com.google.inject.internal.ProviderMethod Maven / Gradle / Ivy
/*
* Copyright (C) 2008 Google Inc.
*
* 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 com.google.inject.internal;
import com.google.common.base.Objects;
import com.google.common.collect.ImmutableSet;
import com.google.inject.Binder;
import com.google.inject.Exposed;
import com.google.inject.Key;
import com.google.inject.PrivateBinder;
import com.google.inject.Provides;
import com.google.inject.internal.InternalProviderInstanceBindingImpl.InitializationTiming;
import com.google.inject.internal.util.StackTraceElements;
import com.google.inject.spi.BindingTargetVisitor;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.HasDependencies;
import com.google.inject.spi.ProviderInstanceBinding;
import com.google.inject.spi.ProviderWithExtensionVisitor;
import com.google.inject.spi.ProvidesMethodBinding;
import com.google.inject.spi.ProvidesMethodTargetVisitor;
import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Set;
import java.util.function.BiFunction;
/**
* A provider that invokes a method and returns its result.
*
* @author [email protected] (Jesse Wilson)
*/
public abstract class ProviderMethod extends InternalProviderInstanceBindingImpl.CyclicFactory
implements HasDependencies, ProvidesMethodBinding, ProviderWithExtensionVisitor {
/**
* Creates a {@link ProviderMethod}.
*
* Unless {@code skipFastClassGeneration} is set, this will use bytecode generation to invoke
* the actual method, since it is significantly faster. However, this may fail if the method is
* {@code private} or {@code protected}, since this approach is subject to java access policies.
*/
static ProviderMethod create(
Key key,
Method method,
Object instance,
ImmutableSet> dependencies,
Class scopeAnnotation,
boolean skipFastClassGeneration,
Annotation annotation) {
int modifiers = method.getModifiers();
if (InternalFlags.isBytecodeGenEnabled() && !skipFastClassGeneration) {
try {
BiFunction fastMethod = BytecodeGen.fastMethod(method);
if (fastMethod != null) {
return new FastClassProviderMethod(
key, method, instance, dependencies, scopeAnnotation, annotation, fastMethod);
}
} catch (Exception | LinkageError e) {
/* fall-through */
}
}
if (!Modifier.isPublic(modifiers)
|| !Modifier.isPublic(method.getDeclaringClass().getModifiers())) {
method.setAccessible(true);
}
return new ReflectionProviderMethod(
key, method, instance, dependencies, scopeAnnotation, annotation);
}
protected final Object instance;
protected final Method method;
private final Key key;
private final Class scopeAnnotation;
private final ImmutableSet> dependencies;
private final boolean exposed;
private final Annotation annotation;
/**
* Set by {@link #initialize(InjectorImpl, Errors)} so it is always available prior to injection.
*/
private SingleParameterInjector[] parameterInjectors;
/** @param method the method to invoke. Its return type must be the same type as {@code key}. */
ProviderMethod(
Key key,
Method method,
Object instance,
ImmutableSet> dependencies,
Class scopeAnnotation,
Annotation annotation) {
// We can be safely initialized eagerly since our bindings must exist statically and it is an
// error for them not to.
