/*
 * Copyright (C) 2007 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.util;

import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.base.Objects;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Sets;
import com.google.inject.Inject;
import com.google.inject.Injector;
import com.google.inject.Provider;
import com.google.inject.spi.Dependency;
import com.google.inject.spi.InjectionPoint;
import com.google.inject.spi.ProviderWithDependencies;
import java.util.Set;

Static utility methods for creating and working with instances of Provider.
Author:Kevin Bourrillion (kevinb9n@gmail.com)
Since:2.0
/** * Static utility methods for creating and working with instances of {@link Provider}. * * @author Kevin Bourrillion (kevinb9n@gmail.com) * @since 2.0 */
public final class Providers { private Providers() {}
Returns a provider which always provides instance. This should not be necessary to use in your application, but is helpful for several types of unit tests.
Params:
  • instance – the instance that should always be provided. This is also permitted to be null, to enable aggressive testing, although in real life a Guice-supplied Provider will never return null.
/** * Returns a provider which always provides {@code instance}. This should not be necessary to use * in your application, but is helpful for several types of unit tests. * * @param instance the instance that should always be provided. This is also permitted to be null, * to enable aggressive testing, although in real life a Guice-supplied Provider will never * return null. */
public static <T> Provider<T> of(final T instance) { return new ConstantProvider<T>(instance); } private static final class ConstantProvider<T> implements Provider<T> { private final T instance; private ConstantProvider(T instance) { this.instance = instance; } @Override public T get() { return instance; } @Override public String toString() { return "of(" + instance + ")"; } @Override public boolean equals(Object obj) { return (obj instanceof ConstantProvider) && Objects.equal(instance, ((ConstantProvider<?>) obj).instance); } @Override public int hashCode() { return Objects.hashCode(instance); } }
Returns a Guice-friendly com.google.inject.Provider for the given JSR-330 javax.inject.Provider. The converse method is unnecessary, since Guice providers directly implement the JSR-330 interface.
Since:3.0
/** * Returns a Guice-friendly {@code com.google.inject.Provider} for the given JSR-330 {@code * javax.inject.Provider}. The converse method is unnecessary, since Guice providers directly * implement the JSR-330 interface. * * @since 3.0 */
public static <T> Provider<T> guicify(javax.inject.Provider<T> provider) { if (provider instanceof Provider) { return (Provider<T>) provider; } final javax.inject.Provider<T> delegate = checkNotNull(provider, "provider"); // Ensure that we inject all injection points from the delegate provider. Set<InjectionPoint> injectionPoints = InjectionPoint.forInstanceMethodsAndFields(provider.getClass()); if (injectionPoints.isEmpty()) { return new GuicifiedProvider<T>(delegate); } else { Set<Dependency<?>> mutableDeps = Sets.newHashSet(); for (InjectionPoint ip : injectionPoints) { mutableDeps.addAll(ip.getDependencies()); } final Set<Dependency<?>> dependencies = ImmutableSet.copyOf(mutableDeps); return new GuicifiedProviderWithDependencies<T>(dependencies, delegate); } } private static class GuicifiedProvider<T> implements Provider<T> { protected final javax.inject.Provider<T> delegate; private GuicifiedProvider(javax.inject.Provider<T> delegate) { this.delegate = delegate; } @Override public T get() { return delegate.get(); } @Override public String toString() { return "guicified(" + delegate + ")"; } @Override public boolean equals(Object obj) { return (obj instanceof GuicifiedProvider) && Objects.equal(delegate, ((GuicifiedProvider<?>) obj).delegate); } @Override public int hashCode() { return Objects.hashCode(delegate); } } private static final class GuicifiedProviderWithDependencies<T> extends GuicifiedProvider<T> implements ProviderWithDependencies<T> { private final Set<Dependency<?>> dependencies; private GuicifiedProviderWithDependencies( Set<Dependency<?>> dependencies, javax.inject.Provider<T> delegate) { super(delegate); this.dependencies = dependencies; } @SuppressWarnings("unused") @Inject void initialize(Injector injector) { injector.injectMembers(delegate); } @Override public Set<Dependency<?>> getDependencies() { return dependencies; } } }