android混合flutter

1.创建原生项目

会出现如下问题：

A problem occurred evaluating project ':flutter'.
> Failed to apply plugin 'com.android.internal.library'.
   > Android Gradle plugin requires Java 11 to run. You are currently using Java 1.8.
     You can try some of the following options:
       - changing the IDE settings.
       - changing the JAVA_HOME environment variable.
       - changing `org.gradle.java.home` in `gradle.properties`.

解决办法：
修改对应jdk版本为11即可。

2.创建flutter module

 // com.example 是包名 my_flutter是module名
 flutter create -t module --org com.example my_flutter

3.配置原生项目

settings.gradle文件

setBinding(new Binding([gradle: this]))                                
evaluate(new File(                                                    
        settingsDir.parentFile,   // 项目内的目录的File路径
        'my_flutter/.android/include_flutter.groovy'                        
))
include ':my_flutter'

（1）编译会报如下错误：

Caused by: org.gradle.api.internal.plugins.PluginApplicationException: Failed to apply plugin class 'FlutterPlugin'.

解决办法：
settings.gradle文件中，FAIL_ON_PROJECT_REPOS 改为 PREFER_PROJECT

dependencyResolutionManagement {
    repositoriesMode.set(RepositoriesMode.FAIL_ON_PROJECT_REPOS)
    repositories {
        google()
        mavenCentral()
    }
}

（2）编译会报如下错误：

Execution failed for task ':app:checkDebugAarMetadata'.
> Could not resolve all files for configuration ':app:debugRuntimeClasspath'.
   > Could not find org.jetbrains.kotlin:kotlin-stdlib-jdk8:1.6.21.
     Searched in the following locations:
       - https://storage.googleapis.com/download.flutter.io/org/jetbrains/kotlin/kotlin-stdlib-jdk8/1.6.21/kotlin-stdlib-jdk8-1.6.21.pom
     If the artifact you are trying to retrieve can be found in the repository but without metadata in 'Maven POM' format, you need to adjust the 'metadataSources { ... }' of the repository declaration.

解决办法：
原生项目build.gradle文件中新增如下

allprojects {
    repositories {
        google()
        mavenCentral()
    }
}

4.原生跳转flutter module

（1）AndroidManifest.xml

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

（2）app 目录下 build.gradle

implementation project(':flutter')

（3）MainActivity.class

findViewById<TextView>(R.id.tv_jump).setOnClickListener {
            startActivity(FlutterActivity.createDefaultIntent(this))
        }

5.其他问题

（1）如果更改了flutter sdk 目录（项目环境改变，如换电脑、git clone 等等），会出现如下问题：

...\module_plugin_loader.gradle' as it does not exist.

解决办法：
在flutter module 中执行如下命令

flutter packages upgrade
flutter pub get

（2）这样跳转会很慢，大概3秒的延迟，所以先创建FlutterEngine缓存起来：

public class App extends Application {
    private FlutterEngine flutterEngine;

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

    @Override
    public void onTerminate() {
        flutterEngine.destroy();
        super.onTerminate();
    }
}

跳转方式改为（直接调用缓存FlutterEngine）：

startActivity(
                FlutterActivity
                    .withCachedEngine("my_engine_id")
                    .build(this)
            )