Package org.apache.logging.log4j.util

Class LoaderUtil

java.lang.Object
org.apache.logging.log4j.util.LoaderUtil
@InternalApi public final class LoaderUtil extends Object
Consider this class private. Utility class for ClassLoaders.
Since:
2.0.1
See Also:

  • Field Details

    • IGNORE_TCCL_PROPERTY

      public static final String IGNORE_TCCL_PROPERTY
      System property to set to ignore the thread context ClassLoader.
      Since:
      2.1
      See Also:

  • Method Details

    • getClassLoader

      public static ClassLoader getClassLoader()
      Returns the ClassLoader to use.
      Returns:
      the ClassLoader.
      Since:
      2.22.0

    • getClassLoader

      public static ClassLoader getClassLoader(Class<?> class1, Class<?> class2)
      Since:
      2.22.0

    • getThreadContextClassLoader

      public static ClassLoader getThreadContextClassLoader()
      Looks up the ClassLoader for this current thread. If this class does not have the runtime permission getClassLoader, then the only ClassLoader this attempts to look up is the loader behind this class. When a SecurityManager is installed, this attempts to make a privileged call to get the current thread context ClassLoader, falling back to either the ClassLoader of this class or the system ClassLoader. When no SecurityManager is present, the same lookups are performed without use of AccessController. If none of these strategies can obtain a ClassLoader, then this returns null.
      Returns:
      the current thread's ClassLoader, a fallback loader, or null if no fallback can be determined

    • isClassAvailable

      public static boolean isClassAvailable(String className)
      Determines if a named Class can be loaded or not.
      Parameters:
      className - The class name.
      Returns:
      true if the class could be found or false otherwise.
      Since:
      2.7

    • loadClass

      public static Class<?> loadClass(String className) throws ClassNotFoundException
      Loads a class by name. This method respects the IGNORE_TCCL_PROPERTY Log4j property. If this property is specified and set to anything besides false, then the default ClassLoader will be used.
      Parameters:
      className - fully qualified class name to load
      Returns:
      the loaded class
      Throws:
      ClassNotFoundException - if the specified class name could not be found
      ExceptionInInitializerError - if an exception is thrown during class initialization
      LinkageError - if the linkage of the class fails for any other reason
      Since:
      2.1

    • loadClassUnchecked

      public static Class<?> loadClassUnchecked(String className)
      Loads and initializes a class given its fully qualified class name. All checked reflective operation exceptions are translated into equivalent LinkageError classes.
      Parameters:
      className - fully qualified class name to load
      Returns:
      the loaded class
      Throws:
      NoClassDefFoundError - if the specified class name could not be found
      ExceptionInInitializerError - if an exception is thrown during class initialization
      LinkageError - if the linkage of the class fails for any other reason
      Since:
      2.22.0
      See Also:

    • newInstanceOf

      public static <T> T newInstanceOf(Class<T> clazz) throws InstantiationException, IllegalAccessException, InvocationTargetException, NoSuchMethodException
      Loads and instantiates a Class using the default constructor.
      Type Parameters:
      T - the type of the class modeled by the Class object.
      Parameters:
      clazz - The class.
      Returns:
      new instance of the class.
      Throws:
      NoSuchMethodException - if no zero-arg constructor exists
      SecurityException - if this class is not allowed to access declared members of the provided class
      IllegalAccessException - if the class can't be instantiated through a public constructor
      InstantiationException - if the provided class is abstract or an interface
      InvocationTargetException - if an exception is thrown by the constructor
      ExceptionInInitializerError - if an exception was thrown while initializing the class
      Since:
      2.7

    • newInstanceOfUnchecked

      public static <T> T newInstanceOfUnchecked(Class<T> clazz)
      Creates an instance of the provided class using the default constructor. All checked reflective operation exceptions are translated into LinkageError or InternalException.
      Type Parameters:
      T - the type of the object being instantiated
      Parameters:
      clazz - class to instantiate
      Returns:
      instance of the class
      Throws:
      NoSuchMethodError - if no zero-arg constructor exists
      SecurityException - if this class is not allowed to access declared members of the provided class
      InternalException - if an exception is thrown by the constructor
      InstantiationError - if the provided class is abstract or an interface
      IllegalAccessError - if the class cannot be accessed
      Since:
      2.22.0

    • newInstanceOf

      public static <T> T newInstanceOf(String className) throws ClassNotFoundException, IllegalAccessException, InstantiationException, InvocationTargetException, NoSuchMethodException
      Loads and instantiates a Class using the default constructor.
      Type Parameters:
      T - type the class must be compatible with
      Parameters:
      className - fully qualified class name to load, initialize, and construct
      Returns:
      new instance of the class
      Throws:
      ClassNotFoundException - if the class isn't available to the usual ClassLoaders
      ExceptionInInitializerError - if an exception was thrown while initializing the class
      LinkageError - if the linkage of the class fails for any other reason
      ClassCastException - if the class is not compatible with the generic type parameter provided
      NoSuchMethodException - if no zero-arg constructor exists
      SecurityException - if this class is not allowed to access declared members of the provided class
      IllegalAccessException - if the class can't be instantiated through a public constructor
      InstantiationException - if the provided class is abstract or an interface
      InvocationTargetException - if an exception is thrown by the constructor
      Since:
      2.1

