Class MultipleParentClassLoader


  • public class MultipleParentClassLoader
    extends InjectionClassLoader

    This ClassLoader is capable of loading classes from multiple parents. This class loader implicitly defines the bootstrap class loader to be its direct parent as it is required for all class loaders. This can be useful when creating a type that inherits a super type and interfaces that are defined by different, non-compatible class loaders.

    Note: Instances of this class loader can have the same class loader as its parent multiple times, either directly or indirectly by multiple parents sharing a common parent class loader. By definition, this implies that the bootstrap class loader is #(direct parents) + 1 times a parent of this class loader. For the ClassLoader.getResources(java.lang.String) method, this means that this class loader might return the same url multiple times by representing the same class loader multiple times.

    Important: This class loader does not support the location of packages from its multiple parents. This breaks package equality when loading classes by either loading them directly via this class loader (e.g. by subclassing) or by loading classes with child class loaders of this class loader.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private java.util.List<? extends java.lang.ClassLoader> parents
      The parents of this class loader in their application order.
    • Constructor Summary

      Constructors 
      Constructor Description
      MultipleParentClassLoader​(java.lang.ClassLoader parent, java.util.List<? extends java.lang.ClassLoader> parents)
      Creates a new class loader with multiple parents.
      MultipleParentClassLoader​(java.lang.ClassLoader parent, java.util.List<? extends java.lang.ClassLoader> parents, boolean sealed)
      Creates a new class loader with multiple parents.
      MultipleParentClassLoader​(java.util.List<? extends java.lang.ClassLoader> parents)
      Creates a new class loader with multiple parents.
    • Method Summary

      All Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      protected java.util.Map<java.lang.String,​java.lang.Class<?>> doDefineClasses​(java.util.Map<java.lang.String,​byte[]> typeDefinitions)
      Defines a group of types to be loaded by this class loader.
      java.net.URL getResource​(java.lang.String name)
      java.util.Enumeration<java.net.URL> getResources​(java.lang.String name)
      protected java.lang.Class<?> loadClass​(java.lang.String name, boolean resolve)
      • Methods inherited from class java.lang.ClassLoader

        clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findClass, findClass, findLibrary, findLoadedClass, findResource, findResource, findResources, findSystemClass, getClassLoadingLock, getDefinedPackage, getDefinedPackages, getName, getPackage, getPackages, getParent, getPlatformClassLoader, getResourceAsStream, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, getUnnamedModule, isRegisteredAsParallelCapable, loadClass, registerAsParallelCapable, resolveClass, resources, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • parents

        private final java.util.List<? extends java.lang.ClassLoader> parents
        The parents of this class loader in their application order.
    • Constructor Detail

      • MultipleParentClassLoader

        public MultipleParentClassLoader​(java.util.List<? extends java.lang.ClassLoader> parents)
        Creates a new class loader with multiple parents.
        Parameters:
        parents - The parents of this class loader in their application order. This list must not contain null, i.e. the bootstrap class loader which is an implicit parent of any class loader.
      • MultipleParentClassLoader

        public MultipleParentClassLoader​(java.lang.ClassLoader parent,
                                         java.util.List<? extends java.lang.ClassLoader> parents)
        Creates a new class loader with multiple parents.
        Parameters:
        parent - An explicit parent in compliance with the class loader API. This explicit parent should only be set if the current platform does not allow creating a class loader that extends the bootstrap loader.
        parents - The parents of this class loader in their application order. This list must not contain null, i.e. the bootstrap class loader which is an implicit parent of any class loader.
      • MultipleParentClassLoader

        public MultipleParentClassLoader​(java.lang.ClassLoader parent,
                                         java.util.List<? extends java.lang.ClassLoader> parents,
                                         boolean sealed)
        Creates a new class loader with multiple parents.
        Parameters:
        parent - An explicit parent in compliance with the class loader API. This explicit parent should only be set if the current platform does not allow creating a class loader that extends the bootstrap loader.
        parents - The parents of this class loader in their application order. This list must not contain null, i.e. the bootstrap class loader which is an implicit parent of any class loader.
        sealed - true if the class loader is sealed for injection of additional classes.
    • Method Detail

      • loadClass

        protected java.lang.Class<?> loadClass​(java.lang.String name,
                                               boolean resolve)
                                        throws java.lang.ClassNotFoundException
        Overrides:
        loadClass in class java.lang.ClassLoader
        Throws:
        java.lang.ClassNotFoundException
      • getResource

        public java.net.URL getResource​(java.lang.String name)
        Overrides:
        getResource in class java.lang.ClassLoader
      • getResources

        public java.util.Enumeration<java.net.URL> getResources​(java.lang.String name)
                                                         throws java.io.IOException
        Overrides:
        getResources in class java.lang.ClassLoader
        Throws:
        java.io.IOException
      • doDefineClasses

        protected java.util.Map<java.lang.String,​java.lang.Class<?>> doDefineClasses​(java.util.Map<java.lang.String,​byte[]> typeDefinitions)
        Description copied from class: InjectionClassLoader
        Defines a group of types to be loaded by this class loader.
        Specified by:
        doDefineClasses in class InjectionClassLoader
        Parameters:
        typeDefinitions - The types binary representations.
        Returns:
        The mapping of defined classes or previously defined classes by their name.