Add a base activity for React Native apps. Fixes #4043

Summary:
Having a base activity allows us to add new features and fixes without having to change the generated `MainActivity` file.

cc mkonicek arbesfeld
Closes https://github.com/facebook/react-native/pull/4827

Reviewed By: bestander

Differential Revision: D2783527

Pulled By: mkonicek

fb-gh-sync-id: 707b82839809ca2e1775f5d3ac022a6d00bcac5a

ReactAndroid/src/main/java/com/facebook/react/ReactActivity.java

@@ -0,0 +1,215 @@
+package com.facebook.react;
+
+import android.app.Activity;
+import android.content.Intent;
+import android.os.Build;
+import android.os.Bundle;
+import android.os.Handler;
+import android.provider.Settings;
+import android.view.KeyEvent;
+import android.widget.EditText;
+import android.widget.Toast;
+
+import com.facebook.common.logging.FLog;
+import com.facebook.react.common.ReactConstants;
+import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler;
+
+import java.util.List;
+
+import javax.annotation.Nullable;
+
+/**
+ * Base Activity for React Native applications.
+ */
+public abstract class ReactActivity extends Activity implements DefaultHardwareBackBtnHandler {
+
+  private static final String REDBOX_PERMISSION_MESSAGE =
+      "Overlay permissions needs to be granted in order for react native apps to run in dev mode";
+
+  private @Nullable ReactInstanceManager mReactInstanceManager;
+  private LifecycleState mLifecycleState = LifecycleState.BEFORE_RESUME;
+  private boolean mDoRefresh = false;
+
+  /**
+   * Returns the name of the bundle in assets. If this is null, and no file path is specified for
+   * the bundle, the app will only work with {@code getUseDeveloperSupport} enabled and will
+   * always try to load the JS bundle from the packager server.
+   * e.g. "index.android.bundle"
+   */
+  protected @Nullable String getBundleAssetName() {
+    return "index.android.bundle";
+  };
+
+  /**
+   * Returns a custom path of the bundle file. This is used in cases the bundle should be loaded
+   * from a custom path. By default it is loaded from Android assets, from a path specified
+   * by {@link getBundleAssetName}.
+   * e.g. "file://sdcard/myapp_cache/index.android.bundle"
+   */
+  protected @Nullable String getJSBundleFile() {
+    return null;
+  }
+
+  /**
+   * Returns the name of the main module. Determines the URL used to fetch the JS bundle
+   * from the packager server. It is only used when dev support is enabled.
+   * This is the first file to be executed once the {@link ReactInstanceManager} is created.
+   * e.g. "index.android"
+   */
+  protected String getJSMainModuleName() {
+    return "index.android";
+  }
+
+  /**
+   * Returns the name of the main component registered from JavaScript.
+   * This is used to schedule rendering of the component.
+   * e.g. "MoviesApp"
+   */
+  protected abstract String getMainComponentName();
+
+  /**
+   * Returns whether dev mode should be enabled. This enables e.g. the dev menu.
+   */
+  protected abstract boolean getUseDeveloperSupport();
+
+  /**
+   * Returns a list of {@link ReactPackage} used by the app.
+   * You'll most likely want to return at least the {@code MainReactPackage}.
+   * If your app uses additional views or modules besides the default ones,
+   * you'll want to include more packages here.
+   */
+  protected abstract List<ReactPackage> getPackages();
+
+  /**
+   * A subclass may override this method if it needs to use a custom instance.
+   */
+  protected ReactInstanceManager createReactInstanceManager() {
+    ReactInstanceManager.Builder builder = ReactInstanceManager.builder()
+        .setApplication(getApplication())
+        .setJSMainModuleName(getJSMainModuleName())
+        .setUseDeveloperSupport(getUseDeveloperSupport())
+        .setInitialLifecycleState(mLifecycleState);
+
+    for (ReactPackage reactPackage : getPackages()) {
+      builder.addPackage(reactPackage);
+    }
+
+    String jsBundleFile = getJSBundleFile();
+
+    if (jsBundleFile != null) {
+      builder.setJSBundleFile(jsBundleFile);
+    } else {
+      builder.setBundleAssetName(getBundleAssetName());
+    }
+
+    return builder.build();
+  }
+
+  /**
+   * A subclass may override this method if it needs to use a custom {@link ReactRootView}.
+   */
+  protected ReactRootView createRootView() {
+    return new ReactRootView(this);
+  }
+
+  @Override
+  protected void onCreate(Bundle savedInstanceState) {
+    super.onCreate(savedInstanceState);
+
+    if (getUseDeveloperSupport() && Build.VERSION.SDK_INT >= 23) {
+      // Get permission to show redbox in dev builds.
+      if (!Settings.canDrawOverlays(this)) {
+        Intent serviceIntent = new Intent(Settings.ACTION_MANAGE_OVERLAY_PERMISSION);
+        startActivity(serviceIntent);
+        FLog.w(ReactConstants.TAG, REDBOX_PERMISSION_MESSAGE);
+        Toast.makeText(this, REDBOX_PERMISSION_MESSAGE, Toast.LENGTH_LONG).show();
+      }
+    }
+
+    mReactInstanceManager = createReactInstanceManager();
+    ReactRootView mReactRootView = createRootView();
+    mReactRootView.startReactApplication(mReactInstanceManager, getMainComponentName());
+    setContentView(mReactRootView);
+  }
+
+  @Override
+  protected void onPause() {
+    super.onPause();
+
+    mLifecycleState = LifecycleState.BEFORE_RESUME;
+
+    if (mReactInstanceManager != null) {
+      mReactInstanceManager.onPause();
+    }
+  }
+
+  @Override
+  protected void onResume() {
+    super.onResume();
+
+    mLifecycleState = LifecycleState.RESUMED;
+
+    if (mReactInstanceManager != null) {
+      mReactInstanceManager.onResume(this, this);
+    }
+  }
+
+  @Override
+  protected void onDestroy() {
+    super.onDestroy();
+
+    if (mReactInstanceManager != null) {
+      mReactInstanceManager.onDestroy();
+    }
+  }
+
+  @Override
+  public void onActivityResult(int requestCode, int resultCode, Intent data) {
+    if (mReactInstanceManager != null) {
+      mReactInstanceManager.onActivityResult(requestCode, resultCode, data);
+    }
+  }
+
+  @Override
+  public boolean onKeyUp(int keyCode, KeyEvent event) {
+    if (mReactInstanceManager != null &&
+        mReactInstanceManager.getDevSupportManager().getDevSupportEnabled()) {
+      if (keyCode == KeyEvent.KEYCODE_MENU) {
+        mReactInstanceManager.showDevOptionsDialog();
+        return true;
+      }
+      if (keyCode == KeyEvent.KEYCODE_R && !(getCurrentFocus() instanceof EditText)) {
+        // Enable double-tap-R-to-reload
+        if (mDoRefresh) {
+          mReactInstanceManager.getDevSupportManager().handleReloadJS();
+          mDoRefresh = false;
+        } else {
+          mDoRefresh = true;
+          new Handler().postDelayed(
+              new Runnable() {
+                @Override
+                public void run() {
+                  mDoRefresh = false;
+                }
+              },
+              200);
+        }
+      }
+    }
+    return super.onKeyUp(keyCode, event);
+  }
+
+  @Override
+  public void onBackPressed() {
+    if (mReactInstanceManager != null) {
+      mReactInstanceManager.onBackPressed();
+    } else {
+      super.onBackPressed();
+    }
+  }
+
+  @Override
+  public void invokeDefaultOnBackPressed() {
+    super.onBackPressed();
+  }
+}

