Android打开Flutter页面

1. 调起Flutter页面

• 在Android项目的清单文件AndroidManifest中添加FlutterActivity

• 跳转到FlutterActivity

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        findViewById(R.id.btn).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                startActivity(
                        FlutterActivity.createDefaultIntent(MainActivity.this)
                );
            }
        });
    }
}

注意：经过运行发现，点击按钮跳转到Flutter页面的时候启动很慢。

2. 优化启动速度

class MainActivity : AppCompatActivity() {

    private lateinit var flutterEngine: FlutterEngine
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        flutterEngine = initFlutterEngine()
        findViewById(R.id.btn).setOnClickListener {
            startActivity(
                FlutterActivity.withCachedEngine("default_engine_id").build(this)
            )
        }
    }

    private fun initFlutterEngine(): FlutterEngine {
        //创建Flutter引擎
        val flutterEngine = FlutterEngine(this)
        //指定要跳转的flutter页面
        flutterEngine.navigationChannel.setInitialRoute("main")
        flutterEngine.dartExecutor.executeDartEntrypoint(DartExecutor.DartEntrypoint.createDefault())
        //这里做一个缓存，可以在适当的时候执行它，例如app里，在跳转前执行预加载
        val flutterEngineCache = FlutterEngineCache.getInstance()
        flutterEngineCache.put("default_engine_id", flutterEngine)
        return flutterEngine
    }

    override fun onDestroy() {
        super.onDestroy()
        flutterEngine.destroy()
    }
}

Flutter代码：

void main() => runApp(const MyApp());

Widget getRouter(String name) {
  switch (name) {
    case "main":
      return const MyApp();
    default:
      return MaterialApp(
        title: "Flutter Demo",
        theme: ThemeData(primarySwatch: Colors.blue),
        home: Container(
          alignment: Alignment.center,
          child: Text("not font page ${name}"),
        ),
      );
  }
}

经过运行发现启动变快。