blocks|key|1334592|text|听起来你想要PropertyChange*支持。看看gwtx吧。谷歌'gwt+PropertyChange‘，你会得到多个博客，解释如何使用它。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1334593|entityMap|0|LINK|mutability|MUTABLE|url|http://code.google.com/p/gwtx/^0|Q|4|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Sounds like you want PropertyChange* support. Have a look at <a href="http://code.google.com/p/gwtx/" rel="nofollow noreferrer" title="gwtx">gwtx</a>. Google 'gwt PropertyChange' and you will get multiple blogs that explain how to use it.

blocks|key|943626|text|您可能想看看GWT1.6中的ValueChangeHandler和ValueChangeEvent。这些可能会对你想做的事情起作用。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|943627|entityMap|0|LINK|mutability|MUTABLE|url|http://google-web-toolkit.googlecode.com/svn/javadoc/1.6/com/google/gwt/event/logical/shared/ValueChangeHandler.html|1|http://google-web-toolkit.googlecode.com/svn/javadoc/1.6/com/google/gwt/event/logical/shared/ValueChangeEvent.html#ValueChangeEvent(I)^0|E|I|0|X|G|1|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]|$A|R|B|S|1|T]]|C|$]]|$1|D|3|-4|5|6|7|U|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]|L|$5|G|H|I|C|$J|M]]]]

You might want to have a look at the <a href="http://google-web-toolkit.googlecode.com/svn/javadoc/1.6/com/google/gwt/event/logical/shared/ValueChangeHandler.html" rel="nofollow noreferrer">ValueChangeHandler</a> and <a href="http://google-web-toolkit.googlecode.com/svn/javadoc/1.6/com/google/gwt/event/logical/shared/ValueChangeEvent.html#ValueChangeEvent(I)" rel="nofollow noreferrer">ValueChangeEvent</a> in GWT 1.6. Those might work for what you're trying to do.

blocks|key|943652|text|这里有一个非常全面的创建自定义事件的示例，它是从GwtEventSystem+Wiki中逐字提取的(当时事件系统还在GWT的孵化器中)。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|943653|这是当用户变得快乐时触发的事件。|943654|定义一个新的事件类。您可以在event类中添加任意元数据。不过，为了简单起见，我们不会在这里包含任何内容。|943655|public+class+HappyEvent+extends+GwtEvent+{
++...
}|code-block|syntax|javascript|943656|为事件类定义新的处理程序和标记接口。|943657|interface+HappyHandler+extends+EventHandler+{
++public+void+onHappiness(HappyEvent+event);
}

interface+HasHappyEvents+{
++public+HandlerRegistration+addHappyHandler(HappyHandler+handler);
}|943658|添加唯一的事件类型|943659|class+HappyEvent+extends+AbstractEvent{
++public+static+AbstractEvent.Key+KEY+=+new+AbstractEvent.Key(){...}

++public+GwtEvent.Key+getKey(){
++++return+KEY;+
++}
++...
}|943660|连接处理程序的fire方法|943661|class+HappyEvent+extends+GwtEvent+{
++static+Key<HappyEvent,HappyHandler>+KEY+=+new+Key<HappyEvent,HappyHandler>(){
++++protected+void+fire(HappyHandler+handler,+HappyEvent+event)+{
+++++++handler.onHappiness(event);
++++};
+++...
}|943662|entityMap|0|LINK|mutability|MUTABLE|url|http://code.google.com/p/google-web-toolkit-incubator/wiki/GwtEventSystem^0|O|J|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@$A|17|B|18|1|19]]|C|$]]|$1|D|3|E|5|6|7|1A|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|1B|8|@]|9|@]|C|$]]|$1|H|3|I|5|J|7|1C|8|@]|9|@]|C|$K|L]]|$1|M|3|N|5|6|7|1D|8|@]|9|@]|C|$]]|$1|O|3|P|5|J|7|1E|8|@]|9|@]|C|$K|L]]|$1|Q|3|R|5|6|7|1F|8|@]|9|@]|C|$]]|$1|S|3|T|5|J|7|1G|8|@]|9|@]|C|$K|L]]|$1|U|3|V|5|6|7|1H|8|@]|9|@]|C|$]]|$1|W|3|X|5|J|7|1I|8|@]|9|@]|C|$K|L]]|$1|Y|3|-4|5|6|7|1J|8|@]|9|@]|C|$]]]|Z|$10|$5|11|12|13|C|$14|15]]]]

