简单Flex示例_登录

<?xml version="1.0" encoding="utf-8"?>
<mx:WindowedApplication xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute" 
 width="310" height="300" fontSize="12" creationComplete="initApp()" title="用户登录">
 
 <mx:Script>
  <![CDATA[
   import mx.controls.Alert;
   
   private function initApp():void
   {
    this.textCode.text = createCheckCode();
   }
   
   private function loginHandle():void
   {
    var username:String = this.txtUsername.text;
    var password:String = this.txtPassword.text;    
    var inputcode:String = this.txtCode.text;
    var code:String = this.textCode.text;
   
    if(username=="")
    {
     Alert.show("用户名不能为空！");
    }
    
    if(password=="")
    {
     Alert.show("密码不能为空！");
    }
    
    if(username == "Admin" && password == "Pass" && inputcode.toLocaleLowerCase() == code.toLocaleLowerCase())
    {
     currentState="index";      //通过currentState改变状态，即更换界面
    }
    else
    {
     if(inputcode.toLocaleLowerCase() != code.toLocaleLowerCase())
     {
      //使控件获取焦点的写法
      application.focusManager.setFocus(txtCode);   //该花括号内的该行代码必须放在下一行的前面，否则没有该效果出现
      Alert.show("验证码输入错误！");
     }
     else
     {
      Alert.show("用户名或密码错误！");
     }
    }
   }
   
      
    //create validate code
   private function createCheckCode():String
   {
    //初始化
    var ran:Number;
    var number:Number;
    var  code:String;
    var checkCode:String ="";
    //生成四位随机数
    for(var i:int=0; i<4; i++)
    {
     //Math.random生成数为类似为0.1234
     ran=Math.random();
     number =Math.round(ran*10000);
     //如果是2的倍数生成一个数字
     if(number % 2 == 0)
       //"0"的ASCII码是48 
       code = String.fromCharCode(48+(number % 10));
     //生成一个字母
     else 
       //"A"的ASCII码为65
       code = String.fromCharCode(65+(number % 26)) ;
     checkCode += code;
    }
    return checkCode;
   }
  ]]>
 </mx:Script>

 

<!-- about state -->
 <mx:states>
  <mx:State name="index">
   <!-- remove login panel -->
   <mx:RemoveChild target="{pnlLogin}"/>
   <mx:AddChild position="">
    <mx:Label text="Welcome to your new home !" fontSize="13"/>
   </mx:AddChild>
  </mx:State>
 </mx:states>
 
 <mx:Panel width="300" height="280" layout="absolute" id="pnlLogin" fontSize="13" horizontalAlign="center" verticalAlign="middle">
 <mx:Label x="18" y="13" text="用户名" id="lblUsername"/>
 <mx:Label x="18" y="58" text="密码" id="lblPassword"/>
 <mx:Button x="71" y="150" label="登录" id="btnLogin" click="loginHandle()"/>
 <mx:TextInput x="71" y="11" id="txtUsername"/>
 <mx:TextInput x="71" y="58" id="txtPassword" displayAsPassword="true"/>
 <mx:Button x="179" y="150" label="重置" id="btnReset"/>
 <mx:Label x="18" y="107" text="校验码" id="lblCode"/>
 <mx:TextInput x="71" y="105" id="txtCode" width="52"/> 
 <mx:LinkButton x="171" y="105" label="看不清?" id="lnkBtnCode" click="initApp()"/>
 <mx:Text x="131" y="107" id="textCode"/>
 </mx:Panel>
</mx:WindowedApplication>
该示例中包含生成验证码、设置控件的焦点、改变页面的状态（给用户的感觉就是更换页面）。个人认为更换页面的做法上比较麻烦：更换页面的内容需要手写代码；也使页面的代码量变大。不知道有没有其他的写法，搜集中...