Dynamic code loading sample

Author: wojtek-kalicinski

.gitignore

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+*.iml
+.gradle
+/local.properties
+.DS_Store
+build/
+/captures
+.externalNativeBuild
+/.idea
+/keystore.properties

.google/packaging.yaml

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+# Copyright 2019 Google LLC
+#
+# 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.
+#
+# GOOGLE SAMPLE PACKAGING DATA
+#
+# This file is used by Google as part of our samples packaging process.
+# End users may safely ignore this file. It has no relevance to other systems.
+---
+# Values: {DRAFT | PUBLISHED | INTERNAL | DEPRECATED | SUPERCEDED}
+status:       PUBLISHED
+
+# Optional, put additional explanation here for DEPRECATED or SUPERCEDED.
+# statusNote:
+
+technologies: [Android]
+categories:   [Dynamic Features]
+languages:    [Kotlin]
+solutions:    [Mobile]
+
+github:       googlesamples/android-dynamic-code-loading
+
+# Values: BEGINNER | INTERMEDIATE | ADVANCED | EXPERT
+level:        ADVANCED
+
+license: apache2

CONTRIBUTING.md

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+# How to become a contributor and submit your own code
+
+## Contributor License Agreements
+
+We'd love to accept your sample apps and patches! Before we can take them, we
+have to jump a couple of legal hurdles.
+
+Please fill out either the individual or corporate Contributor License Agreement
+(CLA).
+
+  * If you are an individual writing original source code and you're sure you
+    own the intellectual property, then you'll need to sign an [individual CLA]
+    (https://developers.google.com/open-source/cla/individual).
+  * If you work for a company that wants to allow you to contribute your work,
+    then you'll need to sign a [corporate CLA]
+    (https://developers.google.com/open-source/cla/corporate).
+
+Follow either of the two links above to access the appropriate CLA and
+instructions for how to sign and return it. Once we receive it, we'll be able to
+accept your pull requests.
+
+## Contributing A Patch
+
+1. Submit an issue describing your proposed change to the repo in question.
+1. The repo owner will respond to your issue promptly.
+1. If your proposed change is accepted, and you haven't already done so, sign a
+   Contributor License Agreement (see details above).
+1. Fork the desired repo, develop and test your code changes.
+1. Ensure that your code adheres to the existing style in the sample to which
+   you are contributing. Refer to the
+   [Google Cloud Platform Samples Style Guide]
+   (https://github.com/GoogleCloudPlatform/Template/wiki/style.html) for the
+   recommended coding standards for this organization.
+1. Ensure that your code has an appropriate set of unit tests which all pass.
+1. Submit a pull request.
+

LICENSE

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+Dynamic code loading sample
+============
+
+This sample demonstrates how to load and use classes from dynamic feature modules.
+
+Introduction
+------------
+Dynamic feature modules (DFMs) are modularized parts of your Android app. You will encounter them when you switch 
+to using Android App Bundles and want to enable on-demand or conditional feature delivery. 
+
+You can read more about app bundles at http://g.co/androidappbundle
+
+Contrary to regular library modules, DFMs depend on the base module (`com.android.application`) of your app. 
+Because of this, classes defined in DFMs are not visible from the app module at compile time and need to be accessed 
+through reflection.
+
+This sample demonstrates three different approaches to safely access code from the feature module 
+using at most 1 reflection call. 
+
+Common code is included in the `main` sourceSets, which contains the basic UI and ViewModel for this sample.
+This also contains the `StorageFeature` interface (defined in the `app` module), 
+which will be implemented in the `storage` dynamic feature module.  
+
+The other sourceSets contain code that obtains an instance of the concrete implementation from the DFM 
+using three approaches, split into the following product flavors:
+
+ `reflect/` -> uses a straight reflection call
+ `serviceLoader/` -> uses the [ServiceLoader](https://developer.android.com/reference/java/util/ServiceLoader) mechanism
+ `dagger/` -> uses Dagger 2, to enable easy instantiation of complex object graphs from the DFM
+ 
+Please note that all approaches use 1 reflect call to instantiate the `StorageFeature.Provider`, 
+although in the `serviceLoader` and `dagger` approaches they're somewhat hidden from the user.
+ 
+Additionally, when compiling the `serviceLoader` flavor using recent versions of R8, 
+the optimizer does away with dynamic class lookup and reflection, and the resulting DEX code uses direct class 
+instantiation.
+
+Pre-requisites
+--------------
+
+* Android Studio 3.4
+* Access to Play Console in order to test the on-demand features
+
+Getting Started
+---------------
+
+Use Android Studio to open the project and check out the various Build Variants available.
+
+Alternatively, build from the commandline using `./gradlew reflectDebug` 
+or `./gradlew serviceLoaderDebug` or `./gradlew daggerDebug`
+
+Support
+-------
+
+If you've found an error in this sample, please file an issue:
+https://github.com/googlesamples/android-dynamic-code-loading/issues
+
+Patches are encouraged, and may be submitted by forking this project and
+submitting a pull request through GitHub.
+
+License
+-------
+
+```
+Copyright 2019 Google LLC.
+
+Licensed to the Apache Software Foundation (ASF) under one or more contributor
+license agreements.  See the NOTICE file distributed with this work for
+additional information regarding copyright ownership.  The ASF licenses this
+file to you 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.
+```

