema/Products/2011-10-01/default.xsd">
<Product>
<Identifiers>
<MarketplaceASIN>
<MarketplaceId>ATVPDKIKX0DER</MarketplaceId>
<ASIN>B004FQLAH2</ASIN>
</MarketplaceASIN>
</Identifiers>
<AttributeSets>
<ns2:ItemAttributes xml:lang="en-US">
<ns2:Binding>Office Product</ns2:Binding>
<ns2:Brand>Konica-Minolta</ns2:Brand>
<ns2:Color>Y</ns2:Color>
<ns2:CPUSpeed Units="MHz">200</ns2:CPUSpeed>
<ns2:Department>Printers</ns2:Department>
<ns2:Feature>Amp Up your Output - The magicolor 3730DN business color laser printer outputs at speeds up to 25 ppm in both color and B&W which means you can keep up in just about any business environment.</ns2:Feature>
<ns2:Feature>Unparalleled Image Quality - High resolution 2400 (equivalent) x 600 dpi printing for great color and clarity in both images and text.</ns2:Feature>
<ns2:Feature>Happy Planet, Outstanding Printing - Simitri HD Toner with Biomass allows for outstanding printing with the environment in mind.</ns2:Feature>
<ns2:Feature>Connect quicker - Why wait? Standard Ethernet and high-speed USB 2.0 gets you connected faster than ever before.Specifications</ns2:Feature>
<ns2:Feature>Type - Full-Color Laser Printer</ns2:Feature>
<ns2:ItemDimensions>
<ns2:Height Units="inches">13.62</ns2:Height>
<ns2:Length Units="inches">20.47</ns2:Length>
<ns2:Width Units="inches">16.50</ns2:Width>
<ns2:Weight Units="pounds">56.22</ns2:Weight>
</ns2:ItemDimensions>
<ns2:IsAutographed>false</ns2:IsAutographed>
<ns2:IsMemorabilia>false</ns2:IsMemorabilia>
<ns2:Label>Konica</ns2:Label>
<ns2:ListPrice>
<ns2:Amount>449.00</ns2:Amount>
<ns2:CurrencyCode>USD</ns2:CurrencyCode>
</ns2:ListPrice>
<ns2:Manufacturer>Konica</ns2:Manufacturer>
<ns2:Model>A0VD017</ns2:Model>
<ns2:NumberOfItems>1</ns2:NumberOfItems>
<ns2:OperatingSystem>Windows XP, Vista, 7</ns2:OperatingSystem>
<ns2:OperatingSystem>Mac X 10.2.8, 10.6+</ns2:OperatingSystem>
<ns2:PackageDimensions>
<ns2:Height Units="inches">19.00</ns2:Height>
<ns2:Length Units="inches">24.20</ns2:Length>
<ns2:Width Units="inches">22.00</ns2:Width>
<ns2:Weight Units="pounds">65.30</ns2:Weight>
</ns2:PackageDimensions>
<ns2:PackageQuantity>1</ns2:PackageQuantity>
<ns2:PartNumber>A0VD017</ns2:PartNumber>
<ns2:ProductGroup>CE</ns2:ProductGroup>
<ns2:ProductTypeName>PRINTER</ns2:ProductTypeName>
<ns2:Publisher>Konica</ns2:Publisher>
<ns2:SmallImage>
<ns2:URL>http://ecx.images-amazon.com/images/I/21qN3BU-BHL._SL75_.jpg</ns2:URL>
<ns2:Height Units="pixels">75</ns2:Height>
<ns2:Width Units="pixels">75</ns2:Width>
</ns2:SmallImage>
<ns2:Studio>Konica</ns2:Studio>
<ns2:Title>Konica Minolta Magicolor 3730DN Color Laser Printer 24PPM 2400X600DPI ENET USB 2.0</ns2:Title>
</ns2:ItemAttributes>
</AttributeSets>
<Relationships/>
<SalesRankings/>
</Product>
</Products>
</GetMatchingProductForIdResult>
<ResponseMetadata>
<RequestId>0b508338-3afe-4178-adc4-60c9c8448987</RequestId>
</ResponseMetadata>
</GetMatchingProductForIdResponse>

