Allow developers to load JavaScript bundle from any source.

Summary: This patch adds two pieces of functionality:

- Exposes `JSBundleLoader` to allow a developer to load JavaScript bundles as they choose.
- Adds `ReactBridge.loadScripFromFile` method which loads a JavaScript bundle from an arbitrary file path.

Example usage:

```
JSBundleLoader jsBundleLoader = new JSBundleLoader() {
    Override
    public void loadScript(ReactBridge reactBridge) {
        reactBridge.loadScriptFromFile("/sdcard/Download/index.android.bundle");
    }
};

mReactInstanceManager = ReactInstanceManager.builder()
        .setApplication(getApplication())
        .setJSBundleLoader(jsBundleLoader)
        .setJSMainModuleName("") /* necessary due to TODO(6803830) */
        .addPackage(new MainReactPackage())
        .setInitialLifecycleState(LifecycleState.RESUMED)
        .build();
```

cc ide
Closes https://github.com/facebook/react-native/pull/3189

Reviewed By: svcscm

Differential Revision: D2535819

Pulled By: mkonicek

fb-gh-sync-id: f319299dbe29bab3b7e91f94249c14b270d9fec3

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

@@ -77,7 +77,7 @@ public class ReactInstanceManager {
   private @Nullable ReactContextInitParams mPendingReactContextInitParams;
 
   /* accessed from any thread */
-  private final @Nullable String mBundleAssetName; /* name of JS bundle file in assets folder */
+  private @Nullable String mJSBundleFile; /* path to JS bundle on file system */
   private final @Nullable String mJSMainModuleName; /* path to JS bundle root on packager server */
   private final List<ReactPackage> mPackages;
   private final DevSupportManager mDevSupportManager;
@@ -176,7 +176,7 @@ public class ReactInstanceManager {
 
   private ReactInstanceManager(
       Context applicationContext,
-      @Nullable String bundleAssetName,
+      @Nullable String jsBundleFile,
       @Nullable String jsMainModuleName,
       List<ReactPackage> packages,
       boolean useDeveloperSupport,
@@ -185,7 +185,7 @@ public class ReactInstanceManager {
     initializeSoLoaderIfNecessary(applicationContext);
 
     mApplicationContext = applicationContext;
-    mBundleAssetName = bundleAssetName;
+    mJSBundleFile = jsBundleFile;
     mJSMainModuleName = jsMainModuleName;
     mPackages = packages;
     mUseDeveloperSupport = useDeveloperSupport;
@@ -224,30 +224,29 @@ public class ReactInstanceManager {
     SoLoader.init(applicationContext, /* native exopackage */ false);
   }
 
+  public void setJSBundleFile(String jsBundleFile) {
+    mJSBundleFile = jsBundleFile;
+  }
+
   /**
    * Trigger react context initialization asynchronously in a background async task. This enables
    * applications to pre-load the application JS, and execute global code before
    * {@link ReactRootView} is available and measured.
    */
   public void createReactContextInBackground() {
-    if (mUseDeveloperSupport) {
+    if (mUseDeveloperSupport && mJSMainModuleName != null) {
       if (mDevSupportManager.hasUpToDateJSBundleInCache()) {
         // If there is a up-to-date bundle downloaded from server, always use that
         onJSBundleLoadedFromServer();
-        return;
-      } else if (mBundleAssetName == null ||
-          !mDevSupportManager.hasBundleInAssets(mBundleAssetName)) {
-        // Bundle not available in assets, fetch from the server
+      } else {
         mDevSupportManager.handleReloadJS();
-        return;
       }
+      return;
     }
-    // Use JS file from assets
+
     recreateReactContextInBackground(
         new JSCJavaScriptExecutor(),
-        JSBundleLoader.createAssetLoader(
-            mApplicationContext.getAssets(),
-            mBundleAssetName));
+        JSBundleLoader.createFileLoader(mApplicationContext, mJSBundleFile));
   }
 
   /**
@@ -564,7 +563,7 @@ public class ReactInstanceManager {
 
     private final List<ReactPackage> mPackages = new ArrayList<>();
 
-    private @Nullable String mBundleAssetName;
+    private @Nullable String mJSBundleFile;
     private @Nullable String mJSMainModuleName;
     private @Nullable NotThreadSafeBridgeIdleDebugListener mBridgeIdleDebugListener;
     private @Nullable Application mApplication;
@@ -575,11 +574,21 @@ public class ReactInstanceManager {
     }
 
     /**
-     * Name of the JS budle file to be loaded from application's raw assets.
+     * Name of the JS bundle file to be loaded from application's raw assets.
+     *
      * Example: {@code "index.android.js"}
      */
     public Builder setBundleAssetName(String bundleAssetName) {
-      mBundleAssetName = bundleAssetName;
+      return this.setJSBundleFile("assets://" + bundleAssetName);
+    }
+
+    /**
+     * Path to the JS bundle file to be loaded from the file system.
+     *
+     * Example: {@code "assets://index.android.js" or "/sdcard/main.jsbundle}
+     */
+    public Builder setJSBundleFile(String jsBundleFile) {
+      mJSBundleFile = jsBundleFile;
       return this;
     }
 
