net.bytebuddy.dynamic.loading.InjectionClassLoader Maven / Gradle / Ivy
/*
* Copyright 2014 - Present Rafael Winterhalter
*
* 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 net.bytebuddy.dynamic.loading;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.utility.nullability.MaybeNull;
import java.lang.reflect.Method;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;
/**
*
* An injection class loader allows for the injection of a class after the class loader was created. Injection is only possible if this class loader is not sealed.
*
*
* Important: Not sealing a class loader allows to break package encapsulation for anybody getting hold of a reference to this class loader.
*
*/
public abstract class InjectionClassLoader extends ClassLoader {
/*
* Register class loader as parallel capable if the current VM supports it.
*/
static {
doRegisterAsParallelCapable();
}
/**
* Registers class loader as parallel capable if possible.
*/
@SuppressFBWarnings(value = "DP_DO_INSIDE_DO_PRIVILEGED", justification = "Must be invoked from targeting class loader type.")
private static void doRegisterAsParallelCapable() {
try {
Method method = ClassLoader.class.getDeclaredMethod("registerAsParallelCapable");
method.setAccessible(true);
method.invoke(null);
} catch (Throwable ignored) {
/* do nothing */
}
}
/**
* Indicates if this class loader is sealed, i.e. forbids runtime injection.
*/
private final AtomicBoolean sealed;
/**
* Creates a new injection class loader.
*
* @param parent The class loader's parent.
* @param sealed Indicates if this class loader is sealed, i.e. forbids runtime injection.
*/
protected InjectionClassLoader(@MaybeNull ClassLoader parent, boolean sealed) {
super(parent);
this.sealed = new AtomicBoolean(sealed);
}
/**
* Returns {@code true} if this class loader is sealed.
*
* @return {@code true} if this class loader is sealed.
*/
public boolean isSealed() {
return sealed.get();
}
/**
* Seals the class loader and returns {@code true} if the class loader was not sealed previously.
*
* @return {@code true} if the class loader was not sealed previously.
*/
public boolean seal() {
return !sealed.getAndSet(true);
}
/**
* Defines a new type to be loaded by this class loader.
*
* @param name The name of the type.
* @param binaryRepresentation The type's binary representation.
* @return The defined class or a previously defined class.
* @throws ClassNotFoundException If the class could not be loaded.
*/
public Class defineClass(String name, byte[] binaryRepresentation) throws ClassNotFoundException {
return defineClasses(Collections.singletonMap(name, binaryRepresentation)).get(name);
}
/**
* Defines a group of types to be loaded by this class loader. If this class loader is sealed, an {@link IllegalStateException} is thrown.
*
* @param typeDefinitions The types binary representations.
* @return The mapping of defined classes or previously defined classes by their name.
* @throws ClassNotFoundException If the class could not be loaded.
*/
public Map> defineClasses(Map typeDefinitions) throws ClassNotFoundException {
if (sealed.get()) {
throw new IllegalStateException("Cannot inject classes into a sealed class loader");
}
return doDefineClasses(typeDefinitions);
}
/**
* Defines a group of types to be loaded by this class loader.
*
* @param typeDefinitions The types binary representations.
* @return The mapping of defined classes or previously defined classes by their name.
* @throws ClassNotFoundException If the class could not be loaded.
*/
protected abstract Map> doDefineClasses(Map typeDefinitions) throws ClassNotFoundException;
/**
* A class loading strategy for adding a type to an injection class loader.
*/
public enum Strategy implements ClassLoadingStrategy {
/**
* The singleton instance.
*/
INSTANCE;
/**
* {@inheritDoc}
*/
public Map> load(@MaybeNull InjectionClassLoader classLoader, Map types) {
if (classLoader == null) {
throw new IllegalArgumentException("Cannot add types to bootstrap class loader: " + types);
}
Map typeDefinitions = new LinkedHashMap();
Map typeDescriptions = new HashMap();
for (Map.Entry entry : types.entrySet()) {
typeDefinitions.put(entry.getKey().getName(), entry.getValue());
typeDescriptions.put(entry.getKey().getName(), entry.getKey());
}
Map> loadedTypes = new HashMap>();
try {
for (Map.Entry> entry : classLoader.defineClasses(typeDefinitions).entrySet()) {
loadedTypes.put(typeDescriptions.get(entry.getKey()), entry.getValue());
}
} catch (ClassNotFoundException exception) {
throw new IllegalStateException("Cannot load classes: " + types, exception);
}
return loadedTypes;
}
}
}