g_cglib.net.sf.cglib.proxy.Enhancer Maven / Gradle / Ivy
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/*
* Copyright 2002,2003,2004 The Apache Software Foundation
*
* 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 g_cglib.net.sf.cglib.proxy;
import java.lang.ref.WeakReference;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.security.ProtectionDomain;
import java.util.*;
import g_cglib.net.sf.cglib.core.*;
import g_asm.org.objectweb.asm.ClassVisitor;
import g_asm.org.objectweb.asm.Type;
import g_asm.org.objectweb.asm.Label;
/**
* Generates dynamic subclasses to enable method interception. This
* class started as a substitute for the standard Dynamic Proxy support
* included with JDK 1.3, but one that allowed the proxies to extend a
* concrete base class, in addition to implementing interfaces. The dynamically
* generated subclasses override the non-final methods of the superclass and
* have hooks which callback to user-defined interceptor
* implementations.
*
* The original and most general callback type is the {@link MethodInterceptor}, which
* in AOP terms enables "around advice"--that is, you can invoke custom code both before
* and after the invocation of the "super" method. In addition you can modify the
* arguments before calling the super method, or not call it at all.
*
* Although MethodInterceptor is generic enough to meet any
* interception need, it is often overkill. For simplicity and performance, additional
* specialized callback types, such as {@link LazyLoader} are also available.
* Often a single callback will be used per enhanced class, but you can control
* which callback is used on a per-method basis with a {@link CallbackFilter}.
*
* The most common uses of this class are embodied in the static helper methods. For
* advanced needs, such as customizing the ClassLoader to use, you should create
* a new instance of Enhancer. Other classes within CGLIB follow a similar pattern.
*
* All enhanced objects implement the {@link Factory} interface, unless {@link #setUseFactory} is
* used to explicitly disable this feature. The Factory interface provides an API
* to change the callbacks of an existing object, as well as a faster and easier way to create
* new instances of the same type.
*
* For an almost drop-in replacement for
* java.lang.reflect.Proxy, see the {@link Proxy} class.
*/
public class Enhancer extends AbstractClassGenerator
{
private static final CallbackFilter ALL_ZERO = new CallbackFilter(){
public int accept(Method method) {
return 0;
}
};
private static final Source SOURCE = new Source(Enhancer.class.getName());
private static final EnhancerKey KEY_FACTORY =
(EnhancerKey)KeyFactory.create(EnhancerKey.class, KeyFactory.HASH_ASM_TYPE, null);
private static final String BOUND_FIELD = "CGLIB$BOUND";
private static final String FACTORY_DATA_FIELD = "CGLIB$FACTORY_DATA";
private static final String THREAD_CALLBACKS_FIELD = "CGLIB$THREAD_CALLBACKS";
private static final String STATIC_CALLBACKS_FIELD = "CGLIB$STATIC_CALLBACKS";
private static final String SET_THREAD_CALLBACKS_NAME = "CGLIB$SET_THREAD_CALLBACKS";
private static final String SET_STATIC_CALLBACKS_NAME = "CGLIB$SET_STATIC_CALLBACKS";
private static final String CONSTRUCTED_FIELD = "CGLIB$CONSTRUCTED";
/**
* {@link g_cglib.net.sf.cglib.core.AbstractClassGenerator.ClassLoaderData#generatedClasses} requires to keep cache key
* in a good shape (the keys should be up and running if the proxy class is alive), and one of the cache keys is
* {@link CallbackFilter}. That is why the generated class contains static field that keeps strong reference to
* the {@link #filter}.
