Evaluate the compiled XPath expression in the specified context and * return the result as the specified type.
* *See "Evaluation of XPath Expressions" section of JAXP 1.3 spec * for context item evaluation, * variable, function and QName resolution and return type conversion.
* *If returnType is not one of the types defined
* in {@link XPathConstants},
* then an IllegalArgumentException is thrown.
If a null value is provided for
* item, an empty document will be used for the
* context.
* If returnType is null, then a
* NullPointerException is thrown.
Object that is the result of evaluating the
* expression and converting the result to
* returnType.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws IllegalArgumentException If returnType is not one
* of the types defined in {@link XPathConstants}.
* @throws NullPointerException If returnType is
* null.
*/
public Object evaluate(Object item, QName returnType)
throws XPathExpressionException {
//Validating parameters to enforce constraints defined by JAXP spec
if ( returnType == null ) {
//Throwing NullPointerException as defined in spec
String fmsg = XSLMessages.createXPATHMessage(
XPATHErrorResources.ER_ARG_CANNOT_BE_NULL,
new Object[] {"returnType"} );
throw new NullPointerException( fmsg );
}
// Checking if requested returnType is supported. returnType need to be
// defined in XPathConstants
if ( !isSupported ( returnType ) ) {
String fmsg = XSLMessages.createXPATHMessage(
XPATHErrorResources.ER_UNSUPPORTED_RETURN_TYPE,
new Object[] { returnType.toString() } );
throw new IllegalArgumentException ( fmsg );
}
try {
return eval( item, returnType);
} catch ( java.lang.NullPointerException npe ) {
// If VariableResolver returns null Or if we get
// NullPointerException at this stage for some other reason
// then we have to reurn XPathException
throw new XPathExpressionException ( npe );
} catch ( javax.xml.transform.TransformerException te ) {
Throwable nestedException = te.getException();
if ( nestedException instanceof javax.xml.xpath.XPathFunctionException ) {
throw (javax.xml.xpath.XPathFunctionException)nestedException;
} else {
// For any other exceptions we need to throw
// XPathExpressionException ( as per spec )
throw new XPathExpressionException( te);
}
}
}
/**
* Evaluate the compiled XPath expression in the specified context and
* return the result as a String.
This method calls {@link #evaluate(Object item, QName returnType)}
* with a returnType of
* {@link XPathConstants#STRING}.
See "Evaluation of XPath Expressions" section of JAXP 1.3 spec * for context item evaluation, * variable, function and QName resolution and return type conversion.
* *If a null value is provided for
* item, an empty document will be used for the
* context.
*
* @param item The starting context (node or node list, for example).
*
* @return The String that is the result of evaluating the
* expression and converting the result to a
* String.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
*/
public String evaluate(Object item)
throws XPathExpressionException {
return (String)this.evaluate( item, XPathConstants.STRING );
}
static DocumentBuilderFactory dbf = null;
static DocumentBuilder db = null;
static Document d = null;
/**
*
Evaluate the compiled XPath expression in the context of the
* specified InputSource and return the result as the
* specified type.
This method builds a data model for the {@link InputSource} and calls * {@link #evaluate(Object item, QName returnType)} on the resulting * document object.
* *See "Evaluation of XPath Expressions" section of JAXP 1.3 spec * for context item evaluation, * variable, function and QName resolution and return type conversion.
* *If returnType is not one of the types defined in
* {@link XPathConstants},
* then an IllegalArgumentException is thrown.
If source or returnType is null,
* then a NullPointerException is thrown.
InputSource of the document to evaluate
* over.
* @param returnType The desired return type.
*
* @return The Object that is the result of evaluating the
* expression and converting the result to
* returnType.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws IllegalArgumentException If returnType is not one
* of the types defined in {@link XPathConstants}.
* @throws NullPointerException If source or
* returnType is null.
*/
public Object evaluate(InputSource source, QName returnType)
throws XPathExpressionException {
if ( ( source == null ) || ( returnType == null ) ) {
String fmsg = XSLMessages.createXPATHMessage(
XPATHErrorResources.ER_SOURCE_RETURN_TYPE_CANNOT_BE_NULL,
null );
throw new NullPointerException ( fmsg );
}
// Checking if requested returnType is supported. returnType need to be
// defined in XPathConstants
if ( !isSupported ( returnType ) ) {
String fmsg = XSLMessages.createXPATHMessage(
XPATHErrorResources.ER_UNSUPPORTED_RETURN_TYPE,
new Object[] { returnType.toString() } );
throw new IllegalArgumentException ( fmsg );
}
try {
if ( dbf == null ) {
dbf = FactoryImpl.getDOMFactory(useServicesMechanism);
dbf.setNamespaceAware( true );
dbf.setValidating( false );
}
db = dbf.newDocumentBuilder();
Document document = db.parse( source );
return eval( document, returnType );
} catch ( Exception e ) {
throw new XPathExpressionException ( e );
}
}
/**
* Evaluate the compiled XPath expression in the context of the specified InputSource and return the result as a
* String.
This method calls {@link #evaluate(InputSource source, QName returnType)} with a returnType of
* {@link XPathConstants#STRING}.
See "Evaluation of XPath Expressions" section of JAXP 1.3 spec * for context item evaluation, * variable, function and QName resolution and return type conversion.
* *If source is null, then a NullPointerException is thrown.
InputSource of the document to evaluate over.
*
* @return The String that is the result of evaluating the expression and converting the result to a
* String.
*
* @throws XPathExpressionException If the expression cannot be evaluated.
* @throws NullPointerException If source is null.
*/
public String evaluate(InputSource source)
throws XPathExpressionException {
return (String)this.evaluate( source, XPathConstants.STRING );
}
private boolean isSupported( QName returnType ) {
// XPathConstants.STRING
if ( ( returnType.equals( XPathConstants.STRING ) ) ||
( returnType.equals( XPathConstants.NUMBER ) ) ||
( returnType.equals( XPathConstants.BOOLEAN ) ) ||
( returnType.equals( XPathConstants.NODE ) ) ||
( returnType.equals( XPathConstants.NODESET ) ) ) {
return true;
}
return false;
}
private Object getResultAsType( XObject resultObject, QName returnType )
throws javax.xml.transform.TransformerException {
// XPathConstants.STRING
if ( returnType.equals( XPathConstants.STRING ) ) {
return resultObject.str();
}
// XPathConstants.NUMBER
if ( returnType.equals( XPathConstants.NUMBER ) ) {
return new Double ( resultObject.num());
}
// XPathConstants.BOOLEAN
if ( returnType.equals( XPathConstants.BOOLEAN ) ) {
return new Boolean( resultObject.bool());
}
// XPathConstants.NODESET ---ORdered, UNOrdered???
if ( returnType.equals( XPathConstants.NODESET ) ) {
return resultObject.nodelist();
}
// XPathConstants.NODE
if ( returnType.equals( XPathConstants.NODE ) ) {
NodeIterator ni = resultObject.nodeset();
//Return the first node, or null
return ni.nextNode();
}
// If isSupported check is already done then the execution path
// shouldn't come here. Being defensive
String fmsg = XSLMessages.createXPATHMessage(
XPATHErrorResources.ER_UNSUPPORTED_RETURN_TYPE,
new Object[] { returnType.toString()});
throw new IllegalArgumentException ( fmsg );
}
}