Spring MVC framework is very flexible framework for developing the web based enterprise applications. We have many options for creating forms and validating.
So, server side validation of form is a must. In Spring framework you can use the Hibernate validator framework for validation purpose.
You just have to use the annotation in the Form class and then Spring MVC framework will perform validation for you.
Form example for validating you can use following annotation:
@Size(min = 1, max = 20)
private String userName;
Above annotation validates userName value entered by user. It accepts text with a length between 1 and 20.
If validation error then it will display the error message in the jsp page. In jsp page you can add following code for displaying the error message:
<td>User Name:<font color="red"><form:errors path="userName" /></font></td>
You can view complete video tutorial at Spring 3 MVC Validation Example.