/*
* Copyright 2002-2009 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.context.support;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;
import org.springframework.core.DecoratingClassLoader;
import org.springframework.core.OverridingClassLoader;
import org.springframework.core.SmartClassLoader;
import org.springframework.util.ReflectionUtils;
/**
* Special variant of an overriding ClassLoader, used for temporary type
* matching in {@link AbstractApplicationContext}. Redefines classes from
* a cached byte array for every <code>loadClass</code> call in order to
* pick up recently loaded types in the parent ClassLoader.
*
* @author Juergen Hoeller
* @since 2.5
* @see AbstractApplicationContext
* @see org.springframework.beans.factory.config.ConfigurableBeanFactory#setTempClassLoader
*/
class ContextTypeMatchClassLoader extends DecoratingClassLoader implements SmartClassLoader {
private static Method findLoadedClassMethod;
static {
try {
findLoadedClassMethod = ClassLoader.class.getDeclaredMethod("findLoadedClass", new Class[] {String.class});
}
catch (NoSuchMethodException ex) {
throw new IllegalStateException("Invalid [java.lang.ClassLoader] class: no 'findLoadedClass' method defined!");
}
}
/** Cache for byte array per class name */
private final Map<String, byte[]> bytesCache = new HashMap<String, byte[]>();
public ContextTypeMatchClassLoader(ClassLoader parent) {
super(parent);
}
@Override
public Class loadClass(String name) throws ClassNotFoundException {
return new ContextOverridingClassLoader(getParent()).loadClass(name);
}
public boolean isClassReloadable(Class clazz) {
return (clazz.getClassLoader() instanceof ContextOverridingClassLoader);
}
/**
* ClassLoader to be created for each loaded class.
* Caches class file content but redefines class for each call.
*/
private class ContextOverridingClassLoader extends OverridingClassLoader {
public ContextOverridingClassLoader(ClassLoader parent) {
super(parent);
}
@Override
protected boolean isEligibleForOverriding(String className) {
if (isExcluded(className) || ContextTypeMatchClassLoader.this.isExcluded(className)) {
return false;
}
ReflectionUtils.makeAccessible(findLoadedClassMethod);
ClassLoader parent = getParent();
while (parent != null) {
if (ReflectionUtils.invokeMethod(findLoadedClassMethod, parent, className) != null) {
return false;
}
parent = parent.getParent();
}
return true;
}
@Override
protected Class loadClassForOverriding(String name) throws ClassNotFoundException {
byte[] bytes = bytesCache.get(name);
if (bytes == null) {
bytes = loadBytesForClass(name);
if (bytes != null) {
bytesCache.put(name, bytes);
}
else {
return null;
}
}
return defineClass(name, bytes, 0, bytes.length);
}
}
}
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