javax.management.loading

Interface ClassLoaderRepository

Contents

  • 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 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 to loadClass(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 to loadClass(className).
        Returns:
        the loaded class.
        Throws:
        ClassNotFoundException - The specified class could not be found.

Document created the 11/06/2005, last modified the 04/03/2020
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