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Explore the source code of the class DefaultCacheKeyResolver.java

/*******************************************************************************
 * Copyright (c) 2012 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:
 *   John Kew (vmware)         initial implementation
 *******************************************************************************/

package org.aspectj.weaver.tools.cache;

import java.net.URL;
import java.net.URLClassLoader;
import java.util.Collections;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.zip.CRC32;

/**
 * Naive default class and classloader hashing implementation useful
 * for some multi-classloader environments.
 * 

* This implementation creates classloader scopes of the form:
* "ExampleClassLoaderName.[crc hash]" *

* And weaved class keys of the form:
* "com.foo.BarClassName.[bytes len][crc].weaved" *

* And generated class keys of the form:
* "com.foo.BarClassName$AjClosure.generated */ public class DefaultCacheKeyResolver implements CacheKeyResolver { public static final String GENERATED_SUFFIX = ".generated"; public static final String WEAVED_SUFFIX = ".weaved"; /** * Create a scope from a set of urls and aspect urls. Creates scope * of the form "ExampleClassLoaderName.[md5sum]" or * "ExampleClassLoaderName.[crc]" * * @param cl the classloader which uses the cache, can be null * @param aspects the aspects * @return a unique string for URLClassloaders, otherwise a non-unique classname */ public String createClassLoaderScope(ClassLoader cl, List aspects) { String name = cl != null ? cl.getClass().getSimpleName() : "unknown"; List hashableStrings = new LinkedList(); StringBuilder hashable = new StringBuilder(256); // Add the list of loader urls to the hash list if (cl != null && cl instanceof URLClassLoader) { URL[] urls = ((URLClassLoader) cl).getURLs(); for (int i = 0; i < urls.length; i++) { hashableStrings.add(urls[i].toString()); } } hashableStrings.addAll(aspects); Collections.sort(hashableStrings); for (Iterator it = hashableStrings.iterator(); it.hasNext(); ) { String url = it.next(); hashable.append(url); } String hash = null; byte[] bytes = hashable.toString().getBytes(); hash = crc(bytes); return name + '.' + hash; } private String crc(byte[] input) { CRC32 crc32 = new CRC32(); crc32.update(input); return String.valueOf(crc32.getValue()); } public String getGeneratedRegex() { return ".*" + GENERATED_SUFFIX; } public String getWeavedRegex() { return ".*" + WEAVED_SUFFIX; } /** * Converts a cache key back to a className * * @param key to convert * @return className, e.g. "com.foo.Bar" */ public String keyToClass(String key) { if (key.endsWith(GENERATED_SUFFIX)) { return key.replaceAll(GENERATED_SUFFIX + "$", ""); } if (key.endsWith(WEAVED_SUFFIX)) { return key.replaceAll("\\.[^.]+" + WEAVED_SUFFIX, ""); } return key; } public CachedClassReference weavedKey(String className, byte[] original_bytes) { String hash = crc(original_bytes); return new CachedClassReference(className + "." + hash + WEAVED_SUFFIX, className); } public CachedClassReference generatedKey(String className) { return new CachedClassReference(className + GENERATED_SUFFIX, className); } }