Oracle® Coherence Java API Reference
v3.5.3

E15583-01

com.tangosol.util.transformer
Class ExtractorEventTransformer

java.lang.Object
  extended by com.tangosol.util.Base
      extended by com.tangosol.util.BitHelper
          extended by com.tangosol.util.ExternalizableHelper
              extended by com.tangosol.util.transformer.ExtractorEventTransformer
All Implemented Interfaces:
ExternalizableLite, PortableObject, MapEventTransformer, java.io.Serializable

public class ExtractorEventTransformer
extends ExternalizableHelper
implements MapEventTransformer, ExternalizableLite, PortableObject

ExtractorEventTransformer is a special purpose MapEventTransformer implementation that transforms emitted events, extracting one or more properties from either the OldValue or the NewValue. This transformation will generally result in the change of the values' data type.

Example: the following code will register a listener to receive events only if the value of the AccountBalance property changes. The transformed event's NewValue will be a List containing the LastTransactionTime and AccountBalance properties. The OldValue will always be null.

    Filter filter = new ValueChangeEventFilter("getAccountBalance");
    ValueExtractor extractor = new MultiExtractor("getLastTransactionTime,getAccountBalance");
    MapEventTransformer transformer = new ExtractorEventTransformer(null, extractor);

    cache.addMapListener(listener, new MapEventTransformerFilter(filter, transformer), false);
 

Since:
Coherence 3.4
Author:
gg 2008.06.01

Constructor Summary
ExtractorEventTransformer()
          No-argument constructor for lite deserialization.
ExtractorEventTransformer(java.lang.String sMethod)
          Construct a ExtractorEventTransformer that transforms MapEvent's values based on the specified method name.
ExtractorEventTransformer(ValueExtractor extractor)
          Construct a ExtractorEventTransformer that transforms MapEvent values based on the specified extractor.
ExtractorEventTransformer(ValueExtractor extractorOld, ValueExtractor extractorNew)
          Construct a ExtractorEventTransformer that transforms MapEvent values based on the specified extractors.
 
Method Summary
 boolean equals(java.lang.Object o)
          Compare the ExtractorEventTransformer with another object to determine equality.
 ValueExtractor getNewValueExtractor()
          Return a ValueExtractor used to transfrom the event's NewValue.
 ValueExtractor getOldValueExtractor()
          Return a ValueExtractor used to transfrom the event's OldValue.
 int hashCode()
          Determine a hash value for the ExtractorEventTransformer object according to the general Object.hashCode() contract.
 void readExternal(java.io.DataInput in)
          Restore the contents of this object by loading the object's state from the passed DataInput object.
 void readExternal(PofReader in)
          Restore the contents of a user type instance by reading its state using the specified PofReader object.
 java.lang.String toString()
          Provide a human-readable representation of this object.
 MapEvent transform(MapEvent event)
          Transform the specified MapEvent using the corresponding extractors.
 void writeExternal(java.io.DataOutput out)
          Save the contents of this object by storing the object's state into the passed DataOutput object.
 void writeExternal(PofWriter out)
          Save the contents of a POF user type instance by writing its state using the specified PofWriter object.
 
Methods inherited from class com.tangosol.util.BitHelper
countBits, countBits, countBits, indexOfLSB, indexOfLSB, indexOfLSB, indexOfMSB, indexOfMSB, indexOfMSB, rotateLeft, rotateLeft, rotateLeft, rotateRight, rotateRight, rotateRight, toBitString, toBitString, toBitString
 

Constructor Detail

ExtractorEventTransformer

public ExtractorEventTransformer()
No-argument constructor for lite deserialization.


ExtractorEventTransformer

public ExtractorEventTransformer(ValueExtractor extractor)
Construct a ExtractorEventTransformer that transforms MapEvent values based on the specified extractor.

Note: The specified extractor will be applied to both old and new values.

Parameters:
extractor - ValueExtractor to extract MapEvent values

ExtractorEventTransformer

public ExtractorEventTransformer(java.lang.String sMethod)
Construct a ExtractorEventTransformer that transforms MapEvent's values based on the specified method name. The name could be a comma-delimited sequence of method names which will result in a MultiExtractor that is based on a corresponding array of ValueExtractor objects; individual array elements will be either ReflectionExtractor or ChainedExtractor objects.

Note: The specified extractor will be applied to both old and new values.

Parameters:
sMethod - the name of the method to invoke via reflection

ExtractorEventTransformer

public ExtractorEventTransformer(ValueExtractor extractorOld,
                                 ValueExtractor extractorNew)
Construct a ExtractorEventTransformer that transforms MapEvent values based on the specified extractors. Passing null indicates that the corresponding values should be skipped completely.

Parameters:
extractorOld - extractor to extract the OldValue property(s)
extractorNew - extractor to extract the NewValue property(s)
Method Detail

getOldValueExtractor

public ValueExtractor getOldValueExtractor()
Return a ValueExtractor used to transfrom the event's OldValue.

Returns:
an extractor from the OldValue

getNewValueExtractor

public ValueExtractor getNewValueExtractor()
Return a ValueExtractor used to transfrom the event's NewValue.

Returns:
an extractor from the NewValue

transform

public MapEvent transform(MapEvent event)
Transform the specified MapEvent using the corresponding extractors.

Specified by:
transform in interface MapEventTransformer
Parameters:
event - MapEvent object to transform
Returns:
a modified MapEvent object that contains extracted values

readExternal

public void readExternal(java.io.DataInput in)
                  throws java.io.IOException
Restore the contents of this object by loading the object's state from the passed DataInput object.

Specified by:
readExternal in interface ExternalizableLite
Parameters:
in - the DataInput stream to read data from in order to restore the state of this object
Throws:
java.io.IOException - if an I/O exception occurs
java.io.NotActiveException - if the object is not in its initial state, and therefore cannot be deserialized into

writeExternal

public void writeExternal(java.io.DataOutput out)
                   throws java.io.IOException
Save the contents of this object by storing the object's state into the passed DataOutput object.

Specified by:
writeExternal in interface ExternalizableLite
Parameters:
out - the DataOutput stream to write the state of this object to
Throws:
java.io.IOException - if an I/O exception occurs

readExternal

public void readExternal(PofReader in)
                  throws java.io.IOException
Restore the contents of a user type instance by reading its state using the specified PofReader object.

Specified by:
readExternal in interface PortableObject
Parameters:
in - the PofReader from which to read the object's state
Throws:
java.io.IOException - if an I/O error occurs

writeExternal

public void writeExternal(PofWriter out)
                   throws java.io.IOException
Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Specified by:
writeExternal in interface PortableObject
Parameters:
out - the PofWriter to which to write the object's state
Throws:
java.io.IOException - if an I/O error occurs

equals

public boolean equals(java.lang.Object o)
Compare the ExtractorEventTransformer with another object to determine equality.

Returns:
true iff this ExtractorEventTransformer and the passed object are equivalent

hashCode

public int hashCode()
Determine a hash value for the ExtractorEventTransformer object according to the general Object.hashCode() contract.

Returns:
an integer hash value for this object

toString

public java.lang.String toString()
Provide a human-readable representation of this object.

Returns:
a String whose contents represent the value of this object

Oracle® Coherence Java API Reference
v3.5.3

E15583-01

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