*
This dance achieves two goals: ensures generated class is reusable and available through generatedClasses
* cache, and it enables to unload classloader and the related {@link CallbackFilter} in case user does not need
* that
*/
private static final String CALLBACK_FILTER_FIELD = "CGLIB$CALLBACK_FILTER";
private static final Type OBJECT_TYPE =
TypeUtils.parseType("Object");
private static final Type FACTORY =
TypeUtils.parseType("g_cglib.net.sf.cglib.proxy.Factory");
private static final Type ILLEGAL_STATE_EXCEPTION =
TypeUtils.parseType("IllegalStateException");
private static final Type ILLEGAL_ARGUMENT_EXCEPTION =
TypeUtils.parseType("IllegalArgumentException");
private static final Type THREAD_LOCAL =
TypeUtils.parseType("ThreadLocal");
private static final Type CALLBACK =
TypeUtils.parseType("g_cglib.net.sf.cglib.proxy.Callback");
private static final Type CALLBACK_ARRAY =
Type.getType(Callback[].class);
private static final Signature CSTRUCT_NULL =
TypeUtils.parseConstructor("");
private static final Signature SET_THREAD_CALLBACKS =
new Signature(SET_THREAD_CALLBACKS_NAME, Type.VOID_TYPE, new Type[]{ CALLBACK_ARRAY });
private static final Signature SET_STATIC_CALLBACKS =
new Signature(SET_STATIC_CALLBACKS_NAME, Type.VOID_TYPE, new Type[]{ CALLBACK_ARRAY });
private static final Signature NEW_INSTANCE =
new Signature("newInstance", Constants.TYPE_OBJECT, new Type[]{ CALLBACK_ARRAY });
private static final Signature MULTIARG_NEW_INSTANCE =
new Signature("newInstance", Constants.TYPE_OBJECT, new Type[]{
Constants.TYPE_CLASS_ARRAY,
Constants.TYPE_OBJECT_ARRAY,
CALLBACK_ARRAY,
});
private static final Signature SINGLE_NEW_INSTANCE =
new Signature("newInstance", Constants.TYPE_OBJECT, new Type[]{ CALLBACK });
private static final Signature SET_CALLBACK =
new Signature("setCallback", Type.VOID_TYPE, new Type[]{ Type.INT_TYPE, CALLBACK });
private static final Signature GET_CALLBACK =
new Signature("getCallback", CALLBACK, new Type[]{ Type.INT_TYPE });
private static final Signature SET_CALLBACKS =
new Signature("setCallbacks", Type.VOID_TYPE, new Type[]{ CALLBACK_ARRAY });
private static final Signature GET_CALLBACKS =
new Signature("getCallbacks", CALLBACK_ARRAY, new Type[0]);
private static final Signature THREAD_LOCAL_GET =
TypeUtils.parseSignature("Object get()");
private static final Signature THREAD_LOCAL_SET =
TypeUtils.parseSignature("void set(Object)");
private static final Signature BIND_CALLBACKS =
TypeUtils.parseSignature("void CGLIB$BIND_CALLBACKS(Object)");
private EnhancerFactoryData currentData;
private Object currentKey;
/** Internal interface, only public due to ClassLoader issues. */
public interface EnhancerKey {
public Object newInstance(String type,
String[] interfaces,
WeakCacheKey filter,
Type[] callbackTypes,
boolean useFactory,
boolean interceptDuringConstruction,
Long serialVersionUID);
}
private Class[] interfaces;
private CallbackFilter filter;
private Callback[] callbacks;
private Type[] callbackTypes;
private boolean validateCallbackTypes;
private boolean classOnly;
private Class superclass;
private Class[] argumentTypes;
private Object[] arguments;
private boolean useFactory = true;
private Long serialVersionUID;
private boolean interceptDuringConstruction = true;
/**
* Create a new Enhancer. A new Enhancer
* object should be used for each generated object, and should not
* be shared across threads. To create additional instances of a
* generated class, use the Factory interface.
* @see Factory
*/
public Enhancer() {
super(SOURCE);
}
/**
* Set the class which the generated class will extend. As a convenience,
* if the supplied superclass is actually an interface, setInterfaces
* will be called with the appropriate argument instead.
* A non-interface argument must not be declared as final, and must have an
* accessible constructor.
