MVC In JSP

MVC is known as Model View and Controller. It is a layout sample that separates the business logic, presentation logic, and data.

The controller acts as an interface among View and Model. Controller intercepts all of the incoming requests.

The model represents the state of the software i.e. data. It also can have business logic.

View act for the presentation that is UI(User Interface).

Benefits of MVC (Model 2) Architecture:

1. Navigation authority is centralized
2. Easy to handle the big application

Note: If you are new to MVC then please refer MVC Model 1 and MVC Model 2 the proceeding

MVC Example in JSP

In this example, we're making the use of servlet as a controller, jsp as a view component, Java Bean class as a model.

In this example, we've produced five pages:

• index.jsp a page that receives input from the user.
• ControllerServlet.java a servlet that acts as a controller.
• login-success.jsp and login-error.jsp files act as view components.
• web.xml record for mapping the servlet.

File: index.jsp

<form action="ControllerServlet" method="post">  
Name:<input type="text" name="name"><br>  
Password:<input type="password" name="password"><br>  
<input type="submit" value="login">  
</form>

File: ControllerServlet

package com.javatpoint;  
import java.io.IOException;  
import java.io.PrintWriter;  
import javax.servlet.RequestDispatcher;  
import javax.servlet.ServletException;  
import javax.servlet.http.HttpServlet;  
import javax.servlet.http.HttpServletRequest;  
import javax.servlet.http.HttpServletResponse;  
public class ControllerServlet extends HttpServlet {  
    protected void doPost(HttpServletRequest request, HttpServletResponse response)  
            throws ServletException, IOException {  
        response.setContentType("text/html");  
        PrintWriter out=response.getWriter();  
        
        String name=request.getParameter("name");  
        String password=request.getParameter("password");  

        LoginBean bean=new LoginBean();  
        bean.setName(name);  
        bean.setPassword(password);  
        request.setAttribute("bean",bean);  
          
        boolean status=bean.validate();  
          
        if(status){  
            RequestDispatcher rd=request.getRequestDispatcher("login-success.jsp");  
            rd.forward(request, response);  
        }  
        else{  
            RequestDispatcher rd=request.getRequestDispatcher("login-error.jsp");  
            rd.forward(request, response);  
        }  

    }  

    @Override  
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)  
            throws ServletException, IOException {  
        doPost(req, resp);  
    }  
}  

File: LoginBean.java

package com.javatpoint;  
public class LoginBean {  
private String name,password;  

public String getName() {  
    return name;  
}  
public void setName(String name) {  
    this.name = name;  
}  
public String getPassword() {  
    return password;  
}  
public void setPassword(String password) {  
    this.password = password;  
}  
public boolean validate(){  
    if(password.equals("admin")){  
        return true;  
    }  
    else{  
        return false;  
    }  
}  
}  

File: login-success.jsp

<%@page import="com.javatpoint.LoginBean"%>  
<p>You are successfully logged in!</p>  
<%  
LoginBean bean=(LoginBean)request.getAttribute("bean");  
out.print("Welcome, "+bean.getName());  
%>  

File: login-error.jsp

<p>Sorry! username or password error</p>  
<%@ include file="index.jsp" %>

File: 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">  
    
  <servlet>  
  <servlet-name>s1</servlet-name>  
  <servlet-class>com.javatpoint.ControllerServlet</servlet-class>  
  </servlet>  
  <servlet-mapping>  
  <servlet-name>s1</servlet-name>  
  <url-pattern>/ControllerServlet</url-pattern>  
  </servlet-mapping>  
</web-app>  

download this example (developed using eclipse IDE)

Output