super(InitializationTiming.EAGER);
this.key = key;
this.scopeAnnotation = scopeAnnotation;
this.instance = instance;
this.dependencies = dependencies;
this.method = method;
this.exposed = method.isAnnotationPresent(Exposed.class);
this.annotation = annotation;
}
@Override
public Key getKey() {
return key;
}
@Override
public Method getMethod() {
return method;
}
// exposed for GIN
public Object getInstance() {
return instance;
}
@Override
public Object getEnclosingInstance() {
return instance;
}
@Override
public Annotation getAnnotation() {
return annotation;
}
public void configure(Binder binder) {
binder = binder.withSource(method);
if (scopeAnnotation != null) {
binder.bind(key).toProvider(this).in(scopeAnnotation);
} else {
binder.bind(key).toProvider(this);
}
if (exposed) {
// the cast is safe 'cause the only binder we have implements PrivateBinder. If there's a
// misplaced @Exposed, calling this will add an error to the binder's error queue
((PrivateBinder) binder).expose(key);
}
}
@Override
void initialize(InjectorImpl injector, Errors errors) throws ErrorsException {
parameterInjectors = injector.getParametersInjectors(dependencies.asList(), errors);
}
@Override
protected T doProvision(InternalContext context, Dependency dependency)
throws InternalProvisionException {
try {
T t = doProvision(SingleParameterInjector.getAll(context, parameterInjectors));
if (t == null && !dependency.isNullable()) {
InternalProvisionException.onNullInjectedIntoNonNullableDependency(getMethod(), dependency);
}
return t;
} catch (IllegalAccessException e) {
throw new AssertionError(e);
} catch (InvocationTargetException userException) {
Throwable cause = userException.getCause() != null ? userException.getCause() : userException;
throw InternalProvisionException.errorInProvider(cause).addSource(getSource());
}
}
/** Extension point for our subclasses to implement the provisioning strategy. */
abstract T doProvision(Object[] parameters)
throws IllegalAccessException, InvocationTargetException;
@Override
public Set> getDependencies() {
return dependencies;
}
@Override
@SuppressWarnings("unchecked")
public V acceptExtensionVisitor(
BindingTargetVisitor visitor, ProviderInstanceBinding binding) {
if (visitor instanceof ProvidesMethodTargetVisitor) {
return ((ProvidesMethodTargetVisitor) visitor).visit(this);
}
return visitor.visit(binding);
}
@Override
public String toString() {
String annotationString = annotation.toString();
// Show @Provides w/o the com.google.inject prefix.
if (annotation.annotationType() == Provides.class) {
annotationString = "@Provides";
} else if (annotationString.endsWith("()")) {
// Remove the common "()" suffix if there are no values.
annotationString = annotationString.substring(0, annotationString.length() - 2);
}
return annotationString + " " + StackTraceElements.forMember(method);
}
@Override
public boolean equals(Object obj) {
if (obj instanceof ProviderMethod) {
ProviderMethod o = (ProviderMethod) obj;
return method.equals(o.method)
&& Objects.equal(instance, o.instance)
&& annotation.equals(o.annotation);
} else {
return false;
}
}
@Override
public int hashCode() {
// Avoid calling hashCode on 'instance', which is a user-object
// that might not be expecting it.
// (We need to call equals, so we do. But we can avoid hashCode.)
return Objects.hashCode(method, annotation);
}
/**
* A {@link ProviderMethod} implementation that uses bytecode generation to invoke the provider
* method.
*/
private static final class FastClassProviderMethod extends ProviderMethod {
final BiFunction fastMethod;
FastClassProviderMethod(
Key key,
Method method,
Object instance,
ImmutableSet> dependencies,
Class scopeAnnotation,
Annotation annotation,
BiFunction fastMethod) {
super(key, method, instance, dependencies, scopeAnnotation, annotation);
this.fastMethod = fastMethod;
}
@SuppressWarnings("unchecked")
@Override
public T doProvision(Object[] parameters) throws InvocationTargetException {
try {
return (T) fastMethod.apply(instance, parameters);
} catch (Throwable e) {
throw new InvocationTargetException(e); // match JDK reflection behaviour
}
}
}
/**
* A {@link ProviderMethod} implementation that invokes the method using normal java reflection.
*/
private static final class ReflectionProviderMethod extends ProviderMethod {
ReflectionProviderMethod(
Key key,
Method method,
Object instance,
ImmutableSet> dependencies,
Class scopeAnnotation,
Annotation annotation) {
super(key, method, instance, dependencies, scopeAnnotation, annotation);
}
@SuppressWarnings("unchecked")
@Override
T doProvision(Object[] parameters) throws IllegalAccessException, InvocationTargetException {
return (T) method.invoke(instance, parameters);
}
}
}