package net.bytebuddy.dynamic.loading;
import lombok.EqualsAndHashCode;
import net.bytebuddy.description.type.TypeDescription;
import java.io.File;
import java.lang.instrument.Instrumentation;
import java.security.ProtectionDomain;
import java.util.Map;
/**
* A strategy for loading a collection of types.
*
* @param <T> The least specific type of class loader this strategy can apply to.
*/
public interface ClassLoadingStrategy<T extends ClassLoader> {
/**
* A type-safe constant representing the bootstrap class loader which is represented by {@code null} within Java.
*/
ClassLoader BOOTSTRAP_LOADER = null;
/**
* An undefined protection domain.
*/
ProtectionDomain NO_PROTECTION_DOMAIN = null;
/**
* Loads a given collection of classes given their binary representation.
*
* @param classLoader The class loader to used for loading the classes.
* @param types Byte array representations of the types to be loaded mapped by their descriptions,
* where an iteration order defines an order in which they are supposed to be loaded,
* if relevant.
* @return A collection of the loaded classes which will be initialized in the iteration order of the
* returned collection.
*/
Map<TypeDescription, Class<?>> load(T classLoader, Map<TypeDescription, byte[]> types);
/**
* This class contains implementations of default class loading strategies.
*/
enum Default implements Configurable<ClassLoader> {
/**
* This strategy creates a new {@link net.bytebuddy.dynamic.loading.ByteArrayClassLoader} with the given
* class loader as its parent. The byte array class loader is aware of a any dynamically created type and can
* natively load the given classes. This allows to load classes with cyclic load-time dependencies since the
* byte array class loader is queried on each encountered unknown class. Due to the encapsulation of the
* classes that were loaded by a byte array class loader, this strategy will lead to the unloading of these
* classes once this class loader, its classes or any instances of these classes become unreachable.
*/
WRAPPER(new WrappingDispatcher(ByteArrayClassLoader.PersistenceHandler.LATENT, WrappingDispatcher.PARENT_FIRST)),
/**
* The strategy is identical to {@link ClassLoadingStrategy.Default#WRAPPER} but exposes
* the byte arrays that represent a class by {@link java.lang.ClassLoader#getResourceAsStream(String)}. For
* this purpose, all class files are persisted as byte arrays withing the wrapping class loader.
*/
WRAPPER_PERSISTENT(new WrappingDispatcher(ByteArrayClassLoader.PersistenceHandler.MANIFEST, WrappingDispatcher.PARENT_FIRST)),
/**
* <p>
* The child-first class loading strategy is a modified version of the
* {@link ClassLoadingStrategy.Default#WRAPPER} where the dynamic types are given
* priority over any types of a parent class loader with the same name.
* </p>
* <p>
* <b>Important</b>: This does <i>not</i> replace a type of the same name, but it makes the type invisible by
* the reach of this class loader.
* </p>
*/
CHILD_FIRST(new WrappingDispatcher(ByteArrayClassLoader.PersistenceHandler.LATENT, WrappingDispatcher.CHILD_FIRST)),
/**
* The strategy is identical to {@link ClassLoadingStrategy.Default#CHILD_FIRST} but
* exposes the byte arrays that represent a class by {@link java.lang.ClassLoader#getResourceAsStream(String)}.
* For this purpose, all class files are persisted as byte arrays withing the wrapping class loader.
*/
CHILD_FIRST_PERSISTENT(new WrappingDispatcher(ByteArrayClassLoader.PersistenceHandler.MANIFEST, WrappingDispatcher.CHILD_FIRST)),
/**
* <p>
* This strategy does not create a new class loader but injects all classes into the given {@link java.lang.ClassLoader}
* by reflective access. This prevents the loading of classes with cyclic load-time dependencies but avoids the
* creation of an additional class loader. The advantage of this strategy is that the loaded classes will have
* package-private access to other classes within their package of the class loader into which they are
* injected what is not permitted when the wrapper class loader is used. This strategy is implemented using a
* {@link net.bytebuddy.dynamic.loading.ClassInjector.UsingReflection}. Note that this strategy usually yields
* a better runtime performance.
