XPath issue using JDOM / Jaxen

Question

In my program I am downloading a xml file, shown below.

The task should be very simple to extract just all the Attributes currency and rate.

I am using JDOM and have started as follows:

try {
    // TODO code application logic here
    SAXBuilder builder = new SAXBuilder();
    org.jdom.Document doc = builder.build("test.xml");
    List<?> all = XPath.selectNodes(doc, "/Envelope/Cube/Cube/@currency");
    for(Object o : all) {
        Attribute att = (Attribute) o;
        System.out.println("ausgbabe: " + att);
    }
}

Have tested several paths to get the entries but it is not working.

<?xml version="1.0" encoding="UTF-8"?> 
<gesmes:Envelope xmlns:gesmes="http://www.gesmes.org/xml/2002-08-01" xmlns="http://www.ecb.int/vocabulary/2002-08-01/eurofxref"> 
    <gesmes:subject>Reference rates</gesmes:subject> 
    <gesmes:Sender> 
        <gesmes:name>European Central Bank</gesmes:name> 
    </gesmes:Sender> 
    <Cube> 
        <Cube time='2012-01-17'> 
            <Cube currency='USD' rate='1.2790'/> 
            <Cube currency='JPY' rate='98.20'/> 
            <Cube currency='BGN' rate='1.9558'/> 
            <Cube currency='CZK' rate='25.650'/> 
            <Cube currency='DKK' rate='7.4353'/> 
            <Cube currency='GBP' rate='0.83045'/> 
        </Cube> 
    </Cube> 
</gesmes:Envelope>

javanna · Accepted Answer · 2012-01-21 19:42:45Z

6

You need to bound namespaces to your xpath object. You should create the xpath object like this (I had to add a new Cube entry to your xpath):

XPath xpath = XPath.newInstance("/gesmes:Envelope/root:Cube/root:Cube/root:Cube/@currency");

then add your namespace declarations to it:

xpath.addNamespace("gesmes", "http://www.gesmes.org/xml/2002-08-01");
xpath.addNamespace("root", "http://www.ecb.int/vocabulary/2002-08-01/eurofxref");

In fact, the Envelope element has the "http://www.gesmes.org/xml/2002-08-01" namespace uri, while all the Cube elements have the "http://www.ecb.int/vocabulary/2002-08-01/eurofxref" namespace uri, declared as default namespace. You can use the namespace prefix you want in your xpath, but the uri must match.
Then search through the document like this using the xpath you created:

List<?> all = xpath.selectNodes(doc);

I tested this code with your xml and it produces the following output:

ausgbabe: [Attribute: currency="USD"]
ausgbabe: [Attribute: currency="JPY"]
ausgbabe: [Attribute: currency="BGN"]
ausgbabe: [Attribute: currency="CZK"]
ausgbabe: [Attribute: currency="DKK"]
ausgbabe: [Attribute: currency="GBP"]

edited Jan 21, 2012 at 19:42

answered Jan 19, 2012 at 9:42

javanna

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5 Comments

Alanmars Over a year ago

In actual, it doesn't work after changing the code in your way.

javanna Over a year ago

Well, I tried this code with your xml and it works. I added the output to my answer. Could you please check if you copied all three fragments inside your code?

Alanmars Over a year ago

Yes, it works. the problem results from the default namespace. @javanna

javanna Over a year ago

Yes, the default namespace is tricky. I added a little explanation to my answer. So, have you solved?

Alanmars Over a year ago

Thanks for your answer, but the question is not asked by me. @javanna

OrangeDog · Accepted Answer · 2012-01-19 09:42:07Z

1

You have namespaces in your xml that you haven't told the XPath engine about. You need to use a javax.xml.namespace.NamespaceContext. See this article for a full explanation and guide to get it working.

answered Jan 19, 2012 at 9:42

OrangeDog

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