dart如何创建，收听和发出自定义事件？ [英] dart how to create, listen, and emits custom event?

问题描述

我有这样的类：

class BaseModel {
  Map objects;

  // define constructor here

  fetch() {
    // fetch json from server and then load it to objects
    // emits an event here
  }

}

像 backbonejs 我想在调用 fetch 并创建侦听器时发出 change 事件我认为是 change 事件。

Like backbonejs i want to emits a change event when i call fetch and create a listener for change event on my view.

但是从阅读文档开始，我不知道从哪里开始有太多指向事件的信息，例如 Event Events EventSource 依此类推。

But from reading the documentation, i don't know where to start since there are so many that points to event, like Event Events EventSource and so on.

你们能给我一个提示吗？

Can you guys give me a hint?

推荐答案

我假设您要发出不需要 dart：html 库存在的事件。

I am assuming you want to emit events that do not require the presence of dart:html library.

您可以使用Streams API公开事件流，以供其他人侦听和处理。例如：

You can use the Streams API to expose a stream of events for others to listen for and handle. Here is an example:

import 'dart:async';

class BaseModel {
  Map objects;
  StreamController fetchDoneController = new StreamController.broadcast();

  // define constructor here

  fetch() {
    // fetch json from server and then load it to objects
    // emits an event here
    fetchDoneController.add("all done"); // send an arbitrary event
  }

  Stream get fetchDone => fetchDoneController.stream;

}

然后，在您的应用程序中：

Then, over in your app:

main() {
  var model = new BaseModel();
  model.fetchDone.listen((_) => doCoolStuff(model));
}

使用本机Streams API很不错，因为这意味着您不需要浏览器以测试您的应用程序。

Using the native Streams API is nice because it means you don't need the browser in order to test your application.

如果需要发出自定义HTML事件，则可以看到以下答案： https://stackoverflow.com/a/13902121/123471

If you are required to emit a custom HTML event, you can see this answer: https://stackoverflow.com/a/13902121/123471

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