Event:

1.事件派发 Dispatching

Flash.events.EventDispacher类提供了事件dispatch函数,如果需要dispatch事件,则应该考虑继承该类或其子类.如果不能继承该类,则应实现IEventDispatcher接口

2.监听事件 Listening to Events

在监听事件时应首先考虑是否要使用weak referenced.如果事件监听与派发与监听函数有共同的生命周期,则可以使用strong referenced,在其他的大部分情况下,则应使用weak referenced.

Bindable的三种实现方式:

1.使用Event实现.

2.MXML中使用大括号实现.

3.AS中使用ChangeWatcher实现.

Event与Bindable举例:

有一个Person类:

view plaincopy to clipboardprint?

1. package com.insprise
2. {
3. import flash.events.Event;
4. import flash.events.EventDispatcher;
5. import mx.events.PropertyChangeEvent;
6. public class Person extends EventDispatcher
7. {
8. private var _name:String;
9. private var _age:int;
10. private var _desc:String;
11. /**
12. * 构造函数
13. */
14. public function Person()
15. {
16. super();
17. }
18. /**
19. * Get&Set Name SetName时dispatch一个PropertyChangeEvent事件
20. */
21. [Bindable(event="propertyChange")]
22. public function get name():String {
23. trace("Get name: " + _name);
24. return _name;
25. }
26. public function set name(name_:String):void {
27. if(name_ == _name) {
28. return;
29. }
30. var old:String = this._name;
31. this._name = name_;
32. trace("Set Name to: " + name_);
33. dispatchEvent(PropertyChangeEvent.createUpdateEvent(this,"name",old,name_));
34. }
35. /**
36. * Get&Set age; age被Set的时候会dispatch一个ageChanged事件.
37. */
38. [Bindable(event="ageChanged")]
39. public function get age():int {
40. trace("Get age: " + _age);
41. return _age;
42. }
43. public function set age(age_:int):void {
44. if(age_ == _age) {
45. return;
46. }
47. var old:int = this._age;
48. this._age = age_;
49. trace("Set Age to: " + age_);
50. dispatchEvent(new Event("ageChanged"));
51. }
52. /**
53. * Get&Set Desc;desc被set时会自动dispatch一个PropertyChangeEvent.
54. */
55. [Bindable]
56. public function get desc():String {
57. trace("Get desc: " + _desc);
58. return _desc;
59. }
60. public function set desc(desc_:String):void {
61. if(desc_ == _desc) {
62. return;
63. }
64. var old:String = this._desc;
65. this._desc = desc_;
66. trace("Set desc to: " + desc_);
67. }
68. }
69. }

现在我们通过上面提到的三种方式实现Bindable:

1.使用Event Bindable:

view plaincopy to clipboardprint?

1. import mx.events.PropertyChangeEvent;
2. import com.insprise.Person;
3. var person:Person = new Person();
4. /**
5. * 监听PropertyChangeEvent与ageChanged事件
6. */
7. private function init():void {
8. person.addEventListener("propertyChange",propertyChangeHandler);
9. person.addEventListener("ageChanged",ageChangedHandler);
10. }
11. /**
12. * 通过对PropertyChangeEvent.property判断是name还是desc被监听,更新屏幕
13. */
14. private function propertyChangeHandler(e:PropertyChangeEvent):void {
15. if(e.property == "name") {
16. textArea_Name.text = e.newValue.toString();
17. }else if(e.property == "desc") {
18. textArea_Desc.text = e.newValue.toString();
19. }else {
20. return;
21. }
22. trace("view: " + e.property + " Changed");
23. }
24. /**
25. * set age之后更新屏幕
26. */
27. private function ageChangedHandler(e:Event):void {
28. textArea_Age.text = String(person.age);
29. }

2.MXML使用大括号:

view plaincopy to clipboardprint?

1. <mx:textarea x="202" y="107" width="131" height="21" wordwrap="true" editable="false" id="textArea_Name" text="{person.name}">
2. <mx:label x="142" y="158" text="Age:">
3. <mx:textarea x="202" y="157" width="131" height="21" wordwrap="true" editable="false" id="textArea_Age" text="{person.age}">
4. <mx:label x="142" y="215" text="Desc:">
5. <mx:textarea x="202" y="214" width="131" height="71" wordwrap="true" editable="false" id="textArea_Desc" text="{person.desc}">
6. </mx:textarea></mx:label></mx:textarea></mx:label></mx:textarea>

3.使用AS中的ChangeWatcher

view plaincopy to clipboardprint?

1. private function init():void {
2. var nameWatcher:ChangeWatcher;
3. var ageWatcher:ChangeWatcher;
4. var descWatcher:ChangeWatcher;
5. var canWatche:ChangeWatcher;
6. //nameWatcher = BindingUtils.bindProperty(textArea_Name,"text",person,"name");
7. ChangeWatcher.watch(person,"name",nameSetter);
8. ageWatcher = BindingUtils.bindProperty(textArea_Age,"text",person,String("age"));
9. descWatcher = BindingUtils.bindProperty(textArea_Desc,"text",person,"desc",true);
10. }
11. private function nameSetter(e:PropertyChangeEvent):void {
12. if(e==null) {
13. return;
14. }
15. textArea_Name.text = e.newValue.toString();
16. trace("Name Changed by nameSetter on the Event " + e + " to " + e.newValue);
17. }
18. private function ageSetter(e:Event):void {
19. //textArea_Age.text = String(person.age);
20. trace("Age is setted by ageSetter on the Event " + " to " + person.age);
21. }