* @param superclass class to extend or interface to implement
* @see #setInterfaces(Class[])
*/
public void setSuperclass(Class superclass) {
if (superclass != null && superclass.isInterface()) {
setInterfaces(new Class[]{ superclass });
} else if (superclass != null && superclass.equals(Object.class)) {
// affects choice of ClassLoader
this.superclass = null;
} else {
this.superclass = superclass;
}
}
/**
* Set the interfaces to implement. The Factory interface will
* always be implemented regardless of what is specified here.
* @param interfaces array of interfaces to implement, or null
* @see Factory
*/
public void setInterfaces(Class[] interfaces) {
this.interfaces = interfaces;
}
/**
* Set the {@link CallbackFilter} used to map the generated class' methods
* to a particular callback index.
* New object instances will always use the same mapping, but may use different
* actual callback objects.
* @param filter the callback filter to use when generating a new class
* @see #setCallbacks
*/
public void setCallbackFilter(CallbackFilter filter) {
this.filter = filter;
}
/**
* Set the single {@link Callback} to use.
* Ignored if you use {@link #createClass}.
* @param callback the callback to use for all methods
* @see #setCallbacks
*/
public void setCallback(final Callback callback) {
setCallbacks(new Callback[]{ callback });
}
/**
* Set the array of callbacks to use.
* Ignored if you use {@link #createClass}.
* You must use a {@link CallbackFilter} to specify the index into this
* array for each method in the proxied class.
* @param callbacks the callback array
* @see #setCallbackFilter
* @see #setCallback
*/
public void setCallbacks(Callback[] callbacks) {
if (callbacks != null && callbacks.length == 0) {
throw new IllegalArgumentException("Array cannot be empty");
}
this.callbacks = callbacks;
}
/**
* Set whether the enhanced object instances should implement
* the {@link Factory} interface.
* This was added for tools that need for proxies to be more
* indistinguishable from their targets. Also, in some cases it may
* be necessary to disable the Factory interface to
* prevent code from changing the underlying callbacks.
* @param useFactory whether to implement Factory; default is true
*/
public void setUseFactory(boolean useFactory) {
this.useFactory = useFactory;
}
/**
* Set whether methods called from within the proxy's constructer
* will be intercepted. The default value is true. Unintercepted methods
* will call the method of the proxy's base class, if it exists.
* @param interceptDuringConstruction whether to intercept methods called from the constructor
*/
public void setInterceptDuringConstruction(boolean interceptDuringConstruction) {
this.interceptDuringConstruction = interceptDuringConstruction;
}
/**
* Set the single type of {@link Callback} to use.
* This may be used instead of {@link #setCallback} when calling
* {@link #createClass}, since it may not be possible to have
* an array of actual callback instances.
* @param callbackType the type of callback to use for all methods
* @see #setCallbackTypes
*/
public void setCallbackType(Class callbackType) {
setCallbackTypes(new Class[]{ callbackType });
}
/**
* Set the array of callback types to use.
* This may be used instead of {@link #setCallbacks} when calling
* {@link #createClass}, since it may not be possible to have
* an array of actual callback instances.
* You must use a {@link CallbackFilter} to specify the index into this
* array for each method in the proxied class.
* @param callbackTypes the array of callback types
*/
public void setCallbackTypes(Class[] callbackTypes) {
if (callbackTypes != null && callbackTypes.length == 0) {
throw new IllegalArgumentException("Array cannot be empty");
}
this.callbackTypes = CallbackInfo.determineTypes(callbackTypes);
}
/**
* Generate a new class if necessary and uses the specified
* callbacks (if any) to create a new object instance.
* Uses the no-arg constructor of the superclass.
* @return a new instance
*/
public Object create() {
classOnly = false;
argumentTypes = null;
return createHelper();
}
/**
* Generate a new class if necessary and uses the specified
* callbacks (if any) to create a new object instance.
* Uses the constructor of the superclass matching the argumentTypes
* parameter, with the given arguments.
* @param argumentTypes constructor signature
* @param arguments compatible wrapped arguments to pass to constructor
* @return a new instance
*/
public Object create(Class[] argumentTypes, Object[] arguments) {
classOnly = false;
if (argumentTypes == null || arguments == null || argumentTypes.length != arguments.length) {
throw new IllegalArgumentException("Arguments must be non-null and of equal length");
}
this.argumentTypes = argumentTypes;
this.arguments = arguments;
return createHelper();
}
/**
* Generate a new class if necessary and return it without creating a new instance.
