CS 318 - Week 9 Lab - Intro to Java Servlets

Java abstract class - like in C++,
*   implements an abstract concept,
    meant to serve JUST as a superclass for subclasses;

    HttpServlet is an abstract class.

    To create our Java servlets,
    we'll create subclasses of this abstract class

    public class St10HelloWorld13 extends HttpServlet

*   the packages containing Java servlet-related classes
    are:

    javax.servlet
    javax.servlet.http

    so, we'll have:

    import javax.servlet.*;
    import javax.servlet.http.*;

*   within your Java servlet,
    you are most likely going to implement method(s)
    doGet and/or doPost

    The appropriate one of these two methods 
    is called by the web server when a request
    for this servlet comes in.

    (if the request's method is post, web server
    calls doPost --
    if the request's method is get, web server
    calls doGet)

    *   the web server packages the request's data
        into an object, an HttpServletRequest object
        which is one of the arguments to doGet, doPost

    *   (typically) the servlet tends to output
        to an output stream that is related to 
        doGet's and doPost's second parameter,
        an HttpServletResponse object

        ...and the web server returns the resulting
	HttpServletResponse (so streamed into)
	to the browser/client/presentation tier

    public class St10HelloWorld13 extends HttpServlet   
    {
        public void doGet(HttpServletRequest request,
                          HttpServletResponse response)
                         throws ServletException, IOException
        {
            ...
        }

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

*   the request object has a method,
    getParameter

    ...called with the String containing the name
    of a form element,

    and it returns a String, a String version of
    the value of that element from the request
    (from the submitted form)

*   see examples!
    St10HelloWorld13.java
    St10EmpSal.java