ClassCreator.java

/**************************************************************************************
 * Copyright (c) Jonas Bon?r, Alexandre Vasseur. All rights reserved.                 *
 * http://aspectwerkz.codehaus.org                                                    *
 * ---------------------------------------------------------------------------------- *
 * The software in this package is published under the terms of the LGPL license      *
 * a copy of which has been included with this distribution in the license.txt file.  *
 **************************************************************************************/
package test.aopc;

import org.codehaus.aspectwerkz.exception.WrappedRuntimeException;

import java.io.File;
import java.lang.reflect.Array;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;

/**
 * Test helper for AspectContainer, emulates a ClassLoader hierarchy sys/sub/ sys/sub/a sys/sub/b
 *
 * FIXME - rewrite with ASM
 *
 * @author <a href="mailto:alex@gnilux.com">Alexandre Vasseur </a>
 */
public class ClassCreator {
    /**
     * ClassLoader.defineClass(name, bytes, from, to)
     */
    private static Method CLASSLOADER_DEFINECLASS_METHOD;

    static {
        try {
            Object b = Array.newInstance(byte.class, 1);
            CLASSLOADER_DEFINECLASS_METHOD = ClassLoader.class.getDeclaredMethod(
                    "defineClass",
                    new Class[]{
                        String.class, b.getClass(), int.class, int.class
                    }
            );
            CLASSLOADER_DEFINECLASS_METHOD.setAccessible(true);
        } catch (Throwable t) {
            t.printStackTrace();
        }
    }

    public static Object createInstance(String name, Class classPrototype, ClassLoader loader) {
        try {
            return createClass(name, classPrototype, loader).newInstance();
        } catch (Throwable t) {
            throw new WrappedRuntimeException(t);
        }
    }

    public static Class createClass(String name, Class classPrototype, ClassLoader loader) {
        return classPrototype;
//        try {
//            ClassPool cp = new ClassPool(null);
//            cp.appendClassPath(new LoaderClassPath(loader));
//            CtClass prototype = cp.get(classPrototype.getName());
//            prototype.setName(name);
//            return define(prototype.toBytecode(), name, loader);
//        } catch (Throwable throwable) {
//            throw new WrappedRuntimeException(throwable);
//        }
    }

    public static void main(String[] a) throws Throwable {
        ClassLoader myCL = new URLClassLoader(
                new URL[]{
                    getPathFor(Callable.class.getResource("META-INF/aop.xml"))
                }, ClassLoader.getSystemClassLoader()
        );
        ClassLoader mySubCLA = new URLClassLoader(
                new URL[]{
                    getPathFor(Callable.class.getResource("a/META-INF/aop.xml"))
                }, myCL
        );
        Callable ca = (Callable) (createClass("test.aopc.a.Callee", CallablePrototype.class, mySubCLA)).newInstance();
        ca.methodAround();
        ca.debug();
        ClassLoader mySubCLB = new URLClassLoader(new URL[]{}, myCL);
        Callable cb = (Callable) (createClass("test.aopc.b.Callee", CallablePrototype.class, mySubCLB)).newInstance();
        cb.methodAround();
        cb.debug();
    }

    public static URL getPathFor(URL definition) {
        try {
            System.out.println(definition);
            System.out.println(definition.getFile());
            File f = new File(definition.getFile());
            if (!f.exists()) {
                System.err.println("<WARN> could not find " + f);
            }
            String path = new File(f.getParent()).getParent();
            File testExists = new File(path);
            if (!testExists.isDirectory()) {
                System.err.println("<WARN> could not find " + path);
            }
            return new File(path).toURL();
        } catch (MalformedURLException e) {
            throw new WrappedRuntimeException(e);
        }
    }

    /**
     * Helper to define a Class within a specific ClassLoader
     *
     * @param b
     * @param name
     * @param loader
     * @return @throws Throwable
     */
    public static Class define(byte[] b, String name, ClassLoader loader) throws Throwable {
        Object k = CLASSLOADER_DEFINECLASS_METHOD.invoke(
                loader, new Object[]{
                    name, b, new Integer(0), new Integer(b.length)
                }
        );
        return (Class) k;
    }
}