JSP和Servlet中的表单验证

Question

I am new to JSP and servlet, could you help me for form validation like to check weather text field is empty or not, in an easy way. Thank you!

Answer 1

You can do the validation both at client side and server side. You can use either JavaScript or JQuery to validate at client side.

Here are the references for them:

• Using JQuery
• Using JavaScript

Here is the example which explains how to handle form post data at the server side using Servlet:

<form action="formpost" method="post">
<input type="text" name="name" />
<input type="text" name="age" />
<input type="submit" />
</form>

Write the servlet reads the post parameters and validates them:

public class FormPost extends HttpServlet
{
 protected void service(HttpServletRequest request, 
   HttpServletResponse responst) throws ServletException, IOException
 {

   if(request.getParameter("name") != null){
      String nameParameter = request.getParameter("name");
   } else {
       //write you validation code here
   }

   int ageParameter = Integer.parseInt(request.getParameter("age"));



 }

}

Answer 2

If purely using JSP and Servlet, i recommend springing off from JavaScript abstraction libraries like JQuery for this task.

Such is the bassistance plugin http://bassistance.de/jquery-plugins/jquery-plugin-validation/

Answer 3

You can do client side input validation. I suggest to use JQUery plugin for validation .