Servlet Program in java

Write a servlet that reads the name of the servlet class and its initialisation parameters from a server file and then displays these parameters on the screen.
Packages used:

1.      java.io.*           : Provides for system input and output through data streams, serialization and the file system.

2.      java.util.*        : Provides for system input and output through data streams, serialization and the file system.

3.      javax.servlet.*              : contains a number of classes and interfaces that describe and define the contr acts between a servlet class and the runtime environment provided for an insta nce of such a class by a conforming servlet container.

4.      javax.servlet.http.*      : package contains a number of classes and interfaces that describe and define the contracts between a servlet class running under the HTTP protocol and the runtime environment provided for an instance of such a class by a conforming servlet container.

Classes used:

·         HttpServlet              : simplifies writing HTTP servlets,provides an framework for handling the HTTP protocol. Because it is an abstract class, servlet writers must subclass it and override at least one method.

·         HttpServletRequest : gets data from the client to the servlet for use in the HttpServlet.service method

·         HttpServletResponse  : This interface allows a servlet's service method to manipulate HTTP-protocol specified header information and return data to its client.

·         PrintWriter               : Print formatted representations of objects to a text-output stream. This class implements all of the print methods found in PrintStream

·         HttpUtils                  : collection of static utility methods useful to HTTP servlets.

Logical flow of the program:

·         A public class that inherits HttpServlet is created.

·         Initialisation parameters from a server file is obtained with the help of methods defined in HttpUtils class,object of HttpServletRequest class is used to obtain different parameters of a server file.

Important notes:

·         The servlet program must import the package “javax.servlet.*”.

·         If  the servlet program is accessing database it should import the package “java.sql.*”.

·         The servlet class should be declared “public”.

·         The class should extend “HttpServlet” class.

·         The class should throw ServletException,IOException to avoid compilation error.

·         If  the servlet class is extending “GenericServlet” then the method used is “service()”.

·         If  the servlet class is extending “HttpServlet”, it should import the package “javax.servlet.http.*”.Also the method used here is either “doGet()”  or  “doPost()”.