ASP.NET服务器端或客户端的验证控件？

引自MSDN Document for ASP.NET Validation Controls

Validation controls perform input checking in server code. When the
user submits a page to the server,the validation controls are invoked
to check the user input,control by control. Validation occurs after
page initialization (that is,after view state and postback data have
been processed) but before any change or click event handlers are
called.

ASP.NET performs validation on the server even if the validation
controls have already performed it on the client,so that you can test
for validity within your server-based event handlers.

You can invoke validation in your own code by calling a validation control’s Validate method