org.apache.aries.component.dsl

Class CachingServiceReference<T>

java.lang.Object

org.apache.aries.component.dsl.CachingServiceReference<T>

All Implemented Interfaces:

Comparable<CachingServiceReference<T>>

public class CachingServiceReference<T>
extends Object
implements Comparable<CachingServiceReference<T>>

This class is an explicit wrapper around ServiceReference (it DOES NOT implement ServiceReference) and provides methods to access underlying ServiceReference properties and caches them so future access to the same properties return the same values. Property values are cached on demand. Values that have never been queried through the method are not cached. Properties that did not exist when queried will no longer exist even though they were available at a later time in the underlying ServiceReference.

Author:

Carlos Sierra Andrés

Constructor Summary

Constructors

Constructor and Description
CachingServiceReference(org.osgi.framework.ServiceReference<T> serviceReference)

Method Summary

Modifier and Type	Method and Description
int	compareTo(CachingServiceReference<T> o)
boolean	equals(Object o)
String[]	getCachedPropertyKeys()
Object	getProperty(String key) Returns the value associated with a key from the underlying ServiceReference The returned value is then cached and the ServiceReference is never queried again for the same value.
String[]	getPropertyKeys()
org.osgi.framework.ServiceReference<T>	getServiceReference()
int	hashCode()
boolean	isDirty() Checks if any of the cached properties has a different value in the underlying ServiceReference.
boolean	isDirty(String key) Checks if the property is dirty in this instance without caching the value.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

CachingServiceReference

public CachingServiceReference(org.osgi.framework.ServiceReference<T> serviceReference)

Method Detail

compareTo

public int compareTo(CachingServiceReference<T> o)

Specified by:

compareTo in interface Comparable<CachingServiceReference<T>>

getCachedPropertyKeys

public String[] getCachedPropertyKeys()

getProperty

public Object getProperty(String key)

Returns the value associated with a key from the underlying ServiceReference The returned value is then cached and the ServiceReference is never queried again for the same value. Values that are not present in the ServiceReference return null. Values that were present in the moment they were first queried will return the same value even if they disappear from they underlying ServiceReference. Values that were not present when queried the first time will continue to return null even though they exist in future queries.

Parameters:

key - the key of the property to be returned

Returns:

the value associated with that key

getPropertyKeys

public String[] getPropertyKeys()

Returns:

a union of the properties keys already cached by the instance and the property keys available in the underlying ServiceReference. Cached property keys that returned null are not returned here.

getServiceReference

public org.osgi.framework.ServiceReference<T> getServiceReference()

Returns:

The underlying ServiceReference

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object o)

Overrides:

equals in class Object

isDirty

public boolean isDirty()

Checks if any of the cached properties has a different value in the underlying ServiceReference. Only properties that have been accessed through getProperty(String) are checked, so this method can't be used to know whether the underlying ServiceReference han been altered since the creation of the instance.

Returns:

true if any of the cached properties has a different value than the ones held by the underlying ServiceReference

toString

public String toString()

Overrides:

toString in class Object

isDirty

public boolean isDirty(String key)

Checks if the property is dirty in this instance without caching the value. Trying to do the same using getProperty would cache the property which might not be desirable everytime.

Parameters:

key - the key to check for dirtiness

Returns:

true if the cached value for the key is different than the current value in the underlying ServiceReference