org.aspectj/runtime/src/main/java/org/aspectj/lang/Aspects14.java

/*******************************************************************************
 * Copyright (c) 2006 Contributors.
 * All rights reserved.
 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution and is available at
 * http://eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 * variant of Aspects in the aspectj5rt project - this one isn't Java5   - Andy Clement
 *******************************************************************************/
package org.aspectj.lang;


import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

/**
 * For users working on a level of Java prior to Java5, Aspects14 handles generic aspectOf methods when they 
 * are not available in the aspects but added later on through load time weaving.  Users on Java5 should use
 * the class Aspects instead.
 * Aspects14.aspectOf(..) is doing reflective calls to the aspect aspectOf, so for better performance
 * consider using ajc compilation of the aspects and using them as a binary dependancies in your project.
 */
public class Aspects14 {

    private final static Class[] EMPTY_CLASS_ARRAY = new Class[0];
    private final static Class[] PEROBJECT_CLASS_ARRAY = new Class[]{Object.class};
    private final static Class[] PERTYPEWITHIN_CLASS_ARRAY = new Class[]{Class.class};
    private final static Object[] EMPTY_OBJECT_ARRAY = new Object[0];
    private final static String ASPECTOF = "aspectOf";
    private final static String HASASPECT = "hasAspect";

    /**
     * Returns the singleton aspect or the percflow / percflowbelow associated with the current thread
     *
     * @param aspectClass aspect class for which to discover the aspect instance
     * @return an aspect instance
     * @throws NoAspectBoundException if no such aspect
     */
    public static Object aspectOf(Class aspectClass) throws NoAspectBoundException {
        try {
            return getSingletonOrThreadAspectOf(aspectClass).invoke(null, EMPTY_OBJECT_ARRAY);
        } catch (InvocationTargetException e) {
        	//FIXME asc Highly temporary change to see what the build makes of it - dont use 1.4 APIs
            throw new NoAspectBoundException(aspectClass.getName(), e);//e.getCause());
        } catch (Exception e) {
            throw new NoAspectBoundException(aspectClass.getName(), e);
        }
    }

    /**
     * Returns the perthis / pertarget aspect
     * @param aspectClass aspect class for which to discover the aspect instance
     * @param perObject object for which to discover the aspect instance
     * @return an aspect instance
     * @throws NoAspectBoundException if no such aspect, or no aspect bound
     */
    public static Object aspectOf(Class aspectClass, Object perObject) throws NoAspectBoundException {
        try {
            return getPerObjectAspectOf(aspectClass).invoke(null, new Object[]{perObject});
        } catch (InvocationTargetException e) {
        	//FIXME asc Highly temporary change to see what the build makes of it - dont use 1.4 APIs
            throw new NoAspectBoundException(aspectClass.getName(), e);//e.getCause());
        } catch (Exception e) {
            throw new NoAspectBoundException(aspectClass.getName(), e);
        }
    }

    /**
     * Returns the pertypewithin aspect
     * @param aspectClass aspect class for which to discover the aspect instance
     * @param perTypeWithin class
     * @return the aspect instance
     * @throws NoAspectBoundException if no such aspect, or no aspect bound
     */
    public static Object aspectOf(Class aspectClass, Class perTypeWithin) throws NoAspectBoundException {
        try {
            return getPerTypeWithinAspectOf(aspectClass).invoke(null, new Object[]{perTypeWithin});
        } catch (InvocationTargetException e) {
//        	FIXME asc Highly temporary change to see what the build makes of it - dont use 1.4 APIs
            throw new NoAspectBoundException(aspectClass.getName(), e);//e.getCause());
        } catch (Exception e) {
            throw new NoAspectBoundException(aspectClass.getName(), e);
        }
    }

    /**
     * Returns true if singleton aspect or percflow / percflowbelow aspect is bound
     *
     * @param aspectClass aspect class for which to check the aspect instance
     * @return true if an aspect instance is bound
     * @throws NoAspectBoundException if not bound
     */
    public static boolean hasAspect(Class aspectClass) throws NoAspectBoundException {
        try {
            return ((Boolean)getSingletonOrThreadHasAspect(aspectClass).invoke(null, EMPTY_OBJECT_ARRAY)).booleanValue();
        } catch (Exception e) {
            return false;
        }
    }