README.md

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+/build

app/.gitignore

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+apply plugin: 'com.android.application'
+
+apply plugin: 'kotlin-android'
+apply plugin: 'kotlin-kapt'
+
+android {
+    compileSdkVersion 28
+    defaultConfig {
+        applicationId "com.google.android.samples.dynamiccodeloading"
+        minSdkVersion 21
+        targetSdkVersion 28
+        versionCode 33
+        versionName "1.0.33"
+        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
+    }
+    buildTypes {
+        debugR8 {
+            initWith(debug)
+            minifyEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+        }
+
+        release {
+            minifyEnabled true
+            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
+            signingConfig signingConfigs.debug
+        }
+    }
+
+    flavorDimensions "codeLoading"
+
+    productFlavors {
+        reflect {
+            dimension "codeLoading"
+        }
+
+        serviceLoader {
+            dimension "codeLoading"
+        }
+
+        dagger {
+            dimension "codeLoading"
+        }
+    }
+
+    dynamicFeatures = [":storage"]
+}
+
+dependencies {
+    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    api "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+    implementation "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
+
+    api 'androidx.appcompat:appcompat:1.0.2'
+    implementation 'androidx.core:core-ktx:1.0.1'
+    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
+
+    implementation "com.google.android.play:core:1.4.1"
+
+    daggerApi 'com.google.dagger:dagger:2.16'
+    api 'com.google.dagger:dagger-android-support:2.16'
+
+    kapt 'com.google.dagger:dagger-compiler:2.16'
+
+    implementation 'androidx.lifecycle:lifecycle-extensions:2.0.0'
+    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0-alpha04'
+    androidTestImplementation 'androidx.test:rules:1.2.0-alpha04'
+}

app/build.gradle

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+# Add project specific ProGuard rules here.
+# You can control the set of applied configuration files using the
+# proguardFiles setting in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}
+
+# Uncomment this to preserve the line number information for
+# debugging stack traces.
+-keepattributes SourceFile,LineNumberTable
+#-keepattributes *Annotation*
+#
+
+# If you keep the line number information, uncomment this to
+# hide the original source file name.
+#-renamesourcefileattribute SourceFile
+
+
+-keep class com.google.android.samples.storage.StorageFeatureImpl {
+    com.google.android.samples.storage.StorageFeatureImpl$Provider Provider;
+}
+
+-keep class com.google.android.samples.storage.StorageFeatureImpl$Provider {
+    *;
+}
+
+# There was a bug, but it's gone now. Uncomment on earlier R8 versions (?)
+#-keep interface com.google.android.samples.dynamiccodeloading.StorageFeature {
+#    *;
+#}
+
+-keep class kotlin.Metadata {
+    *;
+}

app/proguard-rules.pro

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+/*
+ * Copyright 2019 Google LLC
+ *
+ * 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.android.samples.dynamiccodeloading
+
+import android.preference.PreferenceManager
+import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.action.ViewActions.click
+import androidx.test.espresso.assertion.ViewAssertions.matches
+import androidx.test.espresso.matcher.ViewMatchers.withId
+import androidx.test.espresso.matcher.ViewMatchers.withText
+import androidx.test.filters.LargeTest
+import androidx.test.platform.app.InstrumentationRegistry
+import androidx.test.rule.ActivityTestRule
+import org.junit.Before
+import org.junit.Rule
+import org.junit.Test
+
+
+@LargeTest
+class MainActivityTest {
+
+    @Rule
+    @JvmField
+    var mActivityTestRule = ActivityTestRule(MainActivity::class.java, false, false)
+
+
+    /**
+     * Clear sharedpreferences before each run
+     */
+    @Before
+    fun before() {
+        PreferenceManager.getDefaultSharedPreferences(
+            InstrumentationRegistry.getInstrumentation().getTargetContext().applicationContext
+        ).edit().clear().commit()
+    }
+
+    /**
+     * This is an (overly) simplified test that can be used locally with all APK splits installed.
+     * It doesn't test Play Core APIs (on-demand delivery) since this is impossible without going through the Play Store
+     */
+    @Test
+    fun mainActivityTest() {
+        mActivityTestRule.launchActivity(null)
+        val appCompatButton = onView(withId(R.id.incrementButton))
+        appCompatButton.perform(click())
+        appCompatButton.perform(click())
+        appCompatButton.perform(click())
+
+        onView(withId(R.id.saveButton)).perform(click())
+
+        InstrumentationRegistry.getInstrumentation().runOnMainSync(Runnable { mActivityTestRule.activity.recreate() })
+
+        val textView = onView(withId(R.id.counterText))
+        textView.check(matches(withText("3")))
+    }
+}

app/src/androidTest/java/com/google/android/samples/dynamiccodeloading/MainActivityTest.kt

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+<?xml version="1.0" encoding="utf-8"?><!--
+  ~ Copyright 2019 Google LLC
+  ~
+  ~ 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.
+  ~
+  -->
+<manifest xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools"
+          package="com.google.android.samples.dynamiccodeloading">
+
+    <application
+            tools:replace="android:name"
+            android:name=".MyApplication"
+            tools:ignore="AllowBackup,GoogleAppIndexingWarning"/>
+
+</manifest>