Parsing XML Node in Java using XPATH

Question

I just started to try Jaxp13XPathTemplate but I'm a bit confused on parsing the XML.

Here is the sample XML

<fxDataSets> 
<fxDataSet name="NAME_A">
  <link rel="self" href="http://localhost:8080/linkA"/>
  <baseCurrency>EUR</baseCurrency>
  <description>TEST DESCRIPTION A</description>
</fxDataSet>

<fxDataSet name="NAME_B">
  <link rel="self" href="http://localhost:8080/linkB"/>
  <baseCurrency>EUR</baseCurrency>
  <description>TEST DESCRIPTION B</description>
</fxDataSet>
<fxDataSets>  

I'm already able to get NAME_A and NAME_B however I'm not able to get the description for both Node.

Here is what I have come up with.

XPathOperations  xpathTemplate = new Jaxp13XPathTemplate();
    String fxRateURL = "http://localhost:8080/rate/datasets";
    RestTemplate restTemplate = new RestTemplate();
    Source fxRate = restTemplate.getForObject(fxRateURL,Source.class);
    List<Map<String, Object>> currencyList = xpathTemplate.evaluate("//fxDataSet", fxRate , new NodeMapper() {
        public Object mapNode(Node node, int i) throws DOMException 
        {
            Map<String, Object> singleFXMap = new HashMap<String, Object>();
            Element fxDataSet = (Element) node;
            String id    = fxDataSet.getAttribute("name");

            /* This part is not working
            if(fxDataSet.hasChildNodes())
            {
                NodeList nodeList = fxDataSet.getChildNodes();
                int length = nodeList.getLength();

                for(int index=0;i<length;i++)
                {
                    Node childNode = nodeList.item(index);
                    System.out.println("childNode name"+childNode.getLocalName()+":"+childNode.getNodeValue());
                }

            }*/

            return new Object();
        }
    });

Answer 1

try to use dom4j library and it's saxReader.

    InputStream is = FileUtils.class.getResourceAsStream("file.xml");

    SAXReader reader = new SAXReader();
    org.dom4j.Document doc = reader.read(is);
    is.close();
    Element content = doc.getRootElement();  //this will return the root element in your xml file
    List<Element> methodEls = content.elements("element"); // this will retun List of all Elements with name "element" 

Answer 2

Take a look public <T> List<T> evaluate(String expression, Source context, NodeMapper<T> nodeMapper)

• evaluate takes NodeMapper<T> as one of its parameter
• it returns object of type List<T>

But for your given code snippet:

• its passing new NodeMapper() as parameter
• but trying to return List<Map<String, Object>> which is surely violation of the contract of the api.

Probable solution:

I am assuming you wanna return a object of type FxDataSet which wraps <fxDataSet>...</fxDataSet> element. If this is the case,

• pass parameter as new NodeMapper<FxDataSet>() as parameter
• use List<FxDataSet> currencyList = ... as left hand side expression;
• change method return type as public FxDataSet mapNode(Node node, int i) throws DOMException.

Take a look at the documentation also for NodeMapper.

Surely, I have not used Jaxp13XPathTemplate, but this should be common Java concept which helped me to find out what was wrong actually. I wish this solution will work.

Answer 3

If you want to get at the child nodes of the fxDataSet element you should be able to do:

Node descriptionNode= fxDataSet.getElementsByTagName("description").item(0);