* </p>
* <p>
* <b>Important</b>: This class loader does not define packages for injected classes by default. Therefore, calls to
* {@link Class#getPackage()} might return {@code null}. Packages are only defined
* </p>
*/
INJECTION(new InjectionDispatcher());
/**
* The default behavior when attempting to load a type that was already loaded.
*/
private static final boolean DEFAULT_FORBID_EXISTING = true;
/**
* The dispatcher to be used when loading a class.
*/
private final Configurable<ClassLoader> dispatcher;
/**
* Creates a new default class loading strategy.
*
* @param dispatcher The dispatcher to be used when loading a class.
*/
Default(Configurable<ClassLoader> dispatcher) {
this.dispatcher = dispatcher;
}
@Override
public Map<TypeDescription, Class<?>> load(ClassLoader classLoader, Map<TypeDescription, byte[]> types) {
return dispatcher.load(classLoader, types);
}
@Override
public Configurable<ClassLoader> with(ProtectionDomain protectionDomain) {
return dispatcher.with(protectionDomain);
}
@Override
public Configurable<ClassLoader> with(PackageDefinitionStrategy packageDefinitionStrategy) {
return dispatcher.with(packageDefinitionStrategy);
}
@Override
public Configurable<ClassLoader> allowExistingTypes() {
return dispatcher.allowExistingTypes();
}
/**
* A class loading strategy which applies a class loader injection while applying a given
* {@link java.security.ProtectionDomain} on class injection.
*/
@EqualsAndHashCode
protected static class InjectionDispatcher implements ClassLoadingStrategy.Configurable<ClassLoader> {
/**
* The protection domain to apply.
*/
private final ProtectionDomain protectionDomain;
/**
* The package definer to be used for querying information on package information.
*/
private final PackageDefinitionStrategy packageDefinitionStrategy;
/**
* Determines if an exception should be thrown when attempting to load a type that already exists.
*/
private final boolean forbidExisting;
/**
* Creates a new injection dispatcher.
*/
protected InjectionDispatcher() {
this(NO_PROTECTION_DOMAIN, PackageDefinitionStrategy.NoOp.INSTANCE, DEFAULT_FORBID_EXISTING);
}
/**
* Creates a new injection dispatcher.
*
* @param protectionDomain The protection domain to apply.
* @param packageDefinitionStrategy The package definer to be used for querying information on package information.
* @param forbidExisting Determines if an exception should be thrown when attempting to load a type that already exists.
*/
private InjectionDispatcher(ProtectionDomain protectionDomain,
PackageDefinitionStrategy packageDefinitionStrategy,
boolean forbidExisting) {
this.protectionDomain = protectionDomain;
this.packageDefinitionStrategy = packageDefinitionStrategy;
this.forbidExisting = forbidExisting;
}
@Override
public Map<TypeDescription, Class<?>> load(ClassLoader classLoader, Map<TypeDescription, byte[]> types) {
return new ClassInjector.UsingReflection(classLoader,
protectionDomain,
packageDefinitionStrategy,
forbidExisting).inject(types);
}
@Override
public Configurable<ClassLoader> with(ProtectionDomain protectionDomain) {
return new InjectionDispatcher(protectionDomain, packageDefinitionStrategy, forbidExisting);
}
@Override
public Configurable<ClassLoader> with(PackageDefinitionStrategy packageDefinitionStrategy) {
return new InjectionDispatcher(protectionDomain, packageDefinitionStrategy, forbidExisting);
}
@Override
public Configurable<ClassLoader> allowExistingTypes() {
return new InjectionDispatcher(protectionDomain, packageDefinitionStrategy, false);
}
}
/**
* A class loading strategy which creates a wrapping class loader while applying a given
* {@link java.security.ProtectionDomain} on class loading.
*/
@EqualsAndHashCode
protected static class WrappingDispatcher implements ClassLoadingStrategy.Configurable<ClassLoader> {
/**
* Indicates that a child first loading strategy should be attempted.