* This ignores any callbacks that have been set.
* To create a new instance you will have to use reflection, and methods
* called during the constructor will not be intercepted. To avoid this problem,
* use the multi-arg create method.
* @see #create(Class[], Object[])
*/
public Class createClass() {
classOnly = true;
return (Class)createHelper();
}
/**
* Insert a static serialVersionUID field into the generated class.
* @param sUID the field value, or null to avoid generating field.
*/
public void setSerialVersionUID(Long sUID) {
serialVersionUID = sUID;
}
private void preValidate() {
if (callbackTypes == null) {
callbackTypes = CallbackInfo.determineTypes(callbacks, false);
validateCallbackTypes = true;
}
if (filter == null) {
if (callbackTypes.length > 1) {
throw new IllegalStateException("Multiple callback types possible but no filter specified");
}
filter = ALL_ZERO;
}
}
private void validate() {
if (classOnly ^ (callbacks == null)) {
if (classOnly) {
throw new IllegalStateException("createClass does not accept callbacks");
} else {
throw new IllegalStateException("Callbacks are required");
}
}
if (classOnly && (callbackTypes == null)) {
throw new IllegalStateException("Callback types are required");
}
if (validateCallbackTypes) {
callbackTypes = null;
}
if (callbacks != null && callbackTypes != null) {
if (callbacks.length != callbackTypes.length) {
throw new IllegalStateException("Lengths of callback and callback types array must be the same");
}
Type[] check = CallbackInfo.determineTypes(callbacks);
for (int i = 0; i < check.length; i++) {
if (!check[i].equals(callbackTypes[i])) {
throw new IllegalStateException("Callback " + check[i] + " is not assignable to " + callbackTypes[i]);
}
}
} else if (callbacks != null) {
callbackTypes = CallbackInfo.determineTypes(callbacks);
}
if (interfaces != null) {
for (int i = 0; i < interfaces.length; i++) {
if (interfaces[i] == null) {
throw new IllegalStateException("Interfaces cannot be null");
}
if (!interfaces[i].isInterface()) {
throw new IllegalStateException(interfaces[i] + " is not an interface");
}
}
}
}
/**
* The idea of the class is to cache relevant java.lang.reflect instances so
* proxy-class can be instantiated faster that when using {@link ReflectUtils#newInstance(Class, Class[], Object[])}
* and {@link Enhancer#setThreadCallbacks(Class, Callback[])}
*/
static class EnhancerFactoryData {
public final Class generatedClass;
private final Method setThreadCallbacks;
private final Class[] primaryConstructorArgTypes;
private final Constructor primaryConstructor;
public EnhancerFactoryData(Class generatedClass, Class[] primaryConstructorArgTypes, boolean classOnly) {
this.generatedClass = generatedClass;
try {
setThreadCallbacks = getCallbacksSetter(generatedClass, SET_THREAD_CALLBACKS_NAME);
if (classOnly) {
this.primaryConstructorArgTypes = null;
this.primaryConstructor = null;
} else {
this.primaryConstructorArgTypes = primaryConstructorArgTypes;
this.primaryConstructor = ReflectUtils.getConstructor(generatedClass, primaryConstructorArgTypes);
}
} catch (NoSuchMethodException e) {
throw new CodeGenerationException(e);
}
}
/**
* Creates proxy instance for given argument types, and assigns the callbacks.
* Ideally, for each proxy class, just one set of argument types should be used,
* otherwise it would have to spend time on constructor lookup.
