dagger.android.support.AndroidSupportInjection.java Source code

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Here is the source code for dagger.android.support.AndroidSupportInjection.java

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/*
 * Copyright (C) 2017 The Dagger Authors.
 *
 * 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 dagger.android.support;

import static dagger.internal.Preconditions.checkNotNull;

import android.app.Activity;
import android.support.v4.app.Fragment;
import android.util.Log;
import dagger.android.AndroidInjector;
import dagger.internal.Beta;
import dagger.internal.Preconditions;

/** Injects core Android types from support libraries. */
@Beta
public final class AndroidSupportInjection {
    private static final String TAG = "dagger.android.support";

    /**
     * Injects {@code fragment} if an associated {@link dagger.android.AndroidInjector} implementation
     * can be found, otherwise throws an {@link IllegalArgumentException}.
     *
     * <p>Uses the following algorithm to find the appropriate {@code AndroidInjector<Fragment>} to
     * use to inject {@code fragment}:
     *
     * <ol>
     *   <li>Walks the parent-fragment hierarchy to find the a fragment that implements {@link
     *       HasSupportFragmentInjector}, and if none do
     *   <li>Uses the {@code fragment}'s {@link Fragment#getActivity() activity} if it implements
     *       {@link HasSupportFragmentInjector}, and if not
     *   <li>Uses the {@link android.app.Application} if it implements {@link
     *       HasSupportFragmentInjector}.
     * </ol>
     *
     * If none of them implement {@link HasSupportFragmentInjector}, a {@link
     * IllegalArgumentException} is thrown.
     *
     * @throws IllegalArgumentException if no parent fragment, activity, or application implements
     *     {@link HasSupportFragmentInjector}.
     */
    public static void inject(Fragment fragment) {
        Preconditions.checkNotNull(fragment, "fragment");
        HasSupportFragmentInjector hasSupportFragmentInjector = findHasFragmentInjector(fragment);
        Log.d(TAG, String.format("An injector for %s was found in %s", fragment.getClass().getCanonicalName(),
                hasSupportFragmentInjector.getClass().getCanonicalName()));

        AndroidInjector<Fragment> fragmentInjector = hasSupportFragmentInjector.supportFragmentInjector();
        Preconditions.checkNotNull(fragmentInjector, "%s.supportFragmentInjector() returned null",
                hasSupportFragmentInjector.getClass().getCanonicalName());

        fragmentInjector.inject(fragment);
    }

    private static HasSupportFragmentInjector findHasFragmentInjector(Fragment fragment) {
        Fragment parentFragment = fragment;
        while ((parentFragment = parentFragment.getParentFragment()) != null) {
            if (parentFragment instanceof HasSupportFragmentInjector) {
                return (HasSupportFragmentInjector) parentFragment;
            }
        }
        Activity activity = fragment.getActivity();
        if (activity instanceof HasSupportFragmentInjector) {
            return (HasSupportFragmentInjector) activity;
        }
        if (activity.getApplication() instanceof HasSupportFragmentInjector) {
            return (HasSupportFragmentInjector) activity.getApplication();
        }
        throw new IllegalArgumentException(
                String.format("No injector was found for %s", fragment.getClass().getCanonicalName()));
    }

    private AndroidSupportInjection() {
    }
}