Here's a pretty comprehensive example of creating a custom event, taken verbatim from the <a href="http://code.google.com/p/google-web-toolkit-incubator/wiki/GwtEventSystem" rel="noreferrer">GwtEventSystem Wiki</a> (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.

<pre><code>public class HappyEvent extends GwtEvent {
 ...
}
</code></pre>

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

<pre><code>interface HappyHandler extends EventHandler {
 public void onHappiness(HappyEvent event);
}

interface HasHappyEvents {
 public HandlerRegistration addHappyHandler(HappyHandler handler);
}
</code></pre>

Add a unique event type

<pre><code>class HappyEvent extends AbstractEvent{
 public static AbstractEvent.Key KEY = new AbstractEvent.Key(){...}

 public GwtEvent.Key getKey(){
 return KEY; 
 }
 ...
}
</code></pre>

Wire up the handler's fire method

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

blocks|key|943733|text|感谢所有的回复。Zakness最接近于给我我需要的答案，然而，我提出了一个稍微简单的模型。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|943734|我的主要目标是避免在我的主数据结构中使用静态变量。我还遇到了这样的问题:在试图访问主数据结构时，是否从数据库中成功地检索到了它，以及当它不成功时(即，当它为空时)该怎么办。|943735|在看了来自谷歌IO的Google+Web+Toolkit+Architecture:+Best+Practices+For+Architecting+Your+GWT+App视频后，事件总线的想法看起来很完美。|offset|length|943736|我会在这里发布我的解决方案，以防它对其他人有帮助。|943737|943738|首先，创建Handler类。注意对Event类的引用：|943739|public+interface+CategoryChangeHandler+extends+EventHandler+{
++++void+onCategoryChange(CategoryChangeEvent+event);
}|code-block|syntax|javascript|943740|现在转到Event类。这给我带来了最大的麻烦：|943741|public+class+CategoryChangeEvent+extends+GwtEvent<CategoryChangeHandler>+{

++++private+final+List<Category>+category;

++++public+CategoryChangeEvent(List<Category>+category)+{
++++++++super();
++++++++this.category+=+category;
++++}

++++public+static+final+Type<CategoryChangeHandler>+TYPE+=+new+Type<CategoryChangeHandler>();

++++@Override
++++protected+void+dispatch(CategoryChangeHandler+handler)+{
++++++++handler.onCategoryChange(this);
++++}

++++@Override
++++public+com.google.gwt.event.shared.GwtEvent.Type<CategoryChangeHandler>+getAssociatedType()+{
++++++++return+TYPE;
++++}

++++public+List<Category>+getCategories(){
++++++++return+category;
++++}

}|943742|现在，当这个主数据结构重新加载时，我可以像这样使用这些处理程序和事件类：|943743|这段代码获得了数据结构，并希望通知正在监听的每个人它已更新：|943744|CategoryChangeEvent+event+=+new+CategoryChangeEvent(result);
eventBus.fireEvent(event);|943745|此代码是事件的实现|943746|public+class+PopulateCategoryHandler+implements+CategoryChangeHandler+{

++++@Override
++++public+void+onCategoryChange(CategoryChangeEvent+event)+{
++++++++tearDownCategories();

++++++++List<Category>+categories+=+event.getCategories();
++++++++populateCategories(categories);+
++++}