* Technically, it is a re-implementation of {@link Enhancer#createUsingReflection(Class)},
* with "cache {@link #setThreadCallbacks} and {@link #primaryConstructor}"
*
* @see #createUsingReflection(Class)
* @param argumentTypes constructor argument types
* @param arguments constructor arguments
* @param callbacks callbacks to set for the new instance
* @return newly created proxy
*/
public Object newInstance(Class[] argumentTypes, Object[] arguments, Callback[] callbacks) {
setThreadCallbacks(callbacks);
try {
// Explicit reference equality is added here just in case Arrays.equals does not have one
if (primaryConstructorArgTypes == argumentTypes ||
Arrays.equals(primaryConstructorArgTypes, argumentTypes)) {
// If we have relevant Constructor instance at hand, just call it
// This skips "get constructors" machinery
return ReflectUtils.newInstance(primaryConstructor, arguments);
}
// Take a slow path if observing unexpected argument types
return ReflectUtils.newInstance(generatedClass, argumentTypes, arguments);
} finally {
// clear thread callbacks to allow them to be gc'd
setThreadCallbacks(null);
}
}
private void setThreadCallbacks(Callback[] callbacks) {
try {
setThreadCallbacks.invoke(generatedClass, (Object) callbacks);
} catch (IllegalAccessException e) {
throw new CodeGenerationException(e);
} catch (InvocationTargetException e) {
throw new CodeGenerationException(e.getTargetException());
}
}
}
private Object createHelper() {
preValidate();
Object key = KEY_FACTORY.newInstance((superclass != null) ? superclass.getName() : null,
ReflectUtils.getNames(interfaces),
filter == ALL_ZERO ? null : new WeakCacheKey(filter),
callbackTypes,
useFactory,
interceptDuringConstruction,
serialVersionUID);
this.currentKey = key;
Object result = super.create(key);
return result;
}
@Override
protected Class generate(ClassLoaderData data) {
validate();
if (superclass != null) {
setNamePrefix(superclass.getName());
} else if (interfaces != null) {
setNamePrefix(interfaces[ReflectUtils.findPackageProtected(interfaces)].getName());
}
return super.generate(data);
}
protected ClassLoader getDefaultClassLoader() {
if (superclass != null) {
return superclass.getClassLoader();
} else if (interfaces != null) {
return interfaces[0].getClassLoader();
} else {
return null;
}
}
protected ProtectionDomain getProtectionDomain() {
if (superclass != null) {
return ReflectUtils.getProtectionDomain(superclass);
} else if (interfaces != null) {
return ReflectUtils.getProtectionDomain(interfaces[0]);
} else {
return null;
}
}
private Signature rename(Signature sig, int index) {
return new Signature("CGLIB$" + sig.getName() + "$" + index,
sig.getDescriptor());
}
/**
* Finds all of the methods that will be extended by an
* Enhancer-generated class using the specified superclass and
* interfaces. This can be useful in building a list of Callback
* objects. The methods are added to the end of the given list. Due
* to the subclassing nature of the classes generated by Enhancer,
* the methods are guaranteed to be non-static, non-final, and
* non-private. Each method signature will only occur once, even if
* it occurs in multiple classes.
* @param superclass the class that will be extended, or null
* @param interfaces the list of interfaces that will be implemented, or null
* @param methods the list into which to copy the applicable methods
*/
public static void getMethods(Class superclass, Class[] interfaces, List methods)
{
getMethods(superclass, interfaces, methods, null, null);
}
private static void getMethods(Class superclass, Class[] interfaces, List methods, List interfaceMethods, Set forcePublic)
{
ReflectUtils.addAllMethods(superclass, methods);
List target = (interfaceMethods != null) ? interfaceMethods : methods;
if (interfaces != null) {
for (int i = 0; i < interfaces.length; i++) {
if (interfaces[i] != Factory.class) {
ReflectUtils.addAllMethods(interfaces[i], target);
}
}
}
if (interfaceMethods != null) {
if (forcePublic != null) {
forcePublic.addAll(MethodWrapper.createSet(interfaceMethods));
}
methods.addAll(interfaceMethods);
}
CollectionUtils.filter(methods, new RejectModifierPredicate(Constants.ACC_STATIC));
CollectionUtils.filter(methods, new VisibilityPredicate(superclass, true));
CollectionUtils.filter(methods, new DuplicatesPredicate(methods));
CollectionUtils.filter(methods, new RejectModifierPredicate(Constants.ACC_FINAL));
}
public void generateClass(ClassVisitor v) throws Exception {
Class sc = (superclass == null) ? Object.class : superclass;
if (TypeUtils.isFinal(sc.getModifiers()))
throw new IllegalArgumentException("Cannot subclass final class " + sc.getName());
List constructors = new ArrayList(Arrays.asList(sc.getDeclaredConstructors()));
filterConstructors(sc, constructors);
// Order is very important: must add superclass, then
// its superclass chain, then each interface and
// its superinterfaces.
