FindMonth - A simple Java MVC WebApp using Servlet, JSP, eclipse

In this blog I'll explain with a simple example about creating a Java Web Application using MVC pattern. I'm using a simple java program as model, JSP as view and Servlet as controller. 

This application is developed using eclipse (Juno) IDE,  jdk1.6.0_43 and it is hosted on Apache tomcat 7.0.

What is MVC? 

Here is the definition from Wiki. 

Model–view–controller (MVC) is a software architecture pattern which separates the representation of information from the user's interaction with it.

The model consists of application data, business rules, logic, and functions. 

A view can be any output representation of data, such as a chart or a diagram. Multiple views of the same data are possible, such as a bar chart for management and a tabular view for accountants. The controller mediates input, converting it to commands for the model or view.

FindMonth is my first simple java webapp

How it looks?

Configuration in eclipse

• Open eclipse -> Select Java EE perspective 
• File -> New -> Dynamic Web Project
• Provide ProjectName i.e. FindMonth 
• Select Target run-time has Apache Tomcat 7.0 (or which ever version installed in your computer)
• Click Next -> Next -> Select "Generate web.xml deployment descriptor -> Finish

Project layout in eclipse

The files ticked in RED font are the files created by me for this project.

• NumberToMonth.java acts as Model
• SelectMonth.java is the Servlet
• FindMonth.html is the home page
• result.jsp is the View
• web.xml is a web descriptor file which links the Homepage to Servlet

Code

Model: NumberToMonth.java

I have created a package blog.sliceoffcodes.model which holds the file NumberToMonth.java

• Right click on src (under Java Resources) -> New -> Package -> Provide package name

Create a java file

• Right click on above created package -> New -> Class -> provide name NumberToMonth

package blog.sliceoffcodes.model;

public class NumberToMonth {

int month;

String monthString;

public NumberToMonth(int month) {

super();

this.month = month;

}

public int getMonth() {

return month;

}

public void setMonth(int month) {

this.month = month;

}

public String getMonthString() {

return monthString;

}

private void setMonthString(String monthString) {

this.monthString = monthString;

}

public void FindMonth() {

switch (getMonth()) {

case 1:

setMonthString("January");

break;

case 2:

setMonthString("February");

break;

case 3:

setMonthString("March");

break;

case 4:

setMonthString("April");

break;

case 5:

setMonthString("May");

break;

case 6:

setMonthString("June");

break;

case 7:

setMonthString("July");

break;

case 8:

setMonthString("August");

break;

case 9:

setMonthString("September");

break;

case 10:

setMonthString("October");

break;

case 11:

setMonthString("November");

break;

case 12:

setMonthString("December");

break;

default:

setMonthString("Invalid");

break;

}

}

}

Controller (Servlet): SelectMonth.java

I have created a package blog.sliceoffcodes.web which holds the file SelectMonth.java

• Right click on src (under Java Resources) -> New -> Package -> Provide package name

Create a java file

• Right click on above created package -> New -> Servlet -> provide name SelectMonth.java

package blog.sliceoffcodes.web;

import java.io.IOException;

import java.io.PrintWriter;

import javax.servlet.RequestDispatcher;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import blog.sliceoffcodes.model.NumberToMonth;

public class SelectMonth extends HttpServlet {

private static final long serialVersionUID = 1L;

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

String m = request.getParameter("inputMonth");

/* response.setContentType("text/html");

PrintWriter out = response.getWriter(); 

out.println("Month Input = " + m); */

NumberToMonth nm = new NumberToMonth(Integer.parseInt(m));

nm.FindMonth();

String result = nm.getMonthString();

//out.println("Month output = " + result);

request.setAttribute("monthExtract", result);

RequestDispatcher view = request.getRequestDispatcher("result.jsp");

view.forward(request, response);

}

}

view (Home page): FindMonth.html

• Right click on WebContent -> New -> HTML file -> provide name FindMonth.html

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">

<title>Find Month</title>

</head>

<body>

<h1 align="center">Find Month</h1>

<form method="POST" action="FetchMonth.do">

Select Month Type: <select name="inputMonth" size=1">

<option value="1">1</option>

<option value="2">2</option>

<option value="3">3</option>

<option value="4">4</option>

<option value="5">5</option>

<option value="6">6</option>

<option value="7">7</option>

<option value="8">8</option>

<option value="9">9</option>

<option value="10">10</option>

<option value="11">11</option>

<option value="12">12</option>

</select> <br>

<br>

<center>

<input type="Submit">

</center>

</form>

</body>

</html>

view (jsp): result.jsp

• Right click on WebContent -> New -> JSP file -> provide name result.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"

    pageEncoding="ISO-8859-1"%>

<%@ page import="java.util.*" %>

<html>

<head>

<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">

<title>Result of Month Finder </title>

</head>

<body>

<h1 align="center">Month</h1>

<p>

<%

  String month = (String) request.getAttribute("monthExtract");

  out.print("<b> Month in English: " + month);

  

%>

<br> <br>

<A HREF="FindMonth.html" align="center">HOME</A>

</body>

</html>

web descriptor : web.xml

<?xml version="1.0" encoding="UTF-8"?>

<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">

  <display-name>FindMonth</display-name>

  <welcome-file-list>

    <welcome-file>FindMonth.html</welcome-file>    

  </welcome-file-list>

  

  <servlet>

    <servlet-name>Month</servlet-name>

    <servlet-class>blog.sliceoffcodes.web.SelectMonth</servlet-class>

  </servlet>

  <servlet-mapping>

    <servlet-name>Month</servlet-name>

    <url-pattern>/FetchMonth.do</url-pattern>

  </servlet-mapping>

  

</web-app>