net.bytebuddy.implementation.bind.annotation.FieldGetterHandle Maven / Gradle / Ivy
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/*
* 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.implementation.bind.annotation;
import net.bytebuddy.description.annotation.AnnotationDescription;
import net.bytebuddy.description.field.FieldDescription;
import net.bytebuddy.description.method.MethodDescription;
import net.bytebuddy.description.method.MethodList;
import net.bytebuddy.description.method.ParameterDescription;
import net.bytebuddy.description.type.TypeDefinition;
import net.bytebuddy.description.type.TypeDescription;
import net.bytebuddy.description.type.TypeList;
import net.bytebuddy.implementation.Implementation;
import net.bytebuddy.implementation.bind.MethodDelegationBinder;
import net.bytebuddy.implementation.bytecode.StackManipulation;
import net.bytebuddy.implementation.bytecode.assign.Assigner;
import net.bytebuddy.implementation.bytecode.member.MethodInvocation;
import net.bytebuddy.implementation.bytecode.member.MethodVariableAccess;
import net.bytebuddy.utility.JavaConstant;
import net.bytebuddy.utility.JavaType;
import net.bytebuddy.jar.asm.Opcodes;
import java.lang.annotation.*;
import static net.bytebuddy.matcher.ElementMatchers.named;
/**
*
* Assigns a {@code java.lang.invoke.MethodHandle} to the annotated parameter which represents a getter of the represented field.
* For a binding to be valid, the instrumented type must be able to access a field of the given name.
*
*
* Setting {@link FieldGetterHandle#value()} is optional. If the value is not set, the field value attempts to bind a setter's
* or getter's field if the intercepted method is an accessor method. Otherwise, the binding renders the target method
* to be an illegal candidate for binding.
*
*
* Important: Don't confuse this annotation with {@link net.bytebuddy.asm.Advice.FieldGetterHandle} or
* {@link net.bytebuddy.asm.MemberSubstitution.FieldSetterHandle}. This annotation should be used with
* {@link net.bytebuddy.implementation.MethodDelegation} only.
*
*
* @see net.bytebuddy.implementation.MethodDelegation
* @see TargetMethodAnnotationDrivenBinder
* @see RuntimeType
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.PARAMETER)
public @interface FieldGetterHandle {
/**
* The name of the field to be accessed.
*
* @return The name of the field.
*/
String value() default TargetMethodAnnotationDrivenBinder.ParameterBinder.ForFieldBinding.BEAN_PROPERTY;
/**
* Defines the type on which the field is declared. If this value is not set, the most specific type's field is read,
* if two fields with the same name exist in the same type hierarchy.
*
* @return The type that declares the accessed field.
*/
Class declaringType() default void.class;
/**
* Binds a {@link FieldGetterHandle} annotation.
*/
enum Binder implements TargetMethodAnnotationDrivenBinder.ParameterBinder {
/**
* The singleton instance.
*/
INSTANCE(new Delegate());
/**
* The annotation method that for the defining type.
*/
private static final MethodDescription.InDefinedShape DECLARING_TYPE;
/**
* The annotation method for the field's name.
*/
private static final MethodDescription.InDefinedShape FIELD_NAME;
/*
* Initializes the methods of the annotation that is read by this binder.
*/
static {
MethodList methodList = TypeDescription.ForLoadedType.of(FieldGetterHandle.class).getDeclaredMethods();
DECLARING_TYPE = methodList.filter(named("declaringType")).getOnly();
FIELD_NAME = methodList.filter(named("value")).getOnly();
}
/**
* A delegate parameter binder responsible for binding the parameter.
*/
private final TargetMethodAnnotationDrivenBinder.ParameterBinder delegate;
/**
* Creates a new binder for a {@link FieldGetterHandle}.
*
* @param delegate A delegate parameter binder responsible for binding the parameter.
*/
Binder(TargetMethodAnnotationDrivenBinder.ParameterBinder delegate) {
this.delegate = delegate;
}
/**
* {@inheritDoc}
*/
public Class getHandledType() {
return delegate.getHandledType();
}
/**
* {@inheritDoc}
*/
public MethodDelegationBinder.ParameterBinding bind(AnnotationDescription.Loadable annotation,
MethodDescription source,
ParameterDescription target,
Implementation.Target implementationTarget,
Assigner assigner,
Assigner.Typing typing) {
return delegate.bind(annotation, source, target, implementationTarget, assigner, typing);
}
/**
* A delegate implementation for the {@link FieldGetterHandle.Binder}.
*/
protected static class Delegate extends ForFieldBinding {
/**
* {@inheritDoc}
*/
public Class getHandledType() {
return FieldGetterHandle.class;
}
@Override
protected String fieldName(AnnotationDescription.Loadable annotation) {
return annotation.getValue(FIELD_NAME).resolve(String.class);
}
@Override
protected TypeDescription declaringType(AnnotationDescription.Loadable annotation) {
return annotation.getValue(DECLARING_TYPE).resolve(TypeDescription.class);
}
@Override
protected MethodDelegationBinder.ParameterBinding bind(FieldDescription fieldDescription,
AnnotationDescription.Loadable annotation,
MethodDescription source,
ParameterDescription target,
Implementation.Target implementationTarget,
Assigner assigner) {
if (!target.getType().asErasure().isAssignableFrom(JavaType.METHOD_HANDLE.getTypeStub())) {
throw new IllegalStateException("Cannot assign method handle to " + target);
} else if (fieldDescription.isStatic()) {
return new MethodDelegationBinder.ParameterBinding.Anonymous(JavaConstant.MethodHandle.ofGetter(fieldDescription.asDefined()).toStackManipulation());
} else {
return new MethodDelegationBinder.ParameterBinding.Anonymous(new StackManipulation.Compound(
JavaConstant.MethodHandle.ofGetter(fieldDescription.asDefined()).toStackManipulation(),
MethodVariableAccess.loadThis(),
MethodInvocation.invoke(new MethodDescription.Latent(JavaType.METHOD_HANDLE.getTypeStub(), new MethodDescription.Token("bindTo",
Opcodes.ACC_PUBLIC,
JavaType.METHOD_HANDLE.getTypeStub().asGenericType(),
new TypeList.Generic.Explicit(TypeDefinition.Sort.describe(Object.class)))))));
}
}
}
}
}