MVC Architecture

MVC is an architectural design pattern. 

• Model - business logic.
• View - User Interface
• Controller - handles user input

Why MVC ?

• View is free of any business logic so looks simple and readable.
• Business logic within the model can be reused for more than one views.

Simple example for MVC with JSP

•  A web page for register the student details. 
•  Here Student name, Parent name, Grade, and Address are input 
fields.
•  User can enter these values by clicking "Insert"
•  Here Student name and Grade are mandatory fields.
•  System should validate this fields and show the proper error message.

For this example 

• Create jsp pages for input interface, Error, Success response messages. - view
• Create a java class (Student.java) for a student model - model
• Create a servlet class for redirect a  proper view - controller  

Student Registration page.

When we click "Insert" button after enter all details. 

If we don't enter the Mandatory fields. This error message will display

Mapping a servlet page
Servlets need to be configured ans it needs to be mapped to a URI (URL/URN).
So we have to include the following mapping to the web.xml file.

<servlet>
    <servlet-name>ServletPage</servlet-name>
    <servlet-class>org.ymini.lukshica.controller.ServletPage</servlet-class>
 </servlet>
  
 <servlet-mapping>
    <servlet-name>ServletPage</servlet-name>
    <url-pattern>/Test</url-pattern>
 </servlet-mapping>


Mappings are used by the servlet container to translate a particular request URI to a particular servlet.