Tiny MVC for J2EE

account.jsp

Howdy, ${user.name}!

AccountAction.java

public class AccountAction implements Action
{

    @Override
    public void process(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
        //do your processing here, take values from DB, may be!
        SomeBean user = new SomeBean("Paddy")
		
        //Very important. we are setting attribute to the request and forwarding that request.
        // forward will keep the request intact unlike redirect!
        request.setAttribute("user", user);
        ServletContext context = request.getSession().getServletContext();
        context.getRequestDispatcher("/WEB-INF/users/account.jsp").forward(request, response);	
    }
}

Action.java

public interface Action
{
    public void process(HttpServletRequest request, HttpServletResponse response) 
                    throws ServletException, IOException;
}

FrontController.java

package com.myapp;

public class FrontController extends HttpServlet{

    private Map<String, Action> actions = new HashMap<String, Action>();
    
    public void init()
    {
        this.actions.put("/account.do", new AccountAction());
    }
    
    public void takeAction(HttpServletRequest  request, HttpServletResponse response) 
            throws ServletException, IOException
    {

        String reqUri = request.getRequestURI();

        Action action = (Action)actions.get(reqUri);

        action.process(request, response);
    }
    
    public void doPost(HttpServletRequest  request, HttpServletResponse response) throws ServletException, IOException
    {
        takeAction(request, response);
    }

    public void doGet(HttpServletRequest  request, HttpServletResponse response) throws ServletException, IOException
    {
        takeAction(request, response);
    }
    
}

web.xml

<servlet>
    <servlet-name>FrontController</servlet-name>
    <servlet-class>com.myapp.FrontController</servlet-class>
</servlet>

<servlet-mapping>
    <servlet-name>FrontController</servlet-name>
    <url-pattern>*.do</url-pattern>
</servlet-mapping>