Guillaume Nodet created KARAF-5757:
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Summary: Improve shell reflection capabilities
Key: KARAF-5757
URL: https://issues.apache.org/jira/browse/KARAF-5757
Project: Karaf
Issue Type: New Feature
Reporter: Guillaume Nodet
Fix For: 4.3.0
Writing karaf scripts can be very tedious when dealing with reflection and
classes.
It needs to be simplified a lot.
Below is a script definining a command to create a service tracker:
{code:java}
create-tracker = {
trackingContext = $1
trackedClass = $2
serviceAdded = $3
serviceRemoved = $4
shellClassLoader = (($.session class) getClassLoader)
arrayClass = ($shellClassLoader loadClass java.lang.reflect.Array)
handler = {
proxy = $1
method = $2
arguments = $3
name = ($method name)
# echo "Invoking $name"
if { $name equals "addingService" } \
then {
ref = ($arrayClass get $arguments 0)
svc = ($.context getService $ref)
$serviceAdded execute $.commandSession [ $svc ]
$svc
} elif { $name equals "removedService" } \
then {
ref = ($arrayClass get $arguments 0)
svc = ($arrayClass get $arguments 1)
$serviceRemoved execute $.commandSession [ $svc ]
$.context ungetService $ref
}
}
# create handler
customizerClass = ($shellClassLoader loadClass
org.osgi.util.tracker.ServiceTrackerCustomizer)
array = ([ $customizerClass ] toArray ($arrayClass newInstance
"java.lang.Class" 1))
proxyClass = ($shellClassLoader loadClass java.lang.reflect.Proxy)
customizer = ($proxyClass newProxyInstance $shellClassLoader $array
$handler)
# create tracker
trackerClass = ($shellClassLoader loadClass
org.osgi.util.tracker.ServiceTracker)
constructor = ($trackerClass constructor
org.osgi.framework.BundleContext java.lang.String
org.osgi.util.tracker.ServiceTrackerCustomizer)
if { "java.lang.Class" equals ($trackedClass class) } \
then {
trackedClass = ($trackedClass name)
}
tracker = ($constructor newInstance $trackingContext $trackedClass
$customizer)
$tracker
}
tracker = (create-tracker $.context "org.osgi.service.cm.ManagedService" { s =
(($1 class) toString); echo "service-added $s" } { s = (($1 class) toString);
echo "service-removed $s" })
$tracker open true
{code}
Also, the Gogo Runtime expander does not support subscripts in java arrays. It
has to be a {{List}}. This should be fixed, see
[https://github.com/apache/felix/blob/trunk/gogo/runtime/src/main/java/org/apache/felix/gogo/runtime/Expander.java#L1483].
Conversion from list to array would be needed too.
In order to be more user-friendly, we need helper methods to define a context
class loader, load classes (the String -> Class conversion needs to leverage
it).
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