Package org.apache.logging.log4j.core.util

Class Loader

java.lang.Object
org.apache.logging.log4j.core.util.Loader
public final class Loader extends Object
Load resources (or images) from various sources.

  • Method Details

    • getClassLoader

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

    • getThreadContextClassLoader

      public static ClassLoader getThreadContextClassLoader()
      Returns the ClassLoader of current thread if possible, or falls back to the system ClassLoader if none is available.
      Returns:
      the TCCL.
      See Also:

    • getClassLoader

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

    • getResource

      public static @Nullable URL getResource(String resource, ClassLoader defaultLoader)
      This method will search for resource in different places. The search order is as follows:
      1. Search for resource using the thread context class loader under Java2. If that fails, search for resource using the class loader that loaded this class (Loader). Under JDK 1.1, only the class loader that loaded this class (Loader) is used.
      2. Try one last time with ClassLoader.getSystemResource(resource), that is using the system class loader in JDK 1.2 and virtual machine's built-in class loader in JDK 1.1.
      Parameters:
      resource - The resource to load.
      defaultLoader - The default ClassLoader.
      Returns:
      A URL to the resource or null.

    • getResourceAsStream

      public static InputStream getResourceAsStream(String resource, ClassLoader defaultLoader)
      This method will search for resource in different places. The search order is as follows:
      1. Search for resource using the thread context class loader under Java2. If that fails, search for resource using the class loader that loaded this class (Loader). Under JDK 1.1, only the class loader that loaded this class (Loader) is used.
      2. Try one last time with ClassLoader.getSystemResource(resource), that is using the system class loader in JDK 1.2 and virtual machine's built-in class loader in JDK 1.1.
      Parameters:
      resource - The resource to load.
      defaultLoader - The default ClassLoader.
      Returns:
      An InputStream to read the resouce.

    • initializeClass

      public static Class<?> initializeClass(String className, ClassLoader loader) throws ClassNotFoundException
      Loads and initializes a named Class using a given ClassLoader.
      Parameters:
      className - The class name.
      loader - The class loader.
      Returns:
      The class.
      Throws:
      ClassNotFoundException - if the class could not be found.

    • loadClass

      public static Class<?> loadClass(String className, ClassLoader loader) throws ClassNotFoundException
      Loads a named Class using a given ClassLoader.
      Parameters:
      className - The class name.
      loader - The class loader.
      Returns:
      The class, or null if loader is null.
      Throws:
      ClassNotFoundException - if the class could not be found.

    • loadSystemClass

      public static Class<?> loadSystemClass(String className) throws ClassNotFoundException
      Load a Class in the java.* namespace by name. Useful for peculiar scenarios typically involving Google App Engine.
      Parameters:
      className - The class name.
      Returns:
      The Class.
      Throws:
      ClassNotFoundException - if the Class could not be found.

    • newInstanceOf

      public static <T> T newInstanceOf(String className) throws ClassNotFoundException, IllegalAccessException, InstantiationException, NoSuchMethodException, InvocationTargetException
      Loads and instantiates a Class using the default constructor.
      Parameters:
      className - The class name.
      Returns:
      new instance of the class.
      Throws:
      ClassNotFoundException - if the class isn't available to the usual ClassLoaders
      IllegalAccessException - if the class can't be instantiated through a public constructor
      InstantiationException - if there was an exception whilst instantiating the class
      NoSuchMethodException - if there isn't a no-args constructor on the class
      InvocationTargetException - if there was an exception whilst constructing the class

    • newCheckedInstanceOf

      public static <T> T newCheckedInstanceOf(String className, Class<T> clazz) throws ClassNotFoundException, NoSuchMethodException, IllegalAccessException, InvocationTargetException, InstantiationException
      Loads, instantiates, and casts a Class using the default constructor.
      Type Parameters:
      T - The type to cast it to.
      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
      IllegalAccessException - if the class can't be instantiated through a public constructor
      InstantiationException - if there was an exception whilst instantiating the class
      NoSuchMethodException - if there isn't a no-args constructor on the class
      InvocationTargetException - if there was an exception whilst constructing the class
      ClassCastException - if the constructed object isn't type compatible with T

    • newCheckedInstanceOfProperty

      public static <T> T newCheckedInstanceOfProperty(String propertyName, Class<T> clazz) throws ClassNotFoundException, NoSuchMethodException, InvocationTargetException, InstantiationException, IllegalAccessException
      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
      IllegalAccessException - if the class can't be instantiated through a public constructor
      InstantiationException - if there was an exception whilst instantiating the class
      NoSuchMethodException - if there isn't a no-args constructor on the class
      InvocationTargetException - if there was an exception whilst constructing the class
      ClassCastException - if the constructed object isn't type compatible with T

    • 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.

    • isJansiAvailable

      @Deprecated public static boolean isJansiAvailable()
      Deprecated.
      Since 2.25.0 without a replacement.

    • 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 - The class name.
      Returns:
      the Class for the given name.
      Throws:
      ClassNotFoundException - if the specified class name could not be found