}|943747|entityMap|0|LINK|mutability|MUTABLE|url|http://code.google.com/events/io/sessions/GoogleWebToolkitBestPractices.html^0|0|0|A|25|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1D|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1E|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|1F|8|@]|9|@$F|1G|G|1H|1|1I]]|A|$]]|$1|H|3|I|5|6|7|1J|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|1K|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|1L|8|@]|9|@]|A|$]]|$1|M|3|N|5|O|7|1M|8|@]|9|@]|A|$P|Q]]|$1|R|3|S|5|6|7|1N|8|@]|9|@]|A|$]]|$1|T|3|U|5|O|7|1O|8|@]|9|@]|A|$P|Q]]|$1|V|3|W|5|6|7|1P|8|@]|9|@]|A|$]]|$1|X|3|Y|5|6|7|1Q|8|@]|9|@]|A|$]]|$1|Z|3|10|5|O|7|1R|8|@]|9|@]|A|$P|Q]]|$1|11|3|12|5|6|7|1S|8|@]|9|@]|A|$]]|$1|13|3|14|5|O|7|1T|8|@]|9|@]|A|$P|Q]]|$1|15|3|-4|5|6|7|1U|8|@]|9|@]|A|$]]]|16|$17|$5|18|19|1A|A|$1B|1C]]]]

Thanks for all the responses. Zakness came the closest to giving me the answer I needed, however, I came up with a slightly simpler model. 

My main goal was to avoid using a static variable to my main data structure. I also hit the problem of trying to figure out if that main data structure was successfully retrieved from the database at the time of trying to access it and what to do when it's not (i.e. when it's null).

After watching the <a href="http://code.google.com/events/io/sessions/GoogleWebToolkitBestPractices.html" rel="noreferrer">Google Web Toolkit Architecture: Best Practices For Architecting Your GWT App</a> video from Google IO, the Event Bus idea seemed perfect.

I'll post my solution here in case it helps anyone else out.

<hr>

First, create the Handler class. Note the reference to the Event class already:

<pre><code>public interface CategoryChangeHandler extends EventHandler {
 void onCategoryChange(CategoryChangeEvent event);
}
</code></pre>

Now on to the Event class. This gave me the most trouble:

<pre><code>public class CategoryChangeEvent extends GwtEvent&lt;CategoryChangeHandler&gt; {

 private final List&lt;Category&gt; category;

 public CategoryChangeEvent(List&lt;Category&gt; category) {
 super();
 this.category = category;
 }

 public static final Type&lt;CategoryChangeHandler&gt; TYPE = new Type&lt;CategoryChangeHandler&gt;();

 @Override
 protected void dispatch(CategoryChangeHandler handler) {
 handler.onCategoryChange(this);
 }

 @Override
 public com.google.gwt.event.shared.GwtEvent.Type&lt;CategoryChangeHandler&gt; getAssociatedType() {
 return TYPE;
 }

 public List&lt;Category&gt; getCategories(){
 return category;
 }

}
</code></pre>

Now I am able to use these Handler and Event classes like so when this main data structure gets reloaded:

This code got the data structure and want to notify everyone who is listening that it got updated:

<pre><code>CategoryChangeEvent event = new CategoryChangeEvent(result);
eventBus.fireEvent(event);
</code></pre>

This code is an implementation of the Event

<pre><code>public class PopulateCategoryHandler implements CategoryChangeHandler {

 @Override
 public void onCategoryChange(CategoryChangeEvent event) {
 tearDownCategories();

 List&lt;Category&gt; categories = event.getCategories();
 populateCategories(categories); 
 }

}
</code></pre>

blocks|key|34640|text|这是an+example+of+this+over+on+Alex+Reid's+blog,+including+a+link+to+an+operational+code+example。该示例填充了一些模糊的部分，并与Nick的示例一起，帮助阐明在gwt应用程序中构建事件总线的入门知识。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|34641|entityMap|0|LINK|mutability|MUTABLE|url|http://phiz.posterous.com/loose-coupling-in-client-side-web-apps-with-g^0|2|2K|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

