GetxControllers 是否会自动关闭 obs 流？

Question

我正在使用以下包https://pub.dev/packages/get。我需要在 GetxController 的 onClose 中关闭我的 .obs 吗？我在文档中找不到任何关于此的内容。看着我的记忆，它似乎正在被自动销毁。

Answer 1

根据onClose的超级实现代码，默认当前什么都不做。

https://github.com/jonataslaw/getx/blob/7146b6a53c0648104e4f623385deaff055e0036a/lib/get_instance/src/lifecycle.dart#L56

从 cmets 中，它说：

  /// Called before [onDelete] method. [onClose] might be used to
  /// dispose resources used by the controller. Like closing events,
  /// or streams before the controller is destroyed.
  /// Or dispose objects that can potentially create some memory leaks,
  /// like TextEditingControllers, AnimationControllers.
  /// Might be useful as well to persist some data on disk.
  void onClose() {}

我认为您需要在 YourController::onClose() 覆盖函数中手动关闭流。

Answer 2

看来您在使用 GetWorkers 时可以安全地使用 obs。运行这段代码，你会注意到，当你点击按钮几次时，每页切换只会打印一次。

void main(){
  runApp(GetMaterialApp(home: TestWidget(),));
}

class TestWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: RaisedButton(
        child: Text('next'),
        onPressed: () => Get.to<SomeWidget>(SomeWidget()),
      ),
    );
  }
}

class SomeWidget extends StatelessWidget {
  RxBool isSubscribed = false.obs;

  SomeWidget() {
    ever(isSubscribed, (_) => print('test'));
  }

  @override
  Widget build(BuildContext context) {
    return Center(
      child: RaisedButton(
        child: Text('back'),
        onPressed: () {
          isSubscribed.value = !isSubscribed.value;
          Get.back();
        },
      ),
    );
  }
}

Answer 3

在我目前对 GetX + Flutter 的理解中......

不，您不必在 GetxControllers 的 close() 方法中删除 .obs。当控制器从内存中删除时，控制器中的可观察对象的处理会自动完成。

当包含 GetxControllers 的小部件从小部件堆栈中弹出/从小部件树中删除时，GetX 会处理/删除 GetxController（及其可观察对象）（默认情况下，但可以覆盖）。

您可以在各种 Get 小部件的 dispose() 方法的覆盖中看到这一点。

这是dispose() 的 sn-p，在弹出/删除 GetX 小部件时运行：

  @override
  void dispose() {
    if (widget.dispose != null) widget.dispose(this);
    if (isCreator || widget.assignId) {
      if (widget.autoRemove && GetInstance().isRegistered<T>(tag: widget.tag)) {
        GetInstance().delete<T>(tag: widget.tag);
      }
    }
    subs.cancel();
    _observer.close();
    controller = null;
    isCreator = null;
    super.dispose();
  }

当您使用 Bindings 或 Get.to() 时，您使用的是 GetPageRoute，它们通过路由名称进行清理：

  @override
  void dispose() {
    if (Get.smartManagement != SmartManagement.onlyBuilder) {
      WidgetsBinding.instance.addPostFrameCallback((_) => GetInstance()
          .removeDependencyByRoute("${settings?.name ?? routeName}"));
    }
    super.dispose();
  }

测试应用

下面是一个测试应用程序，您可以复制/粘贴到 Android Studio / VSCode 并运行以观察调试或运行窗口输出的 GETX 生命周期事件。

GetX 将记录控制器在内存中的创建和处置。

该应用程序有一个 HomePage 和 3 个 ChildPages 使用 Get Controllers 以 3 种方式，所有这些都从内存中删除：

1. GetX / GetBuilder
2. Get.put
3. 绑定

import 'package:flutter/material.dart';
import 'package:get/get.dart';

void main() {
  // MyCounterBinding().dependencies(); // usually where Bindings happen
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return GetMaterialApp(
      title: 'GetX Dispose Ex',
      home: HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('GetX Dispose Test'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: [
            RaisedButton(
              child: Text('GetX/Builder Child'),
              onPressed: () => Get.to(ChildPage()),
            ),
            RaisedButton(
              child: Text('Get.put Child'),
              onPressed: () => Get.to(ChildPutPage()),
            ),
            RaisedButton(
              child: Text('Binding Child'),
              onPressed: () => Get.to(ChildBindPage()),
            ),
          ],
        ),
      ),
    );
  }
}

/// GETX / GETBUILDER
/// Creates Controller within the Get widgets
class ChildPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('GetX Dispose Test Counter'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: [
            Text('This is the Child Page'),
            GetX<ChildX>(
              init: ChildX(),
              builder: (cx) => Text('Counter: ${cx.counter}', style: TextStyle(fontSize: 20),),
            ),
            GetBuilder<ChildX>(
              init: ChildX(),
              builder: (cx) => RaisedButton(
                child: Text('Increment'),
                onPressed: cx.inc,
              ),
            ),
          ],
        ),
      ),
    );
  }
}

/// GET.PUT
/// Creates Controller instance upon Build, usable anywhere within the widget build context
class ChildPutPage extends StatelessWidget {
  //final ChildX cx = Get.put(ChildX()); // wrong place to put  
  // see https://github.com/jonataslaw/getx/issues/818#issuecomment-733652172

  @override
  Widget build(BuildContext context) {
    final ChildX cx = Get.put(ChildX());
    return Scaffold(
      appBar: AppBar(
        title: Text('GetX Dispose Test Counter'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: [
            Text('This is the Child Page'),
            Obx(
              () => Text('Counter: ${cx.counter}', style: TextStyle(fontSize: 20),),
            ),
            RaisedButton(
              child: Text('Increment'),
              onPressed: cx.inc,
            )
          ],
        ),
      ),
    );
  }
}

class MyCounterBinding extends Bindings {
  @override
  void dependencies() {
    Get.lazyPut(() => ChildX(), fenix: true);
  }
}

/// GET BINDINGS
/// Normally the MyCounterBinding().dependencies() call is done in main(),
/// making it available throughout the entire app.
/// A lazyPut Controller /w [fenix:true] will be created/removed/recreated as needed or
/// as specified by SmartManagement settings.
/// But to keep the Bindings from polluting the other examples, it's done within this
/// widget's build context (you wouldn't normally do this.)
class ChildBindPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    MyCounterBinding().dependencies(); // just for illustration/example

    return Scaffold(
      appBar: AppBar(
        title: Text('GetX Dispose Test Counter'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.spaceEvenly,
          children: [
            Text('This is the Child Page'),
            Obx(
                  () => Text('Counter: ${ChildX.i.counter}', style: TextStyle(fontSize: 20),),
            ),
            RaisedButton(
              child: Text('Increment'),
              onPressed: ChildX.i.inc,
            )
          ],
        ),
      ),
    );
  }
}


class ChildX extends GetxController {
  static ChildX get i => Get.find();
  RxInt counter = 0.obs;

  void inc() => counter.value++;
}

注意事项

Get.to 与 Navigator.push

在子小部件中使用 Get.put() 时，请确保您使用 Get.to() 导航到该子小部件，而不是 Flutter 的内置 Navigator.push。

GetX 在使用Get.to 时将目标小部件包装在GetPageRoute 中。当导航离开/将小部件从堆栈中弹出时，此 Route 类将处理此路由中的控制器。如果您使用 Navigator.push，则不会涉及 GetX，您将不会获得此自动清理。

Navigator.push

onPressed: () => Navigator.push(context, MaterialPageRoute(
                  builder: (context) => ChildPutPage())),

Get.to

onPressed: () => Get.to(ChildPutPage()),