Invoking different methods via Servlets depending upon a URL

Question

I would like invoking methods based on URL mappings using Servlet/JSP.

A Servlet is mapped to a pattern like /xxx/*. I have created an interface with only one method as follows.

public interface Action
{
   public void execute(HttpServletRequest request, HttpServletResponse response) throws IllegalAccessException, InvocationTargetException, SQLException, ServletException, IOException;
}

A java.util.Map initialized with different implementations of this interface to perform different actions based on a URL in the Servlet we are talking about in its init() method as follows.

@WebServlet(name = "Country", urlPatterns = {"/Country/*"})
public final class Country extends HttpServlet
{
    private Map<String, Action>map;

    @Override
    public void init(ServletConfig config) throws ServletException
    {
        super.init(config);
        map=new HashMap<String, Action>();

        map.put("Create", new CreateAction());
        map.put("Read", new ReadAction());
        map.put("Delete", new DeleteAction());
        map.put("Edit", new EditAction());
    }
}

The execute() method is invoked precisely from either the doGet() or doPost() method just like as follows.

map.get(request.getPathInfo().substring(1)).execute(request, response);

For instance, a URL like, http://localhost:8080/Assignment/Country/Create would invoke the execute() method in the CreateAction class.

Similarly, a URL like, http://localhost:8080/Assignment/Country/Delete would invoke the execute() method in the DeleteAction class and so on.

While using links, we can easily form a URL of our choice like,

<c:url var="editURL" value="/Country/Edit">
    <c:param name="countryId" value="${row.countryId}"/>
    <c:param name="currentPage" value="${currentPage}"/>
    <c:param name="countryName" value="${row.countryName}"/>
    <c:param name="countryCode" value="${row.countryCode}"/>
</c:url>

<a href="${editURL}" class="action2"/>

This produces a URL like http://localhost:8080/Assignment/Country/Edit which will call the execute() method in the EditAction class.

How to do the same while using a submit button? Can we have an appropriate URL, when a given submit button is pressed which causes the execute() method in the CreateAction class?

When pressing this submit button, the URL should be

http://localhost:8080/Assignment/Country/Create

The default URL to render an initial page view is like,

http://localhost:8080/Assignment/Country

Can we construct such URLs while making a POST request something similar to those provided by request/action based MVC frameworks (The Struts framework provides an action attribute for a submit button)?

Found this [answer](http://stackoverflow.com/a/11830483/1391249) useful/helpful. More than that is unlikely to exist. — Tiny, Feb 10 '14 at 10:51

score 1 · Accepted Answer · answered Feb 09 '14 at 21:43

1

You can set the URL in the action attribute of the form element. Any button of type submit will post to this URL. Example:

<form action="${editURL}" method="post">
    <button type="submit">Go</button>
</form>

answered Feb 09 '14 at 21:43

David Levesque

22,181
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But there is more than one submit button on the form and the action is different for all of them. So how can we tackle with all of the buttons on the form? (How can we make a different request using different URLs using the `action` attribute of the form?) – Tiny Feb 09 '14 at 21:49
Can't you have multiple forms? Otherwise, you will probably have to use javascript to dynamicaly set the URL. – David Levesque Feb 09 '14 at 21:52
If you have another better alternative then, please don't forget to update the answer. – Tiny Feb 16 '14 at 17:30

score 1 · Answer 2 · edited Feb 16 '14 at 17:32

1

You can use JavaScript function on submit button and set some hidden params in your form and change the values according to your form submission and get the hidden param in your Controller. According to their hidden param values, you can use multiple operations.

Hope It'll help you.

edited Feb 16 '14 at 17:32

Tiny

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answered Feb 10 '14 at 06:30

Arvind Vishwakarma

221
4
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If you have another better alternative then, please don't forget to update the answer. – Tiny Feb 16 '14 at 17:31

Invoking different methods via Servlets depending upon a URL

2 Answers2