# Flutter Module in Android
###### tags: `Flutter` `Work`
[TOC]

## Step 1: Set Flutter Module and Android Project
New a **Flutter Module** and an **Android Project** in the same folder at **same level**.
1. **New a Flutter Module** `flutter create -t module --org com.example flutter_module`
2. **New an Android Project**
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## Step 2: Build Flutter Module aar
Run `flutter build aar` to get the aar that Android Project is going to use.

## Step 3: **Android Project:** Edit settings.gradle
1. Make sure it is `RepositoriesMode.PREFER_PROJECT`
2. Add storageUrl for flutter download and direction to your flutter module.

dependencyResolutionManagement {
repositoriesMode.set(RepositoriesMode.PREFER_PROJECT)
    repositories {
        google()
        mavenCentral()
        String storageUrl = "https://storage.googleapis.com"
        maven {
            url '../../name_of_module/build/host/outputs/repo'
        }
        maven {
            url "$storageUrl/download.flutter.io"
        }// Warning: this repository is going to shut down soon
    }
}

## Step 4: **Android Project:** Edit build.gradle(:app) & build.gradle(project level)
In **build.gradle(:app)**, you must :
1. Copy the settings.gradle repository section and add it here. (Same in build.gradle Project Level)

repositories {
    google()
    mavenCentral()
    String storageUrl = "https://storage.googleapis.com"
    maven {
        url '../../name_of_module/build/host/outputs/repo'
    }
    maven {
        url "$storageUrl/download.flutter.io"
    }
}

2. Add profile setting in buildTypes:

profile {
    initWith debug
}

3. Add the following dependencies:

debugImplementation 'com.example.name_of_module:flutter_debug:1.0'
profileImplementation 'com.example.name_of_module:flutter_profile:1.0'
releaseImplementation'com.example.name_of_module:flutter_release:1.0'

## Step 5: **Android Project:** Link to Flutter Module Activity
### 5.1 Set up Flutter Engine
Set up Flutter Engine which connects the aar and the Android Project.
It is recommended to set it up in **Application class**, which must also be set up in **AndroidManifest.xml**.

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.zc.testandroid">

    <application
        android:name=".AppSettings">
    <activity
        android:name="io.flutter.embedding.android.FlutterActivity"
        android:theme="@style/MyTheme"
        android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
        android:hardwareAccelerated="true"
        android:windowSoftInputMode="adjustResize" />
    </application>
</manifest> 

Take below as example:

public class AppSettings extends Application {
    static String FLUTTER_ENGINE_ID = "flutter_engine";
    FlutterEngine flutterEngine;

    @Override
    public void onCreate() {
        super.onCreate();
        flutterEngine = new FlutterEngine(this); flutterEngine.getDartExecutor().executeDartEntrypoint(DartExecutor.DartEntrypoint.createDefault());
        FlutterEngineCache.getInstance().put(FLUTTER_ENGINE_ID, flutterEngine);
    }
}

### 5.2 Set up Manifest: Add FlutterActivity

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.zc.testandroid">

    <application
        android:name=".AppSettings">
    <activity
        android:name="io.flutter.embedding.android.FlutterActivity"
        android:theme="@style/MyTheme"
        android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
        android:hardwareAccelerated="true"
        android:windowSoftInputMode="adjustResize" />
    </application>
</manifest> 

### 5.3 Jump to Flutter Module main.dart
Must make sure that your `FLUTTER_ENGINE_ID` is the same one as you set in `FlutterEngine` in Application Class.

startActivity(FlutterActivity
    .withCachedEngine(FLUTTER_ENGINE_ID)
    .build(MainActivity.this));

# Reference
* https://levelup.gitconnected.com/how-to-add-flutter-to-android-app-4d80d9820686
* https://blog.codemagic.io/integrating-flutter-module-to-your-native-app/