List actualMethods = new ArrayList();
List interfaceMethods = new ArrayList();
final Set forcePublic = new HashSet();
getMethods(sc, interfaces, actualMethods, interfaceMethods, forcePublic);
List methods = CollectionUtils.transform(actualMethods, new Transformer() {
public Object transform(Object value) {
Method method = (Method)value;
int modifiers = Constants.ACC_FINAL
| (method.getModifiers()
& ~Constants.ACC_ABSTRACT
& ~Constants.ACC_NATIVE
& ~Constants.ACC_SYNCHRONIZED);
if (forcePublic.contains(MethodWrapper.create(method))) {
modifiers = (modifiers & ~Constants.ACC_PROTECTED) | Constants.ACC_PUBLIC;
}
return ReflectUtils.getMethodInfo(method, modifiers);
}
});
ClassEmitter e = new ClassEmitter(v);
if (currentData == null) {
e.begin_class(Constants.V1_8,
Constants.ACC_PUBLIC,
getClassName(),
Type.getType(sc),
(useFactory ?
TypeUtils.add(TypeUtils.getTypes(interfaces), FACTORY) :
TypeUtils.getTypes(interfaces)),
Constants.SOURCE_FILE);
} else {
e.begin_class(Constants.V1_8,
Constants.ACC_PUBLIC,
getClassName(),
null,
new Type[]{FACTORY},
Constants.SOURCE_FILE);
}
List constructorInfo = CollectionUtils.transform(constructors, MethodInfoTransformer.getInstance());
e.declare_field(Constants.ACC_PRIVATE, BOUND_FIELD, Type.BOOLEAN_TYPE, null);
e.declare_field(Constants.ACC_PUBLIC | Constants.ACC_STATIC, FACTORY_DATA_FIELD, OBJECT_TYPE, null);
if (!interceptDuringConstruction) {
e.declare_field(Constants.ACC_PRIVATE, CONSTRUCTED_FIELD, Type.BOOLEAN_TYPE, null);
}
e.declare_field(Constants.PRIVATE_FINAL_STATIC, THREAD_CALLBACKS_FIELD, THREAD_LOCAL, null);
e.declare_field(Constants.PRIVATE_FINAL_STATIC, STATIC_CALLBACKS_FIELD, CALLBACK_ARRAY, null);
if (serialVersionUID != null) {
e.declare_field(Constants.PRIVATE_FINAL_STATIC, Constants.SUID_FIELD_NAME, Type.LONG_TYPE, serialVersionUID);
}
for (int i = 0; i < callbackTypes.length; i++) {
e.declare_field(Constants.ACC_PRIVATE, getCallbackField(i), callbackTypes[i], null);
}
// This is declared private to avoid "public field" pollution
e.declare_field(Constants.ACC_PRIVATE | Constants.ACC_STATIC, CALLBACK_FILTER_FIELD, OBJECT_TYPE, null);
if (currentData == null) {
emitMethods(e, methods, actualMethods);
emitConstructors(e, constructorInfo);
} else {
emitDefaultConstructor(e);
}
emitSetThreadCallbacks(e);
emitSetStaticCallbacks(e);
emitBindCallbacks(e);
if (useFactory || currentData != null) {
int[] keys = getCallbackKeys();
emitNewInstanceCallbacks(e);
emitNewInstanceCallback(e);
emitNewInstanceMultiarg(e, constructorInfo);
emitGetCallback(e, keys);
emitSetCallback(e, keys);
emitGetCallbacks(e);
emitSetCallbacks(e);
}
e.end_class();
}
/**
* Filter the list of constructors from the superclass. The
* constructors which remain will be included in the generated
* class. The default implementation is to filter out all private
* constructors, but subclasses may extend Enhancer to override this
* behavior.
