Instances of this interface are used to keep the list of ClassLoaders registered in an MBean Server. They provide the necessary methods to load classes using the registered ClassLoaders.
The first ClassLoader in a ClassLoaderRepository
is
always the MBean Server's own ClassLoader.
When an MBean is registered in an MBean Server, if it is of a
subclass of ClassLoader
and if it does not
implement the interface PrivateClassLoader
, it is added to
the end of the MBean Server's ClassLoaderRepository
.
If it is subsequently unregistered from the MBean Server, it is
removed from the ClassLoaderRepository
.
The order of MBeans in the ClassLoaderRepository
is
significant. For any two MBeans X and Y in the
ClassLoaderRepository
, X must appear before
Y if the registration of X was completed before
the registration of Y started. If X and
Y were registered concurrently, their order is
indeterminate. The registration of an MBean corresponds to the
call to MBeanServer.registerMBean(java.lang.Object, javax.management.ObjectName)
or one of the MBeanServer
.createMBean
methods.
- Since:
- 1.5
- See Also:
-
Method Summary
Modifier and TypeMethodDescriptionClass
<?> Load the given class name through the list of class loaders.Class
<?> loadClassBefore
(ClassLoader stop, String className) Load the given class name through the list of class loaders, stopping at the given one.Class
<?> loadClassWithout
(ClassLoader exclude, String className) Load the given class name through the list of class loaders, excluding the given one.
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Method Details
-
loadClass
Load the given class name through the list of class loaders. Each ClassLoader in turn from the ClassLoaderRepository is asked to load the class via its
ClassLoader.loadClass(String)
method. If it successfully returns aClass
object, that is the result of this method. If it throws aClassNotFoundException
, the search continues with the next ClassLoader. If it throws another exception, the exception is propagated from this method. If the end of the list is reached, aClassNotFoundException
is thrown.- Parameters:
className
- The name of the class to be loaded.- Returns:
- the loaded class.
- Throws:
ClassNotFoundException
- The specified class could not be found.
-
loadClassWithout
Load the given class name through the list of class loaders, excluding the given one. Each ClassLoader in turn from the ClassLoaderRepository, except
exclude
, is asked to load the class via itsClassLoader.loadClass(String)
method. If it successfully returns aClass
object, that is the result of this method. If it throws aClassNotFoundException
, the search continues with the next ClassLoader. If it throws another exception, the exception is propagated from this method. If the end of the list is reached, aClassNotFoundException
is thrown.Be aware that if a ClassLoader in the ClassLoaderRepository calls this method from its
loadClass
method, it exposes itself to a deadlock if another ClassLoader in the ClassLoaderRepository does the same thing at the same time. TheloadClassBefore(java.lang.ClassLoader, java.lang.String)
method is recommended to avoid the risk of deadlock.- Parameters:
exclude
- The class loader to be excluded. May be null, in which case this method is equivalent toloadClass(className)
.className
- The name of the class to be loaded.- Returns:
- the loaded class.
- Throws:
ClassNotFoundException
- The specified class could not be found.
-
loadClassBefore
Load the given class name through the list of class loaders, stopping at the given one. Each ClassLoader in turn from the ClassLoaderRepository is asked to load the class via its
ClassLoader.loadClass(String)
method. If it successfully returns aClass
object, that is the result of this method. If it throws aClassNotFoundException
, the search continues with the next ClassLoader. If it throws another exception, the exception is propagated from this method. If the search reachesstop
or the end of the list, aClassNotFoundException
is thrown.Typically this method is called from the
loadClass
method ofstop
, to consult loaders that appear before it in theClassLoaderRepository
. By stopping the search as soon asstop
is reached, a potential deadlock with concurrent class loading is avoided.- Parameters:
stop
- The class loader at which to stop. May be null, in which case this method is equivalent toloadClass(className)
.className
- The name of the class to be loaded.- Returns:
- the loaded class.
- Throws:
ClassNotFoundException
- The specified class could not be found.
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