    • newCheckedInstanceOfProperty

      public static <T> T newCheckedInstanceOfProperty(String propertyName, Class<T> clazz) throws ClassNotFoundException, InvocationTargetException, InstantiationException, IllegalAccessException, NoSuchMethodException
      Loads and instantiates a class given by a property name.
      Type Parameters:
      T - The type to cast it to.
      Parameters:
      propertyName - The property name to look up a class name for.
      clazz - The class to cast it to.
      Returns:
      new instance of the class given in the property or null if the property was unset.
      Throws:
      ClassNotFoundException - if the class isn't available to the usual ClassLoaders
      ExceptionInInitializerError - if an exception was thrown while initializing the class
      LinkageError - if the linkage of the class fails for any other reason
      ClassCastException - if the class is not compatible with the generic type parameter provided
      NoSuchMethodException - if no zero-arg constructor exists
      SecurityException - if this class is not allowed to access declared members of the provided class
      IllegalAccessException - if the class can't be instantiated through a public constructor
      InstantiationException - if the provided class is abstract or an interface
      InvocationTargetException - if an exception is thrown by the constructor
      Since:
      2.5

    • newCheckedInstanceOfProperty

      public static <T> T newCheckedInstanceOfProperty(String propertyName, Class<T> clazz, Supplier<T> defaultSupplier) throws ClassNotFoundException, InvocationTargetException, InstantiationException, IllegalAccessException, NoSuchMethodException
      Loads and instantiates a class given by a property name.
      Type Parameters:
      T - The type to cast it to.
      Parameters:
      propertyName - The property name to look up a class name for.
      clazz - The class to cast it to.
      defaultSupplier - Supplier of a default value if the property is not present.
      Returns:
      new instance of the class given in the property or null if the property was unset.
      Throws:
      ClassNotFoundException - if the class isn't available to the usual ClassLoaders
      ExceptionInInitializerError - if an exception was thrown while initializing the class
      LinkageError - if the linkage of the class fails for any other reason
      ClassCastException - if the class is not compatible with the generic type parameter provided
      NoSuchMethodException - if no zero-arg constructor exists
      SecurityException - if this class is not allowed to access declared members of the provided class
      IllegalAccessException - if the class can't be instantiated through a public constructor
      InstantiationException - if the provided class is abstract or an interface
      InvocationTargetException - if an exception is thrown by the constructor
      Since:
      2.22.0

    • newInstanceOfUnchecked

      public static <T> T newInstanceOfUnchecked(String className)
      Loads and instantiates a class by name using its default constructor. All checked reflective operation exceptions are translated into corresponding LinkageError classes.
      Type Parameters:
      T - type the class must be compatible with
      Parameters:
      className - fully qualified class name to load, initialize, and construct
      Returns:
      new instance of the class
      Throws:
      NoClassDefFoundError - if the specified class name could not be found
      ExceptionInInitializerError - if an exception is thrown during class initialization
      ClassCastException - if the class is not compatible with the generic type parameter provided
      NoSuchMethodError - if no zero-arg constructor exists
      SecurityException - if this class is not allowed to access declared members of the provided class
      InternalException - if an exception is thrown by the constructor
      InstantiationError - if the provided class is abstract or an interface
      IllegalAccessError - if the class cannot be accessed
      LinkageError - if the linkage of the class fails for any other reason
      Since:
      2.22.0

    • newCheckedInstanceOf

      public static <T> T newCheckedInstanceOf(String className, Class<T> clazz) throws ClassNotFoundException, InvocationTargetException, InstantiationException, IllegalAccessException, NoSuchMethodException
      Loads and instantiates a derived class using its default constructor.
      Type Parameters:
      T - The type of the class to check.
      Parameters:
      className - The class name.
      clazz - The class to cast it to.
      Returns:
      new instance of the class cast to T
      Throws:
      ClassNotFoundException - if the class isn't available to the usual ClassLoaders
      ExceptionInInitializerError - if an exception is thrown during class initialization
      LinkageError - if the linkage of the class fails for any other reason
      ClassCastException - if the constructed object isn't type compatible with T
      NoSuchMethodException - if no zero-arg constructor exists
      SecurityException - if this class is not allowed to access declared members of the provided class
      IllegalAccessException - if the class can't be instantiated through a public constructor
      InstantiationException - if the provided class is abstract or an interface
      InvocationTargetException - if there was an exception whilst constructing the class
      Since:
      2.1

    • newInstanceOfUnchecked

      public static <T> T newInstanceOfUnchecked(String className, Class<T> supertype)
      Loads the provided class by name as a checked subtype of the given class. All checked reflective operation exceptions are translated into corresponding LinkageError classes.
      Type Parameters:
      T - type of instance to return
      Parameters:
      className - fully qualified class name to load
      supertype - supertype of the class being loaded
      Returns:
      new instance of the requested class
      Throws:
      NoClassDefFoundError - if the provided class name could not be found
      ExceptionInInitializerError - if an exception is thrown during class initialization
      ClassCastException - if the loaded class is not a subtype of the provided class
      NoSuchMethodError - if no zero-arg constructor exists
      SecurityException - if this class is not allowed to access declared members of the provided class
      InternalException - if an exception is thrown by the constructor
      InstantiationError - if the provided class is abstract or an interface
      IllegalAccessError - if the class cannot be accessed
      LinkageError - if the linkage of the class fails for any other reason
      Since:
      2.22.0

    • findResources

      public static Collection<URL> findResources(String resource)
      Finds classpath resources.
      Parameters:
      resource - the name of the resource to find.
      Returns:
      a Collection of URLs matching the resource name. If no resources could be found, then this will be empty.
      Since:
      2.1