How to use open closed principle for web page operations invocation in java?

Question

I have a web page where users can fill in and submit forms:

 <form id=email...
 send email ....
 <input type="hidden"id="method" value="sendemail"...
 />
  .............

 <form id=writeindatabase
 some data
      ............
 <input type="hidden"id="method"  value="writeindatabase"...

On the server side:

if (method.compareTo("sendemail")==0) {
 doSendEmail(....
}
else if (method.compareTo("writeindatabase")==0) {
  doWriteInDatabase(....

 ..............................

I don't like this architecture because it violates the open close principle. Is it possible to refactor this to fix that? Thanks.

why don't you just have both forms redirect to different URLs? — kutschkem, Feb 21 '13 at 14:25
What you could do is change the `action` attribute in your form and let the Container dispatch to the correct Servlet or Controller (eg. if you're using Spring). — Sotirios Delimanolis, Feb 21 '13 at 14:26
I use MVC. It is only 1 web page. For 1 web page create many servlets and controllers - will be more repeatable code. Answer should be the same page with added result of operation. Now I have 1 web page, 1 controller 1 view model. If I will create many servlets and controllers for 1 web page it will be difficult to make it work toghether. — user710818, Feb 21 '13 at 14:33

score 2 · Accepted Answer · answered Feb 21 '13 at 14:43

You can use reflection in a structured, secure manner, or, similarly the Command Pattern.

Reflection: make a Map<String, Method> that maps each acceptable method name to a Reflection Method object which you can invoke after looking it up.
Command Pattern: use a Map<String, Callable<?>> in a manner similar to above. Instantiate the Callables as anonymous inner classes that implement call by invoking the appropriate service method.

How to use open closed principle for web page operations invocation in java?

1 Answers1