ReflectionUtils.java

package lilypad.bukkit.connect.util;

import java.lang.reflect.Field;
import java.lang.reflect.Modifier;

public class ReflectionUtils {

	private static final Field FIELD_MODIFIERS;
	private static final Field FIELD_ACCESSSOR;
	private static final Field FIELD_ACCESSSOR_OVERRIDE;
	private static final Field FIELD_ROOT;

	static {
		Field fieldModifiers = null;
		Field fieldAccessor = null;
		Field fieldAccessorOverride = null;
		Field fieldRoot = null;
		try {
			fieldModifiers = Field.class.getDeclaredField("modifiers");
			fieldModifiers.setAccessible(true);
			fieldAccessor = Field.class.getDeclaredField("fieldAccessor");
			fieldAccessor.setAccessible(true);
			fieldAccessorOverride = Field.class.getDeclaredField("overrideFieldAccessor");
			fieldAccessorOverride.setAccessible(true);
			fieldRoot = Field.class.getDeclaredField("root");
			fieldRoot.setAccessible(true);
		} catch (Exception exception) {
			exception.printStackTrace();
		}
		FIELD_MODIFIERS = fieldModifiers;
		FIELD_ACCESSSOR = fieldAccessor;
		FIELD_ACCESSSOR_OVERRIDE = fieldAccessorOverride;
		FIELD_ROOT = fieldRoot;
	}

	public static void setFinalField(Class<?> objectClass, Object object, String fieldName, Object value) throws Exception {
		Field field = objectClass.getDeclaredField(fieldName);
		field.setAccessible(true);

		if (Modifier.isFinal(field.getModifiers())) {
			FIELD_MODIFIERS.setInt(field, field.getModifiers() & ~Modifier.FINAL);
			Field currentField = field;
			do {
				FIELD_ACCESSSOR.set(currentField, null);
				FIELD_ACCESSSOR_OVERRIDE.set(currentField, null);
			} while((currentField = (Field) FIELD_ROOT.get(currentField)) != null);
		}
		
		field.set(object, value);
	}

	@SuppressWarnings("unchecked")
	public static <T> T getPrivateField(Class<?> objectClass, Object object, Class<T> fieldClass, String fieldName) throws Exception {
		Field field = objectClass.getDeclaredField(fieldName);
		field.setAccessible(true);
		return (T) field.get(object);
	}

}