*/
private static final boolean CHILD_FIRST = true;
/**
* Indicates that a parent first loading strategy should be attempted.
*/
private static final boolean PARENT_FIRST = false;
/**
* The protection domain to apply.
*/
private final ProtectionDomain protectionDomain;
/**
* The persistence handler to apply.
*/
private final ByteArrayClassLoader.PersistenceHandler persistenceHandler;
/**
* The package definer to be used for querying information on package information.
*/
private final PackageDefinitionStrategy packageDefinitionStrategy;
/**
* {@code true} if the created class loader should apply child-first semantics.
*/
private final boolean childFirst;
/**
* Determines if an exception should be thrown when attempting to load a type that already exists.
*/
private final boolean forbidExisting;
/**
* Creates a new wrapping dispatcher with a default protection domain and a default access control context.
*
* @param persistenceHandler The persistence handler to apply.
* @param childFirst {@code true} if the created class loader should apply child-first semantics.
*/
protected WrappingDispatcher(ByteArrayClassLoader.PersistenceHandler persistenceHandler, boolean childFirst) {
this(NO_PROTECTION_DOMAIN,
PackageDefinitionStrategy.Trivial.INSTANCE,
persistenceHandler,
childFirst,
DEFAULT_FORBID_EXISTING);
}
/**
* Creates a new protection domain specific class loading wrapper.
*
* @param protectionDomain The protection domain to apply.
* @param packageDefinitionStrategy The package definer to be used for querying information on package information.
* @param persistenceHandler The persistence handler to apply.
* @param childFirst {@code true} if the created class loader should apply child-first semantics.
* @param forbidExisting Determines if an exception should be thrown when attempting to load a type that already exists.
*/
private WrappingDispatcher(ProtectionDomain protectionDomain,
PackageDefinitionStrategy packageDefinitionStrategy,
ByteArrayClassLoader.PersistenceHandler persistenceHandler,
boolean childFirst,
boolean forbidExisting) {
this.protectionDomain = protectionDomain;
this.packageDefinitionStrategy = packageDefinitionStrategy;
this.persistenceHandler = persistenceHandler;
this.childFirst = childFirst;
this.forbidExisting = forbidExisting;
}
@Override
public Map<TypeDescription, Class<?>> load(ClassLoader classLoader, Map<TypeDescription, byte[]> types) {
return ByteArrayClassLoader.load(classLoader,
types,
protectionDomain,
persistenceHandler,
packageDefinitionStrategy,
childFirst,
forbidExisting);
}
@Override
public Configurable<ClassLoader> with(ProtectionDomain protectionDomain) {
return new WrappingDispatcher(protectionDomain, packageDefinitionStrategy, persistenceHandler, childFirst, forbidExisting);
}
@Override
public Configurable<ClassLoader> with(PackageDefinitionStrategy packageDefinitionStrategy) {
return new WrappingDispatcher(protectionDomain, packageDefinitionStrategy, persistenceHandler, childFirst, forbidExisting);
}
@Override
public Configurable<ClassLoader> allowExistingTypes() {
return new InjectionDispatcher(protectionDomain, packageDefinitionStrategy, false);
}
}
}
/**
* A {@link ClassLoadingStrategy} that allows configuring the strategy's behavior.
*
* @param <S> The least specific type of class loader this strategy can apply to.
*/
interface Configurable<S extends ClassLoader> extends ClassLoadingStrategy<S> {
/**
* Overrides the implicitly set default {@link java.security.ProtectionDomain} with an explicit one.
*
* @param protectionDomain The protection domain to apply.
* @return This class loading strategy with an explicitly set {@link java.security.ProtectionDomain}.
*/
Configurable<S> with(ProtectionDomain protectionDomain);
/**
* Defines the supplied package definition strategy to be used for defining packages.
*
* @param packageDefinitionStrategy The package definer to be used.
* @return A version of this class loading strategy that applies the supplied package definition strategy.
