com.google.inject.multibindings.MultibindingsScanner Maven / Gradle / Ivy
/**
* Copyright (C) 2015 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.multibindings;
import com.google.common.collect.ImmutableSet;
import com.google.inject.AbstractModule;
import com.google.inject.Binder;
import com.google.inject.Key;
import com.google.inject.Module;
import com.google.inject.TypeLiteral;
import com.google.inject.spi.InjectionPoint;
import com.google.inject.spi.ModuleAnnotatedMethodScanner;
import java.lang.annotation.Annotation;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Set;
/**
* Scans a module for annotations that signal multibindings, mapbindings, and optional bindings.
*
* @since 4.0
*/
public class MultibindingsScanner {
private MultibindingsScanner() {}
/**
* Returns a module that, when installed, will scan all modules for methods with the annotations
* {@literal @}{@link ProvidesIntoMap}, {@literal @}{@link ProvidesIntoSet}, and
* {@literal @}{@link ProvidesIntoOptional}.
*
* This is a convenience method, equivalent to doing
* {@code binder().scanModulesForAnnotatedMethods(MultibindingsScanner.scanner())}.
*/
public static Module asModule() {
return new AbstractModule() {
@Override protected void configure() {
binder().scanModulesForAnnotatedMethods(Scanner.INSTANCE);
}
};
}
/**
* Returns a {@link ModuleAnnotatedMethodScanner} that, when bound, will scan all modules for
* methods with the annotations {@literal @}{@link ProvidesIntoMap},
* {@literal @}{@link ProvidesIntoSet}, and {@literal @}{@link ProvidesIntoOptional}.
*/
public static ModuleAnnotatedMethodScanner scanner() {
return Scanner.INSTANCE;
}
private static class Scanner extends ModuleAnnotatedMethodScanner {
private static final Scanner INSTANCE = new Scanner();
@Override
public Set> annotationClasses() {
return ImmutableSet.of(
ProvidesIntoSet.class, ProvidesIntoMap.class, ProvidesIntoOptional.class);
}
@SuppressWarnings({"unchecked", "rawtypes"}) // mapKey doesn't know its key type
@Override
public Key prepareMethod(Binder binder, Annotation annotation, Key key,
InjectionPoint injectionPoint) {
Method method = (Method) injectionPoint.getMember();
AnnotationOrError mapKey = findMapKeyAnnotation(binder, method);
if (annotation instanceof ProvidesIntoSet) {
if (mapKey.annotation != null) {
binder.addError("Found a MapKey annotation on non map binding at %s.", method);
}
return Multibinder.newRealSetBinder(binder, key).getKeyForNewItem();
} else if (annotation instanceof ProvidesIntoMap) {
if (mapKey.error) {
// Already failed on the MapKey, don't bother doing more work.
return key;
}
if (mapKey.annotation == null) {
// If no MapKey, make an error and abort.
binder.addError("No MapKey found for map binding at %s.", method);
return key;
}
TypeAndValue typeAndValue = typeAndValueOfMapKey(mapKey.annotation);
return MapBinder.newRealMapBinder(binder, typeAndValue.type, key)
.getKeyForNewValue(typeAndValue.value);
} else if (annotation instanceof ProvidesIntoOptional) {
if (mapKey.annotation != null) {
binder.addError("Found a MapKey annotation on non map binding at %s.", method);
}
switch (((ProvidesIntoOptional)annotation).value()) {
case DEFAULT:
return OptionalBinder.newRealOptionalBinder(binder, key).getKeyForDefaultBinding();
case ACTUAL:
return OptionalBinder.newRealOptionalBinder(binder, key).getKeyForActualBinding();
}
}
throw new IllegalStateException("Invalid annotation: " + annotation);
}
}
private static class AnnotationOrError {
final Annotation annotation;
final boolean error;
AnnotationOrError(Annotation annotation, boolean error) {
this.annotation = annotation;
this.error = error;
}
static AnnotationOrError forPossiblyNullAnnotation(Annotation annotation) {
return new AnnotationOrError(annotation, false);
}
static AnnotationOrError forError() {
return new AnnotationOrError(null, true);
}
}
private static AnnotationOrError findMapKeyAnnotation(Binder binder, Method method) {
Annotation foundAnnotation = null;
for (Annotation annotation : method.getAnnotations()) {
MapKey mapKey = annotation.annotationType().getAnnotation(MapKey.class);
if (mapKey != null) {
if (foundAnnotation != null) {
binder.addError("Found more than one MapKey annotations on %s.", method);
return AnnotationOrError.forError();
}
if (mapKey.unwrapValue()) {
try {
// validate there's a declared method called "value"
Method valueMethod = annotation.annotationType().getDeclaredMethod("value");
if (valueMethod.getReturnType().isArray()) {
binder.addError("Array types are not allowed in a MapKey with unwrapValue=true: %s",
annotation.annotationType());
return AnnotationOrError.forError();
}
} catch (NoSuchMethodException invalid) {
binder.addError("No 'value' method in MapKey with unwrapValue=true: %s",
annotation.annotationType());
return AnnotationOrError.forError();
}
}
foundAnnotation = annotation;
}
}
return AnnotationOrError.forPossiblyNullAnnotation(foundAnnotation);
}
@SuppressWarnings({"unchecked", "rawtypes"})
static TypeAndValue typeAndValueOfMapKey(Annotation mapKeyAnnotation) {
if (!mapKeyAnnotation.annotationType().getAnnotation(MapKey.class).unwrapValue()) {
return new TypeAndValue(TypeLiteral.get(mapKeyAnnotation.annotationType()), mapKeyAnnotation);
} else {
try {
Method valueMethod = mapKeyAnnotation.annotationType().getDeclaredMethod("value");
valueMethod.setAccessible(true);
TypeLiteral returnType =
TypeLiteral.get(mapKeyAnnotation.annotationType()).getReturnType(valueMethod);
return new TypeAndValue(returnType, valueMethod.invoke(mapKeyAnnotation));
} catch (NoSuchMethodException e) {
throw new IllegalStateException(e);
} catch (SecurityException e) {
throw new IllegalStateException(e);
} catch (IllegalAccessException e) {
throw new IllegalStateException(e);
} catch (InvocationTargetException e) {
throw new IllegalStateException(e);
}
}
}
private static class TypeAndValue {
final TypeLiteral type;
final T value;
TypeAndValue(TypeLiteral type, T value) {
this.type = type;
this.value = value;
}
}
}