FLEX : Validator 验证
Data Access and Interconnectivity / Validating Data：
http://livedocs.adobe.com/flex/3/html/help.html?content=validators_2.html
文件上传验证validator例子：
http://www.adobe.com/devnet/flex/articles/custom_validator.html
是否相等validator例子：
http://blowingthroughlines.com/2009/02/18/uncategorized/flex-custom-validator-email-confirmation/
