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Oracle® Fusion Middleware Java API Reference for Oracle Coherence 12c (12.1.3.0.0) E47890-01 |
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java.lang.Object
com.tangosol.util.Base
com.tangosol.util.BitHelper
com.tangosol.util.ExternalizableHelper
com.tangosol.util.extractor.AbstractExtractor
com.tangosol.util.extractor.KeyExtractor
public class KeyExtractor
The KeyExtractor is a special purpose ValueExtractor implementation that serves as an indicator that a query should be run against the key objects rather than the values. The major difference between the KeyExtractor and a standard ReflectionExtractor
is that when used in various EntryFilter
implementations it forces the evaluation of entry keys rather than entry values.
For example, consider a key object that consists of two properties: "FirstName" and "LastName". To retrieve all keys that have a value of the "LastName" property equal to "Smith", the following query could be used:
ValueExtractor extractor = new KeyExtractor("getLastName"); Set setKeys = cache.keySet(new EqualsFilter(extractor, "Smith"));
As of Coherence 3.5, the same effect can be achieved for subclasses of the AbstractExtractor, for example:
ValueExtractor extractor = new ReflectionExtractor("getLastName", null, AbstractExtractor.KEY); Set setKeys = cache.keySet(new EqualsFilter(extractor, "Smith"));
Note: This class does not function with PofExtractor
and the mechanism described above is recommended.
Field Summary | |
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protected ValueExtractor |
m_extractor The underlying ValueExtractor. |
Fields inherited from class com.tangosol.util.extractor.AbstractExtractor |
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KEY, m_nTarget, VALUE |
Constructor Summary | |
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KeyExtractor() Default constructor (necessary for the ExternalizableLite and PortableObject interfaces). |
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KeyExtractor(java.lang.String sMethod) Construct a KeyExtractor for a specified method name. |
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KeyExtractor(ValueExtractor extractor) Construct a KeyExtractor based on a specified ValueExtractor. |
Method Summary | |
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boolean |
equals(java.lang.Object o) Compare the KeyExtractor with another object to determine equality. |
java.lang.Object |
extract(java.lang.Object oTarget) Extract the value from the passed object. |
ValueExtractor |
getExtractor() Obtain the underlying ValueExtractor. |
int |
hashCode() Determine a hash value for the KeyExtractor 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() Return a human-readable description for this KeyExtractor. |
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.extractor.AbstractExtractor |
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compare, compareEntries, extractFromEntry, extractOriginalFromEntry |
Methods inherited from class com.tangosol.util.BitHelper |
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countBits, countBits, countBits, indexOfLSB, indexOfLSB, indexOfLSB, indexOfMSB, indexOfMSB, indexOfMSB, rotateLeft, rotateLeft, rotateLeft, rotateRight, rotateRight, rotateRight, toBitString, toBitString, toBitString, toBytes, toBytes, toBytes, toBytes, toInt, toInt, toLong, toLong |
Field Detail |
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protected ValueExtractor m_extractor
Constructor Detail |
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public KeyExtractor()
public KeyExtractor(ValueExtractor extractor)
extractor
- the underlying ValueExtractorpublic KeyExtractor(java.lang.String sMethod)
sMethod
- a method name to construct an underlying ReflectionExtractor
for; this parameter can also be a dot-delimited sequence of method names which would result in a KeyExtractor based on the ChainedExtractor
that is based on an array of corresponding ReflectionExtractor objectsMethod Detail |
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public java.lang.Object extract(java.lang.Object oTarget)
extract
in interface ValueExtractor
extract
in class AbstractExtractor
oTarget
- an Object to retrieve the value frompublic ValueExtractor getExtractor()
public boolean equals(java.lang.Object o)
equals
in interface ValueExtractor
equals
in interface java.util.Comparator
o
- the reference object with which to comparepublic int hashCode()
Object.hashCode()
contract.hashCode
in interface ValueExtractor
public java.lang.String toString()
toString
in interface ValueExtractor
public void readExternal(java.io.DataInput in) throws java.io.IOException
readExternal
in interface ExternalizableLite
in
- the DataInput stream to read data from in order to restore the state of this objectjava.io.IOException
- if an I/O exception occursjava.io.NotActiveException
- if the object is not in its initial state, and therefore cannot be deserialized intopublic void writeExternal(java.io.DataOutput out) throws java.io.IOException
writeExternal
in interface ExternalizableLite
out
- the DataOutput stream to write the state of this object tojava.io.IOException
- if an I/O exception occurspublic void readExternal(PofReader in) throws java.io.IOException
readExternal
in interface PortableObject
in
- the PofReader from which to read the object's statejava.io.IOException
- if an I/O error occurspublic void writeExternal(PofWriter out) throws java.io.IOException
writeExternal
in interface PortableObject
out
- the PofWriter to which to write the object's statejava.io.IOException
- if an I/O error occurs
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Oracle® Fusion Middleware Java API Reference for Oracle Coherence 12c (12.1.3.0.0) E47890-01 |
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