Simplify the template for New Architecture using the .defaults package

Summary:
This commit simplifies the new app template by encapsulating a lot of configuration
by using the `DefaultReactNativeHost` from the .defaults package.

This should work for most of the users while still allowing advanced use cases
by using the good old ReactNativeHost.

Changelog:
[Android] [Changed] - Simplify the template for New Architecture using the .defaults package

Differential Revision: D38820111

fbshipit-source-id: d85969d12ecf8012bf526f73c4f680b031392c4a

template/android/app/build.gradle

@@ -129,6 +129,13 @@ def reactNativeArchitectures() {
     return value ? value.split(",") : ["armeabi-v7a", "x86", "x86_64", "arm64-v8a"]
 }
 
+/**
+ * The name of the dynamic library for this application. This will contain all the
+ * compiled C++ code and will be loaded at runtime.
+ * The default is "appmodules" so that we'll have a `libappmodules.so` to load.
+ */
+def dynamicLibraryName = "appmodules"
+
 android {
     ndkVersion rootProject.ext.ndkVersion
 
@@ -141,6 +148,7 @@ android {
         versionCode 1
         versionName "1.0"
         buildConfigField "boolean", "IS_NEW_ARCHITECTURE_ENABLED", isNewArchitectureEnabled().toString()
+        buildConfigField "String", "DYNAMIC_LIBRARY_NAME", "\"$dynamicLibraryName\""
 
         if (isNewArchitectureEnabled()) {
             // We configure the CMake build only if you decide to opt-in for the New Architecture.
@@ -150,6 +158,7 @@ android {
                         "-DREACT_ANDROID_DIR=$rootDir/../node_modules/react-native/ReactAndroid",
                         "-DREACT_ANDROID_BUILD_DIR=$rootDir/../node_modules/react-native/ReactAndroid/build",
                         "-DNODE_MODULES_DIR=$rootDir/../node_modules",
+                        "-DTARGET_NAME=$dynamicLibraryName",
                         "-DANDROID_STL=c++_shared"
                 }
             }

template/android/app/src/main/java/com/helloworld/MainApplication.java

@@ -6,14 +6,14 @@
 import com.facebook.react.ReactNativeHost;
 import com.facebook.react.ReactPackage;
 import com.facebook.react.config.ReactFeatureFlags;
+import com.facebook.react.defaults.DefaultReactNativeHost;
 import com.facebook.soloader.SoLoader;
-import com.helloworld.newarchitecture.MainApplicationReactNativeHost;
 import java.util.List;
 
 public class MainApplication extends Application implements ReactApplication {
 
   private final ReactNativeHost mReactNativeHost =
-      new ReactNativeHost(this) {
+      new DefaultReactNativeHost(this) {
         @Override
         public boolean getUseDeveloperSupport() {
           return BuildConfig.DEBUG;
@@ -32,26 +32,35 @@ protected List<ReactPackage> getPackages() {
         protected String getJSMainModuleName() {
           return "index";
         }
-      };
 
-  private final ReactNativeHost mNewArchitectureNativeHost =
-      new MainApplicationReactNativeHost(this);
+        @Override
+        public String getDynamicLibraryName() {
+          // If you enabled the New Architecture, you need to return the name of the
+          // dynamic library to load (usually 'appmodule'). This is configured
+          // in your build.gradle file.
+          if (BuildConfig.IS_NEW_ARCHITECTURE_ENABLED) {
+            return BuildConfig.DYNAMIC_LIBRARY_NAME;
+          } else {
+            return null;
+          }
+        }
+      };
 
   @Override
   public ReactNativeHost getReactNativeHost() {
-    if (BuildConfig.IS_NEW_ARCHITECTURE_ENABLED) {
-      return mNewArchitectureNativeHost;
-    } else {
-      return mReactNativeHost;
-    }
+    return mReactNativeHost;
   }
 
   @Override
   public void onCreate() {
     super.onCreate();
-    // If you opted-in for the New Architecture, we enable the TurboModule system
-    ReactFeatureFlags.useTurboModules = BuildConfig.IS_NEW_ARCHITECTURE_ENABLED;
     SoLoader.init(this, /* native exopackage */ false);
+    if (BuildConfig.IS_NEW_ARCHITECTURE_ENABLED) {
+      // If you opted-in for the New Architecture, we enable the TurboModule system
+      // and load the native dynamic library for this app.
+      ReactFeatureFlags.useTurboModules = true;
+      SoLoader.loadLibrary(BuildConfig.DYNAMIC_LIBRARY_NAME);
+    }
     ReactNativeFlipper.initializeFlipper(this, getReactNativeHost().getReactInstanceManager());
   }
 }

template/android/app/src/main/jni/CMakeLists.txt

@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.13)
 
 # Define the library name here.
-project(helloworld_appmodules)
+project(${TARGET_NAME})
 
 # This file includes all the necessary to let you build your application with the New Architecture.
 include(${REACT_ANDROID_DIR}/cmake-utils/ReactNative-application.cmake)

template/android/app/src/main/jni/MainApplicationTurboModuleManagerDelegate.cpp

@@ -35,11 +35,5 @@ MainApplicationTurboModuleManagerDelegate::getTurboModule(
   return MainApplicationModuleProvider(name, params);
 }
 
-bool MainApplicationTurboModuleManagerDelegate::canCreateTurboModule(
-    const std::string &name) {
-  return getTurboModule(name, nullptr) != nullptr ||
-      getTurboModule(name, {.moduleName = name}) != nullptr;
-}
-
 } // namespace react
 } // namespace facebook

template/android/app/src/main/jni/MainApplicationTurboModuleManagerDelegate.h

@@ -14,7 +14,7 @@ class MainApplicationTurboModuleManagerDelegate
  public:
   // Adapt it to the package you used for your Java class.
   static constexpr auto kJavaDescriptor =
-      "Lcom/helloworld/newarchitecture/modules/MainApplicationTurboModuleManagerDelegate;";
+      "Lcom/facebook/react/defaults/DefaultTurboModuleManagerDelegate;";
 
   static jni::local_ref<jhybriddata> initHybrid(jni::alias_ref<jhybridobject>);
 
@@ -26,12 +26,6 @@ class MainApplicationTurboModuleManagerDelegate
   std::shared_ptr<TurboModule> getTurboModule(
       const std::string &name,
       const JavaTurboModule::InitParams &params) override;
-
-  /**
-   * Test-only method. Allows user to verify whether a TurboModule can be
-   * created by instances of this class.
-   */
-  bool canCreateTurboModule(const std::string &name);
 };
 
 } // namespace react

template/android/app/src/main/jni/MainComponentsRegistry.h

@@ -13,7 +13,7 @@ class MainComponentsRegistry
  public:
   // Adapt it to the package you used for your Java class.
   constexpr static auto kJavaDescriptor =
-      "Lcom/helloworld/newarchitecture/components/MainComponentsRegistry;";
+      "Lcom/facebook/react/defaults/DefaultComponentsRegistry;";
 
   static void registerNatives();