Here is <a href="http://phiz.posterous.com/loose-coupling-in-client-side-web-apps-with-g" rel="nofollow noreferrer">an example of this over on Alex Reid's blog, including a link to an operational code example</a>. The example fills in some of the fuzzy bits and, along with Nick's example here, helps clarify getting started with architecting an event bus in your gwt application.

blocks|key|34655|text|使用HandlerManger创建自定义GWT事件应该不是很难，看看示例GwtEventBus+@+NingZhang.info它是非常直观的。使用的关键类包括：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|34656|34657|com.google.gwt.event.shared.HandlerManager|unordered-list-item|34658|com.google.gwt.event.shared.GwtEvent|34659|com.google.gwt.event.shared.EventHandler|34660|34661|entityMap|0|LINK|mutability|MUTABLE|url|http://www.ningzhang.info/GwtEventBus^0|10|S|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]|$1|E|3|F|5|G|7|Z|8|@]|9|@]|C|$]]|$1|H|3|I|5|G|7|10|8|@]|9|@]|C|$]]|$1|J|3|K|5|G|7|11|8|@]|9|@]|C|$]]|$1|L|3|-4|5|6|7|12|8|@]|9|@]|C|$]]|$1|M|3|-4|5|6|7|13|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

Create custom GWT events using the HandlerManger shouldn't be this hard, take a look at the example <a href="http://www.ningzhang.info/GwtEventBus" rel="nofollow noreferrer">GwtEventBus @ NingZhang.info</a> it is real intuitive. The key classes used are:

<ul>
<li>com.google.gwt.event.shared.HandlerManager</li>
<li>com.google.gwt.event.shared.GwtEvent</li>
<li>com.google.gwt.event.shared.EventHandler</li>
</ul>

blocks|key|4160879|text|我认为最完整、最详细的例子是this+article|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|4160880|它还包含一个示例项目，该项目准确地展示了如何正确使用、定义自定义事件和使用GWT的HandlerManager类。|4160881|entityMap|0|LINK|mutability|MUTABLE|url|http://code.google.com/webtoolkit/articles/mvp-architecture.html^0|E|C|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@$A|O|B|P|1|Q]]|C|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@]|C|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|C|$]]]|G|$H|$5|I|J|K|C|$L|M]]]]

I think that the most complete and detailed example is in <a href="http://code.google.com/webtoolkit/articles/mvp-architecture.html" rel="nofollow noreferrer">this article</a>

It contains also an example project that shows exactly how to properly use define custom events and use GWT's HandlerManager class.

blocks|key|35074|text|一个额外的评论:如果你尝试在主应用程序中对从自定义GUI组件(如组合等)激发的事件进行类似的反应，我认为你必须显式地连接主应用程序来处理组件的事件：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|35075|yourComponent.addHandler(this,+YourEvent.TYPE);|code-block|syntax|javascript|35076|其中"this“是实现自定义处理程序接口的类。|35077|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

One additional comment: if you try do to something similar to react in a main application to an event fired from a custom GUI component (like a composite etc.), I think you have to wire the main app explicitly to handle the component's event:

<pre><code>yourComponent.addHandler(this, YourEvent.TYPE);
</code></pre>

where "this" is the class that implements your custom handler interface.

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.

GWT Custom Event Handler

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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有人能给我一个创建自定义事件集和处理程序的示例吗？假设您有一个Person对象，您希望小部件知道它是否已更新。您创建了一个HandlerManager，现在您必须创建一个事件和一个处理程序。您如何定义这些类，以便可以订阅和触发事件？大多数事件都是基于DOM的，而我想创建一些可以在任何基于浏览器的事件之外触发的自定义事件...

问GWT自定义事件处理程序
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