* @param sc the superclass
* @param constructors the list of all declared constructors from the superclass
* @throws IllegalArgumentException if there are no non-private constructors
*/
protected void filterConstructors(Class sc, List constructors) {
CollectionUtils.filter(constructors, new VisibilityPredicate(sc, true));
if (constructors.size() == 0)
throw new IllegalArgumentException("No visible constructors in " + sc);
}
/**
* This method should not be called in regular flow.
* Technically speaking {@link #wrapCachedClass(Class)} uses {@link EnhancerFactoryData} as a cache value,
* and the latter enables faster instantiation than plain old reflection lookup and invoke.
* This method is left intact for backward compatibility reasons: just in case it was ever used.
*
* @param type class to instantiate
* @return newly created proxy instance
* @throws Exception if something goes wrong
*/
protected Object firstInstance(Class type) throws Exception {
if (classOnly) {
return type;
} else {
return createUsingReflection(type);
}
}
protected Object nextInstance(Object instance) {
EnhancerFactoryData data = (EnhancerFactoryData) instance;
if (classOnly) {
return data.generatedClass;
}
Class[] argumentTypes = this.argumentTypes;
Object[] arguments = this.arguments;
if (argumentTypes == null) {
argumentTypes = Constants.EMPTY_CLASS_ARRAY;
arguments = null;
}
return data.newInstance(argumentTypes, arguments, callbacks);
}
@Override
protected Object wrapCachedClass(Class klass) {
Class[] argumentTypes = this.argumentTypes;
if (argumentTypes == null) {
argumentTypes = Constants.EMPTY_CLASS_ARRAY;
}
EnhancerFactoryData factoryData = new EnhancerFactoryData(klass, argumentTypes, classOnly);
Field factoryDataField = null;
try {
// The subsequent dance is performed just once for each class,
// so it does not matter much how fast it goes
factoryDataField = klass.getField(FACTORY_DATA_FIELD);
factoryDataField.set(null, factoryData);
Field callbackFilterField = klass.getDeclaredField(CALLBACK_FILTER_FIELD);
callbackFilterField.setAccessible(true);
callbackFilterField.set(null, this.filter);
} catch (NoSuchFieldException e) {
throw new CodeGenerationException(e);
} catch (IllegalAccessException e) {
throw new CodeGenerationException(e);
}
return new WeakReference(factoryData);
}
@Override
protected Object unwrapCachedValue(Object cached) {
if (currentKey instanceof EnhancerKey) {
EnhancerFactoryData data = ((WeakReference) cached).get();
return data;
}
return super.unwrapCachedValue(cached);
}
/**
* Call this method to register the {@link Callback} array to use before
* creating a new instance of the generated class via reflection. If you are using
* an instance of Enhancer or the {@link Factory} interface to create
* new instances, this method is unnecessary. Its primary use is for when you want to
* cache and reuse a generated class yourself, and the generated class does
* not implement the {@link Factory} interface.
*
* Note that this method only registers the callbacks on the current thread.
* If you want to register callbacks for instances created by multiple threads,
* use {@link #registerStaticCallbacks}.
*
* The registered callbacks are overwritten and subsequently cleared
* when calling any of the create methods (such as
* {@link #create}), or any {@link Factory} newInstance method.
* Otherwise they are not cleared, and you should be careful to set them
* back to null after creating new instances via reflection if
* memory leakage is a concern.
* @param generatedClass a class previously created by {@link Enhancer}
* @param callbacks the array of callbacks to use when instances of the generated
* class are created
* @see #setUseFactory
*/
public static void registerCallbacks(Class generatedClass, Callback[] callbacks) {
setThreadCallbacks(generatedClass, callbacks);
}
/**
* Similar to {@link #registerCallbacks}, but suitable for use
* when multiple threads will be creating instances of the generated class.
