Dart Zone.errorZone用法及代碼示例

錯誤區負責處理未捕獲的錯誤。

這是提供handleUncaughtError 方法的該區域最近的父區域。

異步錯誤永遠不會跨越具有不同錯誤處理程序的區域之間的區域邊界。

例子：

import 'dart:async';

main() {
  var future;
  runZoned(() {
    // The asynchronous error is caught by the custom zone which prints
    // 'asynchronous error'.
    future = Future.error("asynchronous error");
  }, onError: (e) { print(e); });  // Creates a zone with an error handler.
  // The following `catchError` handler is never invoked, because the
  // custom zone created by the call to `runZoned` provides an
  // error handler.
  future.catchError((e) { throw "is never reached"; });
}

請注意，錯誤也不能進入具有不同錯誤處理程序的子區域：

import 'dart:async';

main() {
  runZoned(() {
    // The following asynchronous error is *not* caught by the `catchError`
    // in the nested zone, since errors are not to cross zone boundaries
    // with different error handlers.
    // Instead the error is handled by the current error handler,
    // printing "Caught by outer zone: asynchronous error".
    var future = Future.error("asynchronous error");
    runZoned(() {
      future.catchError((e) { throw "is never reached"; });
    }, onError: (e) { throw "is never reached"; });
  }, onError: (e) { print("Caught by outer zone: $e"); });
}