    /**
     * Returns true if the perthis / pertarget aspect is bound
     * @param aspectClass aspect class for which to check the aspect instance
     * @param perObject the this/target for which to check for an aspect
     * @return true if aspect instance exists for the class/object combination
     * @throws NoAspectBoundException if not bound
     */
    public static boolean hasAspect(Class aspectClass, Object perObject) throws NoAspectBoundException {
        try {
            return ((Boolean)getPerObjectHasAspect(aspectClass).invoke(null, new Object[]{perObject})).booleanValue();
        } catch (Exception e) {
            return false;
        }
    }

    /**
     * Returns true if the pertypewithin aspect is bound
     * @param aspectClass aspect class for which to check the aspect instance
     * @param perTypeWithin class
     * @return true if aspect instance exists for this aspect class/pertypewithin class combination
     * @throws NoAspectBoundException if not bound
     */
    public static boolean hasAspect(Class aspectClass, Class perTypeWithin) throws NoAspectBoundException {
        try {
            return ((Boolean)getPerTypeWithinHasAspect(aspectClass).invoke(null, new Object[]{perTypeWithin})).booleanValue();
        } catch (Exception e) {
            return false;
        }
    }

    // -- aspectOf

    private static Method getSingletonOrThreadAspectOf(Class aspectClass) throws NoSuchMethodException {
        Method method = aspectClass.getDeclaredMethod(ASPECTOF, EMPTY_CLASS_ARRAY);
        return checkAspectOf(method, aspectClass);
    }

    private static Method getPerObjectAspectOf(Class aspectClass) throws NoSuchMethodException {
        Method method = aspectClass.getDeclaredMethod(ASPECTOF, PEROBJECT_CLASS_ARRAY);
        return checkAspectOf(method, aspectClass);
    }

    private static Method getPerTypeWithinAspectOf(Class aspectClass) throws NoSuchMethodException {
        Method method = aspectClass.getDeclaredMethod(ASPECTOF, PERTYPEWITHIN_CLASS_ARRAY);
        return checkAspectOf(method, aspectClass);
    }

    private static Method checkAspectOf(Method method, Class aspectClass) throws NoSuchMethodException {
        method.setAccessible(true);
        if (!method.isAccessible()
            || !Modifier.isPublic(method.getModifiers())
            || !Modifier.isStatic(method.getModifiers())) {            
            throw new NoSuchMethodException(aspectClass.getName() + ".aspectOf(..) is not accessible public static");
        }
        return method;
    }

    // -- hasAspect

    private static Method getSingletonOrThreadHasAspect(Class aspectClass) throws NoSuchMethodException {
        Method method = aspectClass.getDeclaredMethod(HASASPECT, EMPTY_CLASS_ARRAY);
        return checkHasAspect(method, aspectClass);
    }

    private static Method getPerObjectHasAspect(Class aspectClass) throws NoSuchMethodException {
        Method method = aspectClass.getDeclaredMethod(HASASPECT, PEROBJECT_CLASS_ARRAY);
        return checkHasAspect(method, aspectClass);
    }

    private static Method getPerTypeWithinHasAspect(Class aspectClass) throws NoSuchMethodException {
        Method method = aspectClass.getDeclaredMethod(HASASPECT, PERTYPEWITHIN_CLASS_ARRAY);
        return checkHasAspect(method, aspectClass);
    }

    private static Method checkHasAspect(Method method, Class aspectClass) throws NoSuchMethodException {
        method.setAccessible(true);
        if (!method.isAccessible()
            || !Modifier.isPublic(method.getModifiers())
            || !Modifier.isStatic(method.getModifiers())) {
            throw new NoSuchMethodException(aspectClass.getName() + ".hasAspect(..) is not accessible public static");
        }
        return method;
    }
}