com.espertech.esper.event.xml
Class XPathPropertyGetter

java.lang.Object
  com.espertech.esper.event.xml.XPathPropertyGetter

All Implemented Interfaces:

EventPropertyGetter

public class XPathPropertyGetter
extends java.lang.Object
implements EventPropertyGetter

Getter for properties of DOM xml events.

Author:

pablo

Constructor Summary

XPathPropertyGetter(java.lang.String propertyName, java.lang.String expressionText, javax.xml.xpath.XPathExpression xPathExpression, javax.xml.namespace.QName resultType, java.lang.Class optionalCastToType, FragmentFactory fragmentFactory)
Ctor.

Method Summary

java.lang.Object	get(EventBean eventBean) Return the value for the property in the event object specified when the instance was obtained.
java.lang.Object	getFragment(EventBean eventBean) Returns EventBean or array of EventBean for a property name or property expression.
boolean	isExistsProperty(EventBean eventBean) Returns true if the property exists, or false if the type does not have such a property.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

XPathPropertyGetter

public XPathPropertyGetter(java.lang.String propertyName,
                           java.lang.String expressionText,
                           javax.xml.xpath.XPathExpression xPathExpression,
                           javax.xml.namespace.QName resultType,
                           java.lang.Class optionalCastToType,
                           FragmentFactory fragmentFactory)

Ctor.

Parameters:

propertyName - is the name of the event property for which this getter gets values

expressionText - is the property expression itself

xPathExpression - is a compile XPath expression

resultType - is the resulting type

optionalCastToType - if non-null then the return value of the xpath expression is cast to this value

fragmentFactory - for creating fragments, or null in none to be created

Method Detail

get

public java.lang.Object get(EventBean eventBean)
                     throws PropertyAccessException

Description copied from interface: EventPropertyGetter

Return the value for the property in the event object specified when the instance was obtained. Useful for fast access to event properties. Throws a PropertyAccessException if the getter instance doesn't match the EventType it was obtained from, and to indicate other property access problems.

Specified by:

get in interface EventPropertyGetter

Parameters:

eventBean - is the event to get the value of a property from

Returns:

value of property in event

Throws:

PropertyAccessException - to indicate that property access failed

isExistsProperty

public boolean isExistsProperty(EventBean eventBean)

Description copied from interface: EventPropertyGetter

Returns true if the property exists, or false if the type does not have such a property.

Useful for dynamic properties of the syntax "property?" and the dynamic nested/indexed/mapped versions. Dynamic nested properties follow the syntax "property?.nested" which is equivalent to "property?.nested?". If any of the properties in the path of a dynamic nested property return null, the dynamic nested property does not exists and the method returns false.

For non-dynamic properties, this method always returns true since a getter would not be available unless

Specified by:

isExistsProperty in interface EventPropertyGetter

Parameters:

eventBean - is the event to check if the dynamic property exists

Returns:

indictor whether the property exists, always true for non-dynamic (default) properties

getFragment

public java.lang.Object getFragment(EventBean eventBean)

Description copied from interface: EventPropertyGetter

Returns EventBean or array of EventBean for a property name or property expression.

For use with properties whose value is itself an event or whose value can be represented as an event by the underlying event representation.

The EventType of the EventBean instance(s) returned by this method can be determined by EventType.getFragmentType(String). Use EventPropertyDescriptor to obtain a list of properties that return fragments from an event type.

Returns null if the property value is null or the property value cannot be represented as a fragment by the underlying representation.

Specified by:

getFragment in interface EventPropertyGetter

Parameters:

eventBean - is the event to get the fragment value of a property

Returns:

the value of a property as an EventBean or array of EventBean