*/
Configurable<S> with(PackageDefinitionStrategy packageDefinitionStrategy);
/**
* Determines if this class loading strategy should not throw an exception when attempting to load a class that
* was already loaded. In this case, the already loaded class is used instead of the generated class.
*
* @return A version of this class loading strategy that does not throw an exception when a class is already loaded.
*/
Configurable<S> allowExistingTypes();
}
/**
* A class loading strategy that uses a {@code java.lang.invoke.MethodHandles$Lookup} instance for defining types.
* A lookup instance can define types only in the same class loader and in the same package as the type within which
* it was created. The supplied lookup must have package privileges, i.e. it must not be a public lookup.
*/
@EqualsAndHashCode
class UsingLookup implements ClassLoadingStrategy<ClassLoader> {
/**
* The class injector to use.
*/
private final ClassInjector classInjector;
/**
* The class loader in the supplied class injector defines classes.
*/
private final ClassLoader classLoader;
/**
* Creaes a new class loading strategy that uses a lookup type.
*
* @param classInjector The class injector to use.
* @param classLoader The class loader in the supplied class injector defines classes.
*/
protected UsingLookup(ClassInjector classInjector, ClassLoader classLoader) {
this.classInjector = classInjector;
this.classLoader = classLoader;
}
/**
* Creates a new class loading strategy that uses a {@code java.lang.invoke.MethodHandles$Lookup} instance.
*
* @param lookup The lookup instance to use for defining new types.
* @return A suitable class loading strategy.
*/
public static ClassLoadingStrategy<ClassLoader> of(Object lookup) {
ClassInjector.UsingLookup classInjector = ClassInjector.UsingLookup.of(lookup);
return new UsingLookup(classInjector, classInjector.lookupType().getClassLoader());
}
@Override
public Map<TypeDescription, Class<?>> load(ClassLoader classLoader, Map<TypeDescription, byte[]> types) {
if (classLoader != this.classLoader) {
throw new IllegalStateException("Cannot define a type in " + classLoader + " with lookup based on " + this.classLoader);
}
return classInjector.inject(types);
}
}
/**
* A class loading strategy which allows class injection into the bootstrap class loader if
* appropriate.
*/
@EqualsAndHashCode
class ForBootstrapInjection implements ClassLoadingStrategy<ClassLoader> {
/**
* The instrumentation to use.
*/
private final Instrumentation instrumentation;
/**
* The folder to save jar files in.
*/
private final File folder;
/**
* Creates a new injector which is capable of injecting classes into the bootstrap class loader.
*
* @param instrumentation The instrumentation to use.
* @param folder The folder to save jar files in.
*/
public ForBootstrapInjection(Instrumentation instrumentation, File folder) {
this.instrumentation = instrumentation;
this.folder = folder;
}
@Override
public Map<TypeDescription, Class<?>> load(ClassLoader classLoader, Map<TypeDescription, byte[]> types) {
ClassInjector classInjector = classLoader == null
? ClassInjector.UsingInstrumentation.of(folder, ClassInjector.UsingInstrumentation.Target.BOOTSTRAP, instrumentation)
: new ClassInjector.UsingReflection(classLoader);
return classInjector.inject(types);
}
}
/**
* A class loading strategy that injects a class using {@code sun.misc.Unsafe}.
*/
@EqualsAndHashCode
class ForUnsafeInjection implements ClassLoadingStrategy<ClassLoader> {
/**
* The protection domain to use.
*/
private final ProtectionDomain protectionDomain;
/**
* Creates a new class loading strategy for unsafe injection with a default protection domain.
*/
public ForUnsafeInjection() {
this(NO_PROTECTION_DOMAIN);
}
/**
* Creates a new class loading strategy for unsafe injection.
*
* @param protectionDomain The protection domain to use.
*/
public ForUnsafeInjection(ProtectionDomain protectionDomain) {
this.protectionDomain = protectionDomain;
}
@Override
public Map<TypeDescription, Class<?>> load(ClassLoader classLoader, Map<TypeDescription, byte[]> types) {
return new ClassInjector.UsingUnsafe(classLoader, protectionDomain).inject(types);
}
}
}