GWT自定义事件处理程序 [英] GWT Custom Event Handler

问题描述

有人可以给我一个创建事件和处理程序的自定义集的示例。
假设你有一个Person对象，你想要你的小部件知道它是否被更新。

你创建一个HandlerManager，现在你必须创建一个事件一个处理者
您将如何定义这些类，以便您可以订阅和触发事件？

大多数事件都是基于DOM的，而我想要创建一些自定义事件和/或> h2_lin>解决方案

这是一个非常全面的创建自定义事件的例子，从 GwtEventSystem Wiki 逐字删除（当事件系统仍然在GWT的孵化器）。

这是一个事件，当用户开心时触发。

定义一个新的事件类。您可以在事件类中添加任意的元数据。为简单起见，我们不会包含任何内容。

  public class HappyEvent extends GwtEvent {
 ... 
} 
  

为事件类定义一个新的处理程序和标记界面。

 接口HappyHandler扩展EventHandler {
 public void onHappiness（HappyEvent event）; 
} 
 
接口HasHappyEvents {
 public HandlerRegistration addHappyHandler（HappyHandler handler）; 
} 
  

添加唯一的事件类型

  class HappyEvent extends AbstractEvent {
 public static AbstractEvent.Key KEY = new AbstractEvent.Key（）{...} 
 
 public GwtEvent .Key getKey（）{
 return KEY; 
} 
 ... 
} 
  

fire方法

  class HappyEvent extends GwtEvent {
 static Key&HappyEvent，HappyHandler& KEY = new Key&HappyEvent，HappyHandler>（）{
 protected void fire（HappyHandler handler，HappyEvent event）{
 handler.onHappiness（event）; 
}; 
 ... 
} 
  

Can someone give me an example of creating a custom set of an Event and a Handler. Say you have a Person object that you want your widgets to know if it got updated.

You create a HandlerManager and now you have to create an Event and a Handler. How would you define those classes so that you can subscribe and fire events?

Most of the Events are DOM based, while I want to create some custom events and handlers that I can fire outside of any browser-based event.

解决方案

Here's a pretty comprehensive example of creating a custom event, taken verbatim from the GwtEventSystem Wiki (when the event system was still in GWT's incubator).

This is an event that is triggered when the user becomes happy.

Define a new event class. You can add arbitrary metadata in the event class. For simplicity, we will not include any here though.

public class HappyEvent extends GwtEvent {
  ...
}

Define a new handler and marker interface for the event class.

interface HappyHandler extends EventHandler {
  public void onHappiness(HappyEvent event);
}

interface HasHappyEvents {
  public HandlerRegistration addHappyHandler(HappyHandler handler);
}

Add a unique event type

class HappyEvent extends AbstractEvent{
  public static AbstractEvent.Key KEY = new AbstractEvent.Key(){...}

  public GwtEvent.Key getKey(){
    return KEY; 
  }
  ...
}

Wire up the handler's fire method

class HappyEvent extends GwtEvent {
  static Key<HappyEvent,HappyHandler> KEY = new Key<HappyEvent,HappyHandler>(){
    protected void fire(HappyHandler handler, HappyEvent event) {
       handler.onHappiness(event);
    };
   ...
}

这篇关于GWT自定义事件处理程序的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！