The getNodeValue method in the DOM is defined to always return null for element nodes (see the table at the top of the JavaDoc page for org.w3c.dom.Node for details). If you want the text inside the element then you should use getTextContent() instead.
You've added a second question in a comment to this answer asking how you can use an XPath to search for nodes that have a namespace prefix such as ns2:. The way XPath 1.0 handles namespaces is that unprefixed names always refer to nodes that are not in a namespace, and if you want to reference namespaced nodes then you have to provide a binding of namespace URIs to prefixes (which in javax.xml.xpath is the job of a NamespaceContext) and then use those prefixes in the expressions. The prefixes you use in the expression need not be the same ones as the original document used, as long as they bind to the right URIs.
Thus the original XPath you were using:
/GetMatchingProductForIdResponse/GetMatchingProductForIdResult/Products/Product
should not actually have matched anything, because the GetMatchingProductForIdResponse etc. elements in your document are in a namespace, but you got away with it because DocumentBuilderFactory is by default not namespace aware. The correct thing to do here is to use a namespace-aware parser, and provide a suitable namespace context to the XPath engine. There's no default implementation of NamespaceContext available in the core Java library, unfortunately, but Spring provides a convenient SimpleNamespaceContext implementation you can use if you don't want to roll your own.
DocumentBuilderFactory dbFactory = DocumentBuilderFactory.newInstance();
dbFactory.setNamespaceAware(true); // parse with namespaces
DocumentBuilder dBuilder = dbFactory.newDocumentBuilder();
Document doc = dBuilder.parse(new InputSource(new ByteArrayInputStream(xmlResponse.getBytes("utf-8"))));
doc.getDocumentElement().normalize();
XPath xPath = XPathFactory.newInstance().newXPath();
SimpleNamespaceContext nsCtx = new SimpleNamespaceContext();
xPath.setNamespaceContext(nsCtx);
nsCtx.bindNamespaceUri("prod", "http://mws.amazonservices.com/schema/Products/2011-10-01");
nsCtx.bindNamespaceUri("ns2", "http://mws.amazonservices.com/schema/Products/2011-10-01/default.xsd");
String expression = "/prod:GetMatchingProductForIdResponse/prod:GetMatchingProductForIdResult/prod:Products/prod:Product‌​/prod:AttributeSets/ns2:ItemAttributes/ns2:Binding";
// ...

Querying JAXP XPath failing to find node on second call in WebSphere (JUnit works fine)

I'm checking for an element with an xml element, and will be defaulting a value if not present.
This is coming in from a web service call into JAXWS on Websphere 7 as a org.apache.xerces.dom.ElementNSImpl.
// instantiate xpath
XPathFactory xPathFactory = XPathFactory.newInstance();
XPath xPath = xPathFactory.newXPath();
xPath.setNamespaceContext(new NamespaceContext() {
public String getNamespaceURI(String prefix) {
if ("ns".equals(prefix))
return PROVIDER_NAMESPACE;
else
return XMLConstants.NULL_NS_URI;
}
public String getPrefix(String uri) {
return null; // n/a
}
public Iterator<?> getPrefixes(String uri) {
return null; // n/a
}
});
// Check if date is populated
XPathExpression declarationDateXpath = xPath.compile("//ns:Provider/ns:DeclarationDate");
Node dateNode = (Node) providerDateXpath.evaluate(node, XPathConstants.NODE);
if (dateNode == null) {
// if not there, add the node
Document doc = node.getOwnerDocument();
dateNode = doc.createElementNS(PROVIDER_NAMESPACE, "DeclarationDate");
XPathExpression providerXPath = xPath.compile("//ns:Provider");
Node providerNode = (Node) providerXPath.evaluate(node, XPathConstants.NODE);
providerNode.appendChild(dateNode);
}
// Check value & set default if necessary
if (dateNode.getTextContent() == null || "".equals(dateNode.getTextContent())) {
// date not set, defaulting to today
dateNode.setTextContent(today);
}
As you can see I'm instantiating everything as much as I can each call.
The first web service call, it works returning the nodes. The second web service call, it returns null for both xpaths.
According to the javadoc "XPath[and XPathExpression] [objects are] not thread-safe and not reentrant.
Any ideas?

Well ok. I've figured it out I've made it work.
It was the xpath. Well, to be precise, it was the xpath the second time round.
I shortened the xpath from "//ns:Provider/ns:DeclarationDate" (where ns:Provider is the root) to "//ns:DeclarationDate".
There will be a defect somewhere in the WebSphere 7 implementation of JAXP that is causing this, but it's not possible/worthwhile to investigate further.
I hope this helps someone in the future...

How to program some XPath functions using Java Design Patterns

I need your help and your experience to realize the best java code using Design Patterns.
I must write some custom XPath functions that can:
Load a DOM document (I can use a mock object);
Check the validity of an user XPath expression;
Find and return the DOM node that satisfy the user expression.
I must evaluate only absolute expressions ( /... ) that can contain the path expression " .. " and predicates, embedded in square brackets, regarding attributes or leaf nodes, for examples:
/com/university/student/../exam
/com/university/exam[#tt = 'poo']/vote
/com/university/student/number[. = '1234']
I'll use the Composite pattern for the first step, the Chain of Resonsibility for the second step and a Visitor for the third step but I am not sure that this can be the best way to do this.
Can Chain of Resonsibility be usefull to check the validity?
All suggestions are welcome, thank you in advance for any help you can provide.

Isn't it a bit ... overcomplicated?
Create a DOM object for some XML input
Compile the user input - XPath will complain if it is not valid (XPathExpressionException)
Evalute the expression with the DOM object
Sample:
// #1 load document
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
dbf.setValidating(false);
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(file);
// #2 - validate expression
XPathFactory factory = XPathFactory.newInstance();
XPath xpath = factory.newXPath();
XPathExpression expr = null;
try {
XPathExpression expr = xpath.compile(getExpression());
} catch (XPathExpressionException e) {
// ... handle & return <- invalid expression
}
// #3 evaluate expression
String result = expr.evaluate(doc);