Command Pattern for MVC web based

[Pawanpreet Singh]

I am working to make a design for developing a command pattern in MVC web based application. I am using an ActionFactory whose static method is called from ServletController. Am i doing right. Should i use static method or do i create a one time object of ActionFactory in ServletController and call it non-static public method for getting the Action per request basis.

Also could you please let me know that is command pattern(behavioural) same as Factory Pattern(creational)?

[Stan James]

I like this kind of thing a lot. I use something like:

String commandKey = some field from the request
Command command = CommandFactory.getCommandFor( commandKey );
command.execute( request, response );

This uses a static method, which is pretty common. Folks interested in maximum flexibility and testability avoid hard-coded class dependencies like CommandFactory and static methods, but that's general OO theory not specific to this problem. If you want to dig into that topic, scroll down to the OO, UML, etc. forum.

Here are some options ... I left out casting and exceptions and such for brevity ...

// I already have a single instance of each command
public Command getCommand( key )
{
   return map.get( key ); 
}
 
// I make a new instance every time
public Command getCommand( key )
{
   String className = map.get( key );
   return Class.forName( className ).newInstance();
}
 
// Load the map at startup in some "application assembler" object
public void assemble()
{
   for each key-className mapping in configuration
      CommandFactory.addMapping( key, classname )
}

[Pawanpreet Singh]

Thanks a lot, James