flutter - 在dispose()方法内部使用Provider.of(context)调用方法会导致 "Looking up a deactivated widget'的祖先不安全。”

Question

当我尝试在State内调用方法时，请像下面这样处理方法。

  @override
  void dispose() {
    Provider.of<AppProvider>(context, listen: false).close();
    super.dispose();
  }

我懂了。

The following assertion was thrown while finalizing the widget tree:
Looking up a deactivated widget's ancestor is unsafe.

At this point the state of the widget's element tree is no longer stable.

To safely refer to a widget's ancestor in its dispose() method, save a reference to the ancestor by calling dependOnInheritedWidgetOfExactType() in the widget's didChangeDependencies() method.

When the exception was thrown, this was the stack
#0      Element._debugCheckStateIsActiveForAncestorLookup.<anonymous closure> 
package:flutter/…/widgets/framework.dart:3508
#1      Element._debugCheckStateIsActiveForAncestorLookup 
package:flutter/…/widgets/framework.dart:3522
#2      Element.getElementForInheritedWidgetOfExactType 
package:flutter/…/widgets/framework.dart:3588
#3      Provider.of 
package:provider/src/provider.dart:219
#4      _MySecondPageState.dispose 
package:test_space/main.dart:138
...

这是我的示例AppProvider

class AppProvider {
  close() {}
}

我用AppProvider包装了MaterialApp

return Provider<AppProvider>(
      create: (_) => AppProvider(),
      child: MaterialApp(
        title: 'Flutter Demo',
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        home: HomeScreen(),
        },
      ),
    );

我不确定该如何做To safely refer to a widget's ancestor in its dispose() method, save a reference to the ancestor by calling dependOnInheritedWidgetOfExactType() in the widget's didChangeDependencies() method.我目前正在使用provider: ^4.0.2。

我曾经在dispose()内使用Provider.of(context)来做同样的操作，，之前没有这个异常(exception)。这是因为新的flutter版本吗？
另外，我意识到这里有deactivate()方法，我应该使用deactivate()方法而不是dispose()方法吗？

[更新]

  AppProvider _appProvider;
  @override
  void didChangeDependencies() {
    _appProvider = Provider.of<AppProvider>(context, listen: false);
    super.didChangeDependencies();
  }

  @override
  void dispose() {
    _appProvider.close();
    super.dispose();
  }

I could also use deactivate in a certain case

  @override
  void deactivate() {
    Provider.of<AppProvider>(context, listen: false)
        .close();
    super.deactivate();
  }

Answer 1

似乎您正在尝试关闭AppProvider类中定义的内容。如果AppProvider类正在扩展ChangeNotifier，则更改通知程序类提供dispose方法，您可以重写它，然后仅在AppProvider类内调用close函数。