Question

My question is simple. In some websites it is seen one can enter the site providing his/her email-id or userid and password(i.e already registered with the site). Now in MVC structure we use servlet as DECISION CONTROLLER. So after taking the input in servlet, we can compare them with userid or email-id column of user table. So to take input we can write in servlet:

String input=request.getParameter("inputfield");

After taking the input what should be the way to check ,if the given input is email-id or userid? Should we compare the String input with each value of both the userid and emailid column of user table? If that is the only way the program quality will be very low and security can be exploited.

Answer 1

email ids have specific syntax…

So use Regular expression to detect email pattern.

If the pattern matches (meaning email id is valid) fire

SELECT email FROM user

else

SELECT username FROM user

Simple 🙂