How to use

onRegistration

method

in

javax.imageio.spi.ImageOutputStreamSpi

/**
 * Upon registration, this method ensures that this SPI will be invoked
 * before the default FileImageOutputStreamSpi
 * 
 * @param registry
 *                ServiceRegistry where this object has been registered.
 * @param category
 *                a Class object indicating the registry category under
 *                which this object has been registered.
 */
@SuppressWarnings("unchecked")
public void onRegistration(ServiceRegistry registry, Class category) {
  super.onRegistration(registry, category);
  Object other;
  final Class targetClass = ImageOutputStreamSpi.class;
  for (Iterator i = registry.getServiceProviders(targetClass, true); i.hasNext();) {
    other = i.next();
    // using class name to avoid warnings in JDK 11
    if (other != null && other.getClass().getName().equals("com.sun.imageio.spi.FileImageOutputStreamSpi"))
      registry.deregisterServiceProvider(other);
    if (this != other) {
      registry.setOrdering(targetClass, this, other);
    }
  }
}

/**
 * Upon registration, this method ensures that this SPI will be invoked
 * before the default FileImageOutputStreamSpi
 * 
 * @param registry
 *                ServiceRegistry where this object has been registered.
 * @param category
 *                a Class object indicating the registry category under
 *                which this object has been registered.
 */
@SuppressWarnings("unchecked")
public void onRegistration(ServiceRegistry registry, Class category) {
  super.onRegistration(registry, category);
  Object other;
  final Class targetClass = ImageOutputStreamSpi.class;
  for (Iterator i = registry.getServiceProviders(targetClass, true); i.hasNext();) {
    other = i.next();
    if (other instanceof FileImageOutputStreamSpi)
      registry.deregisterServiceProvider(other);
    if (this != other) {
      registry.setOrdering(targetClass, this, other);
    }
  }
}