Servlet request processing

Question

Greetings,

I have a servlet which pulls an "action" parameter from a querystring. Based on this string I perform the required action.

What is the best way to check the value of the "action" parameter. Currently my code is a long if, else if, else if, else if...when I'd rather have some kind of mapping from string to method where I didn't have so many branch conditions.

Regards,

Ken

score 3 · Accepted Answer · edited May 23 '17 at 12:04

3

Populate a Map<String, Action> where String represents the condition for which you would like to grab the action and Action is the interface which you've definied for your actions.

E.g.

Action action = actions.get(request.getMethod() + request.getPathInfo());
if (action != null) {
    action.execute(request, response);
}

You can find a detailed example in this answer.

edited May 23 '17 at 12:04

Community

1
1

answered Nov 29 '10 at 16:43

BalusC

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score 0 · Answer 2 · answered Nov 29 '10 at 16:43

0

One possible way is to keep them in a file (XML file or Properties file). Load them into the memory. It can be stored in some Map. Based the key, the operation(value) can be decided.

answered Nov 29 '10 at 16:43

aNish

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score 0 · Answer 3 · answered Nov 29 '10 at 16:45

Maybe using a helper class with an enum type might help:

public class ActionHelper {
    public enum ServletAction {
         ActionEdit,
         ActionOpen,
         ActionDelete,
         ActionUndefined
    }

    public static ServletAction getAction(String action)
    {
         action = action != null ? action : "";
         if (action.equalsIgnoreCase("edit")) 
             return ServletAction.ActionEdit;
         else if (action.equalsIgnoreCase("open")) 
             return ServletAction.ActionOpen;
         else if (action.equalsIgnoreCase("delete")) 
             return ServletAction.ActionDelete;
         return ServletAction.ActionUndefined;
    }
}

Then, your servlet will have something short and simple like:

ServletAction sa = ActionHelper.getAction(request.getParameter("action"));
switch (sa) {
    case ServletAction.ActionEdit:
        //
        break;
    // ... more cases
}

Servlet request processing

3 Answers3