org.apache.xalan.extensions
Class ExtensionHandlerJavaClass
public class ExtensionHandlerJavaClass
Represents an extension namespace for XPath that handles java classes.
It is recommended that the class URI be of the form:
xalan://fully.qualified.class.name
However, we do not enforce this. If the class name contains a
a /, we only use the part to the right of the rightmost slash.
In addition, we ignore any "class:" prefix.
Provides functions to test a function's existence and call a function.
Also provides functions to test an element's existence and call an
element.
ExtensionHandlerJavaClass(String namespaceUri, String scriptLang, String className) - Construct a new extension namespace handler given all the information
needed.
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ExtensionHandlerJavaClass
public ExtensionHandlerJavaClass(String namespaceUri,
String scriptLang,
String className)
Construct a new extension namespace handler given all the information
needed.
namespaceUri
- the extension namespace URI that I'm implementingscriptLang
- language of code implementing the extensionclassName
- the fully qualified class name of the class
callFunction
public Object callFunction(String funcName,
Vector args,
Object methodKey,
ExpressionContext exprContext)
throws TransformerException
Process a call to a function in the java class represented by
this
ExtensionHandlerJavaClass
.
There are three possible types of calls:
Constructor:
classns:new(arg1, arg2, ...)
Static method:
classns:method(arg1, arg2, ...)
Instance method:
classns:method(obj, arg1, arg2, ...)
We use the following rules to determine the type of call made:
- If the function name is "new", call the best constructor for
class represented by the namespace URI
- If the first argument to the function is of the class specified
in the namespace or is a subclass of that class, look for the best
method of the class specified in the namespace with the specified
arguments. Compare all static and instance methods with the correct
method name. For static methods, use all arguments in the compare.
For instance methods, use all arguments after the first.
- Otherwise, select the best static or instance method matching
all of the arguments. If the best method is an instance method,
call the function using a default object, creating it if needed.
- callFunction in interface ExtensionHandler
funcName
- Function name.args
- The arguments of the function call.methodKey
- A key that uniquely identifies this class and method call.exprContext
- The context in which this expression is being executed.
- the return value of the function evaluation.
callFunction
public Object callFunction(FuncExtFunction extFunction,
Vector args,
ExpressionContext exprContext)
throws TransformerException
Process a call to an XPath extension function
- callFunction in interface ExtensionHandler
extFunction
- The XPath extension functionargs
- The arguments of the function call.exprContext
- The context in which this expression is being executed.
- the return value of the function evaluation.
isElementAvailable
public boolean isElementAvailable(String element)
Tests whether a certain element name is known within this namespace.
Looks for a method with the appropriate name and signature.
This method examines both static and instance methods.
- isElementAvailable in interface ExtensionHandler
element
- name of the element being tested
- true if its known, false if not.
isFunctionAvailable
public boolean isFunctionAvailable(String function)
Tests whether a certain function name is known within this namespace.
Simply looks for a method with the appropriate name. There is
no information regarding the arguments to the function call or
whether the method implementing the function is a static method or
an instance method.
- isFunctionAvailable in interface ExtensionHandler
function
- name of the function being tested
- true if its known, false if not.
processElement
public void processElement(String localPart,
ElemTemplateElement element,
TransformerImpl transformer,
Stylesheet stylesheetTree,
Object methodKey)
throws TransformerException,
IOException
Process a call to this extension namespace via an element. As a side
effect, the results are sent to the TransformerImpl's result tree.
We invoke the static or instance method in the class represented by
by the namespace URI. If we don't already have an instance of this class,
we create one upon the first call.
- processElement in interface ExtensionHandler
localPart
- Element name's local part.element
- The extension element being processed.transformer
- Handle to TransformerImpl.stylesheetTree
- The compiled stylesheet tree.methodKey
- A key that uniquely identifies this element call.
Copyright B) 2006 Apache XML Project. All Rights Reserved.