@@ -639,21 +648,23 @@ public class ReactInstanceManager {
      * Before calling {@code build}, the following must be called:
      * <ul>
      * <li> {@link #setApplication}
-     * <li> {@link #setBundleAssetName} or {@link #setJSMainModuleName}
+     * <li> {@link #setJSBundleFile} or {@link #setJSMainModuleName}
      * </ul>
      */
     public ReactInstanceManager build() {
       Assertions.assertCondition(
-          mUseDeveloperSupport || mBundleAssetName != null,
-          "JS Bundle has to be provided in app assets when dev support is disabled");
+          mUseDeveloperSupport || mJSBundleFile != null,
+          "JS Bundle File has to be provided when dev support is disabled");
+
       Assertions.assertCondition(
-          mBundleAssetName != null || mJSMainModuleName != null,
-          "Either BundleAssetName or MainModuleName needs to be provided");
+          mJSMainModuleName != null || mJSBundleFile != null,
+          "Either MainModuleName or JS Bundle File needs to be provided");
+
       return new ReactInstanceManager(
           Assertions.assertNotNull(
               mApplication,
               "Application property has not been set with this builder"),
-          mBundleAssetName,
+          mJSBundleFile,
           mJSMainModuleName,
           mPackages,
           mUseDeveloperSupport,

ReactAndroid/src/main/java/com/facebook/react/bridge/JSBundleLoader.java

@@ -9,7 +9,7 @@
 
 package com.facebook.react.bridge;
 
-import android.content.res.AssetManager;
+import android.content.Context;
 
 /**
  * A class that stores JS bundle information and allows {@link CatalystInstance} to load a correct
@@ -22,18 +22,22 @@ public abstract class JSBundleLoader {
    * should be used. JS bundle will be read from assets directory in native code to save on passing
    * large strings from java to native memory.
    */
-  public static JSBundleLoader createAssetLoader(
-      final AssetManager assetManager,
-      final String assetFileName) {
+  public static JSBundleLoader createFileLoader(
+      final Context context,
+      final String fileName) {
     return new JSBundleLoader() {
       @Override
       public void loadScript(ReactBridge bridge) {
-        bridge.loadScriptFromAssets(assetManager, assetFileName);
+        if (fileName.startsWith("assets://")) {
+          bridge.loadScriptFromAssets(context.getAssets(), fileName.replaceFirst("assets://", ""));
+        } else {
+          bridge.loadScriptFromFile(fileName, fileName);
+        }
       }
 
       @Override
       public String getSourceUrl() {
-        return "file:///android_asset/" + assetFileName;
+        return fileName;
       }
     };
   }
@@ -51,7 +55,7 @@ public abstract class JSBundleLoader {
     return new JSBundleLoader() {
       @Override
       public void loadScript(ReactBridge bridge) {
-        bridge.loadScriptFromNetworkCached(sourceURL, cachedFileLocation);
+        bridge.loadScriptFromFile(cachedFileLocation, sourceURL);
       }
 
       @Override
@@ -70,7 +74,7 @@ public abstract class JSBundleLoader {
     return new JSBundleLoader() {
       @Override
       public void loadScript(ReactBridge bridge) {
-        bridge.loadScriptFromNetworkCached(sourceURL, null);
+        bridge.loadScriptFromFile(null, sourceURL);
       }
 
       @Override

ReactAndroid/src/main/java/com/facebook/react/bridge/ReactBridge.java

@@ -65,7 +65,7 @@ public class ReactBridge extends Countable {
    * All native functions are not thread safe and appropriate queues should be used
    */
   public native void loadScriptFromAssets(AssetManager assetManager, String assetName);
-  public native void loadScriptFromNetworkCached(String sourceURL, @Nullable String tempFileName);
+  public native void loadScriptFromFile(@Nullable String fileName, @Nullable String sourceURL);
   public native void callFunction(int moduleId, int methodId, NativeArray arguments);
   public native void invokeCallback(int callbackID, NativeArray arguments);
   public native void setGlobalVariable(String propertyName, String jsonEncodedArgument);

ReactAndroid/src/main/java/com/facebook/react/devsupport/DevSupportManager.java

@@ -367,10 +367,18 @@ public class DevSupportManager implements NativeModuleCallExceptionHandler {
   }
 
   public String getSourceMapUrl() {
+    if (mJSAppBundleName == null) {
+      return "";
+    }
+
     return mDevServerHelper.getSourceMapUrl(Assertions.assertNotNull(mJSAppBundleName));
   }
 
   public String getSourceUrl() {
+    if (mJSAppBundleName == null) {
+      return "";
+    }
+
     return mDevServerHelper.getSourceUrl(Assertions.assertNotNull(mJSAppBundleName));
   }