【Flutter 面试】main入口函数会被调用几次

移动开发作者： 2024-08-24 20:50:01

老孟导读：这是一个读者面试时被问到的问题，这个问题前段时间我也在VIP交流群和大家一起探讨过。这个问题涉及引擎的相关知识，如果不了解相关知识，很难回答正确，因为不管说调用几次都是错误的，下面来看一下

class MainActivity : Activity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        findViewById<Button>(R.id.button).setOnClickListener {
            startActivity(Intent(this,FlutterActivity::class.java))
        }
    }
}

void main() {
  runApp(MyApp());
  print('===main====');
}

val flutterEngine = FlutterEngine(this)
flutterEngine.dartExecutor.executeDartEntrypoint(
        DartExecutor.DartEntrypoint.createDefault()
)
FlutterEngineCache
        .getInstance()
        .put("engine_id",flutterEngine)

findViewById<Button>(R.id.button).setOnClickListener {
    startActivity(
            FlutterActivity
                    .withCachedEngine("engine_id")
                    .build(this)
    )
}

void main() {
  runApp(MyApp());
  print('===main====');
}

void main1() {
  runApp(MyApp());
  print('===main1====');
}

class MainActivity : Activity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val flutterEngine = FlutterEngine(this)
        flutterEngine.dartExecutor.executeDartEntrypoint(
//            DartExecutor.DartEntrypoint.createDefault()
                createEntrypoint()
        )
        FlutterEngineCache
                .getInstance()
                .put("engine_id",flutterEngine)

        findViewById<Button>(R.id.button).setOnClickListener {
            startActivity(
                    FlutterActivity
                            .withCachedEngine("engine_id")
                            .build(this)
            )
        }
    }

    fun createEntrypoint(): DartExecutor.DartEntrypoint {
        val flutterLoader: FlutterLoader = FlutterInjector.instance().flutterLoader()
        return DartExecutor.DartEntrypoint(flutterLoader.findAppBundlePath(),"main1")
    }
}