Interface ClassLoaderRepository
public interface ClassLoaderRepository
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:
MBeanServerFactory
Method Summary
Modifier and Type | Method | Description |
---|---|---|
Class<?> | loadClass(String className) | 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. |
Method Detail
loadClass
Class<?> loadClass(String className) throws ClassNotFoundException
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 a Class
object, that is the result of this method. If it throws a ClassNotFoundException
, 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, a ClassNotFoundException
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
Class<?> loadClassWithout(ClassLoader exclude, String className) throws ClassNotFoundException
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 its ClassLoader.loadClass(String)
method. If it successfully returns a Class
object, that is the result of this method. If it throws a ClassNotFoundException
, 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, a ClassNotFoundException
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. The loadClassBefore(java.lang.ClassLoader, java.lang.String)
method is recommended to avoid the risk of deadlock.
- Parameters:
-
className
- The name of the class to be loaded. -
exclude
- The class loader to be excluded. May be null, in which case this method is equivalent toloadClass(className)
. - Returns:
- the loaded class.
- Throws:
-
ClassNotFoundException
- The specified class could not be found.
loadClassBefore
Class<?> loadClassBefore(ClassLoader stop, String className) throws ClassNotFoundException
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 a Class
object, that is the result of this method. If it throws a ClassNotFoundException
, the search continues with the next ClassLoader. If it throws another exception, the exception is propagated from this method. If the search reaches stop
or the end of the list, a ClassNotFoundException
is thrown.
Typically this method is called from the loadClass
method of stop
, to consult loaders that appear before it in the ClassLoaderRepository
. By stopping the search as soon as stop
is reached, a potential deadlock with concurrent class loading is avoided.
- Parameters:
-
className
- The name of the class to be loaded. -
stop
- The class loader at which to stop. May be null, in which case this method is equivalent toloadClass(className)
. - Returns:
- the loaded class.
- Throws:
-
ClassNotFoundException
- The specified class could not be found.