Class ResourceUtils

java.lang.Object
org.apache.commons.discovery.tools.ResourceUtils

public class ResourceUtils extends Object
Mechanisms to locate and load a class. The load methods locate a class only. The find methods locate a class and verify that the class implements an given interface or extends a given class.
  • Constructor Details

  • Method Details

    • getPackageName

      public static String getPackageName(Class<?> clazz)
      Get package name. Not all class loaders 'keep' package information, in which case Class.getPackage() returns null. This means that calling Class.getPackage().getName() is unreliable at best.
      Parameters:
      clazz - The class from which the package has to be extracted
      Returns:
      The string representation of the input class package
    • getResource

      public static Resource getResource(Class<?> spi, String resourceName, ClassLoaders loaders) throws DiscoveryException
      Load the resource resourceName. Try each classloader in succession, until first succeeds, or all fail. If all fail and resouceName is not absolute (doesn't start with '/' character), then retry with packageName/resourceName after changing all '.' to '/'.
      Parameters:
      spi - The SPI type
      resourceName - The name of the resource to load.
      loaders - the class loaders holder
      Returns:
      The discovered Resource instance
      Throws:
      DiscoveryException - if the class implementing the SPI cannot be found, cannot be loaded and instantiated, or if the resulting class does not implement (or extend) the SPI
    • loadProperties

      public static Properties loadProperties(Class<?> spi, String propertiesFileName, ClassLoaders classLoaders) throws DiscoveryException
      Load named property file, optionally qualified by spi's package name as per Class.getResource. A property file is loaded using the following sequence of class loaders:
      • Thread Context Class Loader
      • DiscoverSingleton's Caller's Class Loader
      • SPI's Class Loader
      • DiscoverSingleton's (this class) Class Loader
      • System Class Loader
      Parameters:
      spi - The SPI type
      propertiesFileName - The property file name.
      classLoaders - The class loaders holder
      Returns:
      The loaded named property file, in Properties format
      Throws:
      DiscoveryException - Thrown if the name of a class implementing the SPI cannot be found, if the class cannot be loaded and instantiated, or if the resulting class does not implement (or extend) the SPI.