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Java example source code file (DaggerMethodScanner.java)

This example Java source code file (DaggerMethodScanner.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

annotation, daggermethodscanner, elementsintoset, guice, injectionpoint, instance, key, map, moduleannotatedmethodscanner, multibinder, override, provides, reflection, set, set_values, unknown, util

The DaggerMethodScanner.java Java example source code

 * 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,
 * See the License for the specific language governing permissions and
 * limitations under the License.
package com.google.inject.daggeradapter;

import com.google.common.collect.ImmutableSet;
import com.google.inject.Binder;
import com.google.inject.Key;
import com.google.inject.internal.UniqueAnnotations;
import com.google.inject.multibindings.Multibinder;
import com.google.inject.spi.InjectionPoint;
import com.google.inject.spi.ModuleAnnotatedMethodScanner;

import dagger.Provides;
import dagger.multibindings.IntoSet;
import dagger.multibindings.ElementsIntoSet;
import dagger.multibindings.IntoMap;
import dagger.Provides.Type;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.Set;

 * A scanner to process provider methods on Dagger modules.
 * @author cgruber@google.com (Christian Gruber)
final class DaggerMethodScanner extends ModuleAnnotatedMethodScanner {
  static DaggerMethodScanner INSTANCE = new DaggerMethodScanner();

  @Override public Set<? extends Class annotationClasses() {
    return ImmutableSet.of(dagger.Provides.class);

  @Override public <T> Key prepareMethod(
      Binder binder, Annotation rawAnnotation, Key<T> key, InjectionPoint injectionPoint) {
    Method providesMethod = (Method) injectionPoint.getMember();
    Provides annotation = (Provides) rawAnnotation;
    if (providesMethod.isAnnotationPresent(IntoSet.class)) {
      return processSetBinding(binder, key);
    } else if (providesMethod.isAnnotationPresent(ElementsIntoSet.class)) {
      binder.addError("@ElementsIntoSet contributions are not suppored by Guice.", providesMethod);
      return key;
    } else if (providesMethod.isAnnotationPresent(IntoMap.class)) {
      /* TODO(cgruber) implement map bindings */
      binder.addError("Map bindings are not yet supported.");
      return key;

    switch (annotation.type()) {
      case UNIQUE:
        return key;
      case MAP:
        /* TODO(cgruber) implement map bindings */
        binder.addError("Map bindings are not yet supported.");
        return key;
      case SET:
        return processSetBinding(binder, key);
      case SET_VALUES:
        binder.addError(Type.SET_VALUES.name() + " contributions are not supported by Guice.",
        return key;
        binder.addError("Unknown @Provides type " + annotation.type() + ".", providesMethod);
        return key;

  private static <T> Key processSetBinding(Binder binder, Key key) {
    Multibinder<T> setBinder = Multibinder.newSetBinder(binder, key.getTypeLiteral());
    Key<T> newKey = Key.get(key.getTypeLiteral(), UniqueAnnotations.create());
    return newKey;

  private DaggerMethodScanner() {}

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