* The thread-level callbacks will always override the static callbacks.
* Static callbacks are never cleared.
* @param generatedClass a class previously created by {@link Enhancer}
* @param callbacks the array of callbacks to use when instances of the generated
* class are created
*/
public static void registerStaticCallbacks(Class generatedClass, Callback[] callbacks) {
setCallbacksHelper(generatedClass, callbacks, SET_STATIC_CALLBACKS_NAME);
}
/**
* Determine if a class was generated using Enhancer.
* @param type any class
* @return whether the class was generated using Enhancer
*/
public static boolean isEnhanced(Class type) {
try {
getCallbacksSetter(type, SET_THREAD_CALLBACKS_NAME);
return true;
} catch (NoSuchMethodException e) {
return false;
}
}
private static void setThreadCallbacks(Class type, Callback[] callbacks) {
setCallbacksHelper(type, callbacks, SET_THREAD_CALLBACKS_NAME);
}
private static void setCallbacksHelper(Class type, Callback[] callbacks, String methodName) {
// TODO: optimize
try {
Method setter = getCallbacksSetter(type, methodName);
setter.invoke(null, new Object[]{ callbacks });
} catch (NoSuchMethodException e) {
throw new IllegalArgumentException(type + " is not an enhanced class");
} catch (IllegalAccessException e) {
throw new CodeGenerationException(e);
} catch (InvocationTargetException e) {
throw new CodeGenerationException(e);
}
}
private static Method getCallbacksSetter(Class type, String methodName) throws NoSuchMethodException {
return type.getDeclaredMethod(methodName, new Class[]{ Callback[].class });
}
/**
* Instantiates a proxy instance and assigns callback values.
* Implementation detail: java.lang.reflect instances are not cached, so this method should not
* be used on a hot path.
* This method is used when {@link #setUseCache(boolean)} is set to {@code false}.
*
* @param type class to instantiate
* @return newly created instance
*/
private Object createUsingReflection(Class type) {
setThreadCallbacks(type, callbacks);
try{
if (argumentTypes != null) {
return ReflectUtils.newInstance(type, argumentTypes, arguments);
} else {
return ReflectUtils.newInstance(type);
}
}finally{
// clear thread callbacks to allow them to be gc'd
setThreadCallbacks(type, null);
}
}
/**
* Helper method to create an intercepted object.
* For finer control over the generated instance, use a new instance of Enhancer
* instead of this static method.
* @param type class to extend or interface to implement
* @param callback the callback to use for all methods
*/
public static Object create(Class type, Callback callback) {
Enhancer e = new Enhancer();
e.setSuperclass(type);
e.setCallback(callback);
return e.create();
}
/**
* Helper method to create an intercepted object.
* For finer control over the generated instance, use a new instance of Enhancer
* instead of this static method.
* @param superclass class to extend or interface to implement
* @param interfaces array of interfaces to implement, or null
* @param callback the callback to use for all methods
*/
public static Object create(Class superclass, Class interfaces[], Callback callback) {
Enhancer e = new Enhancer();
e.setSuperclass(superclass);
e.setInterfaces(interfaces);
e.setCallback(callback);
return e.create();
}
/**
* Helper method to create an intercepted object.
* For finer control over the generated instance, use a new instance of Enhancer
* instead of this static method.
* @param superclass class to extend or interface to implement
* @param interfaces array of interfaces to implement, or null
* @param filter the callback filter to use when generating a new class
* @param callbacks callback implementations to use for the enhanced object
*/
public static Object create(Class superclass, Class[] interfaces, CallbackFilter filter, Callback[] callbacks) {
Enhancer e = new Enhancer();
e.setSuperclass(superclass);
e.setInterfaces(interfaces);
e.setCallbackFilter(filter);
e.setCallbacks(callbacks);
return e.create();
}
private void emitDefaultConstructor(ClassEmitter ce) {
Constructor