Java EE 8 Design Patterns and Best Practices

Implementing commands

Here, we have the abstract class AbstractCommand, which includes the abstract execute method. All implementations of this command extend AbstractCommand, which is an abstract class:

package com.rhuan.action.Command;import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public abstract class AbstractCommand {    public abstract void execute(HttpServletRequest                                 request, HttpServletResponse response)            throws ServletException, java.io.IOException ;}

In the following block of code, we have the PdfCommand class. This is a subclass of AbstractCommand that implements the logic to download a PDF file:

import javax.servlet.ServletException;import javax.servlet.http.HttpServletRequest ...