AS3初探

开发工具：FLEX BUILDER3 PRO

语言：AS 3.0

操作系统：Windows XP SP2

1. 在flex3 里新建一个AS工程取名为login2

2. 导入所需要的包（如果无法使用fl包，请参照我的前一篇文章：flex3 里如何导入FLASH CS3的包）

import fl.controls.Button;

import fl.controls.Label;

import fl.controls.TextInput;

import flash.display.Sprite;

import flash.events.MouseEvent;

3. 定义变量（将来在舞台上出现的对象）

//用户名标签和输入框

private var username_label:Label;

private var username_txt:TextInput;

//密码标签和输入框

private var pwd_label:Label;

private var pwd_txt:TextInput;

//登录按钮

private var login_btn:Button;

//提示消息

private var showmsg_label:Label;

4. 定义函数让以上的对象并添加到在舞台上

//定义用户名标签函数

private function setusernamelabel():void

{

username_label = new Label();

username_label.text = "UserName" ;

username_label.move(10,10);

this.addChild(username_label);

}

private function setusernametxt():void

{

username_txt = new TextInput();

username_txt.move(90,10);

this.addChild(username_txt);

}

//定义密码标签函数

private function setpwdlabel():void

{

pwd_label = new Label();

pwd_label.text = "PassWord" ;

pwd_label.move(10,40);

this.addChild(pwd_label);

}

private function setpwdtxt():void

{

pwd_txt = new TextInput();

pwd_txt.displayAsPassword = true ;

pwd_txt.move(90,40);

this.addChild(pwd_txt);

}

//初始化状态信息标签

private function setshowmsg():void

{

showmsg_label = new Label();

showmsg_label.move(90,100);

showmsg_label.text = "";

this.addChild(showmsg_label);

}

//定义login按钮函数

private function setButton():void

{

login_btn = new Button();

login_btn.label = "Login" ;

login_btn.move(90,70);

login_btn.addEventListener(MouseEvent.CLICK,login_click);

this.addChild(login_btn);

}

5. 定义事件函数，这里定义的是鼠标事件

private function login_click(e:MouseEvent):void

{

if (username_txt.text != "admin" || pwd_txt.text != "admin")

{

showmsg_label.text = "UserName or Password is Error!";

disableText();

}

else

{

showmsg_label.text = "Login Success!";

}

}

6. 在构造函数里初始化这些函数，否则舞台上是不会显示任何东西的，注意在这个函数过程中任何对象的引用都要先初始化，否则会提示无法引用空对象！

private function setshowmsg():void

{

showmsg_label = new Label();

showmsg_label.move(90,100);

showmsg_label.text = "";

this.addChild(showmsg_label);

}

7. 测试。

8. 完整代码：

package {

import fl.controls.Button;

import fl.controls.Label;

import fl.controls.TextInput;

import flash.display.Sprite;

import flash.events.MouseEvent;

public class login2 extends Sprite

{

//用户名标签和输入框

private var username_label:Label;

private var username_txt:TextInput;

//密码标签和输入框

private var pwd_label:Label;

private var pwd_txt:TextInput;

//登录按钮

private var login_btn:Button;

//提示消息

private var showmsg_label:Label;

public function login2()

{

setusernamelabel();

setusernametxt();

setpwdlabel();

setpwdtxt();

setButton();

setshowmsg();

}

//定义用户名标签函数

private function setusernamelabel():void

{

username_label = new Label();

username_label.text = "UserName" ;

username_label.move(10,10);

this.addChild(username_label);

}

private function setusernametxt():void

{

username_txt = new TextInput();

username_txt.move(90,10);

this.addChild(username_txt);

}

//定义密码标签函数

private function setpwdlabel():void

{

pwd_label = new Label();

pwd_label.text = "PassWord" ;

pwd_label.move(10,40);

this.addChild(pwd_label);

}

private function setpwdtxt():void

{

pwd_txt = new TextInput();

pwd_txt.displayAsPassword = true ;

pwd_txt.move(90,40);

this.addChild(pwd_txt);

}

//初始化状态信息标签

private function setshowmsg():void

{

showmsg_label = new Label();

showmsg_label.move(90,100);

showmsg_label.text = "";

this.addChild(showmsg_label);

}

//定义login按钮函数

private function setButton():void

{

login_btn = new Button();

login_btn.label = "Login" ;

login_btn.move(90,70);

login_btn.addEventListener(MouseEvent.CLICK,login_click);

this.addChild(login_btn);

}

private function login_click(e:MouseEvent):void

{

if (username_txt.text != "admin" || pwd_txt.text != "admin")

{

showmsg_label.text = "UserName or Password is Error!";

disableText();

}

else

{

showmsg_label.text = "Login Success!";

}

}

private function disableText():void

{

username_txt.enabled = false ;

pwd_txt.enabled = false ;

}

}

}