local-cli/generator-android/templates/package/MainActivity.java

@@ -1,78 +1,35 @@
 package <%= package %>;
 
-import android.app.Activity;
+import com.facebook.react.ReactActivity;
-import android.os.Bundle;
-import android.view.KeyEvent;
-
-import com.facebook.react.LifecycleState;
-import com.facebook.react.ReactInstanceManager;
-import com.facebook.react.ReactRootView;
-import com.facebook.react.modules.core.DefaultHardwareBackBtnHandler;
 import com.facebook.react.shell.MainReactPackage;
-import com.facebook.soloader.SoLoader;
 
-public class MainActivity extends Activity implements DefaultHardwareBackBtnHandler {
+public class MainActivity extends ReactActivity {
-
-    private ReactInstanceManager mReactInstanceManager;
-    private ReactRootView mReactRootView;
 
+    /**
+     * Returns the name of the main component registered from JavaScript.
+     * This is used to schedule rendering of the component.
+     */
     @Override
-    protected void onCreate(Bundle savedInstanceState) {
+    protected String getMainComponentName() {
-        super.onCreate(savedInstanceState);
+        return "<%= name %>";
-        mReactRootView = new ReactRootView(this);
-
-        mReactInstanceManager = ReactInstanceManager.builder()
-                .setApplication(getApplication())
-                .setBundleAssetName("index.android.bundle")
-                .setJSMainModuleName("index.android")
-                .addPackage(new MainReactPackage())
-                .setUseDeveloperSupport(BuildConfig.DEBUG)
-                .setInitialLifecycleState(LifecycleState.RESUMED)
-                .build();
-
-        mReactRootView.startReactApplication(mReactInstanceManager, "<%= name %>", null);
-
-        setContentView(mReactRootView);
     }
 
+    /**
+     * Returns whether dev mode should be enabled.
+     * This enables e.g. the dev menu.
+     */
     @Override
-    public boolean onKeyUp(int keyCode, KeyEvent event) {
+    protected boolean getUseDeveloperSupport() {
-        if (keyCode == KeyEvent.KEYCODE_MENU && mReactInstanceManager != null) {
+        return BuildConfig.DEBUG;
-            mReactInstanceManager.showDevOptionsDialog();
-            return true;
-        }
-        return super.onKeyUp(keyCode, event);
     }
 
+   /**
+   * A list of packages used by the app. If the app uses additional views
+   * or modules besides the default ones, add more packages here.
+   */
     @Override
-    public void onBackPressed() {
+    protected abstract List<ReactPackage> getPackages() {
-      if (mReactInstanceManager != null) {
+      return Arrays.<ReactPackage>asList(
-        mReactInstanceManager.onBackPressed();
+        new MainReactPackage());
-      } else {
-        super.onBackPressed();
-      }
-    }
-
-    @Override
-    public void invokeDefaultOnBackPressed() {
-      super.onBackPressed();
-    }
-
-    @Override
-    protected void onPause() {
-        super.onPause();
-
-        if (mReactInstanceManager != null) {
-            mReactInstanceManager.onPause();
-        }
-    }
-
-    @Override
-    protected void onResume() {
-        super.onResume();
-
-        if (mReactInstanceManager != null) {
-            mReactInstanceManager.onResume(this, this);
-        }
     }
 }