What is the difference between localname and qname?

java xml sax
Bob picture Bob · Aug 23, 2011 · Viewed 40.5k times · Source

When using SAX to parse an XML file in Java, what is the difference between the parameters localname and qname in SAX methods such as startElement(String uri, String localName,String qName, Attributes attributes)?

Answer

bdoughan picture bdoughan · Aug 23, 2011

The qualified name includes both the namespace prefix and the local name: att1 and foo:att2.

Sample XML

<root 
    xmlns="http://www.example.com/DEFAULT" 
    att1="Hello" 
    xmlns:foo="http://www.example.com/FOO" 
    foo:att2="World"/>

Java Code:

att1

Attributes without a namespace prefix do not pick up the default namespace. This means while the namespace for the root element is "http://www.example.com/DEFAULT", the namespace for the att1 attribute is "".

int att1Index = attributes.getIndex("", "att1");
attributes.getLocalName(att1Index);  // returns "att1"
attributes.getQName(att1Index);  // returns "att1"
attributes.getURI(att1Index);  // returns ""

att2

int att2Index = attributes.getIndex("http://www.example.com/FOO", "att2");
attributes.getLocalName(att2Index);  // returns "att2"
attributes.getQName(att2Index);  // returns "foo:att2"
attributes.getURI(att2Index);  // returns "http://www.example.com/FOO"

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