Developing software and web applications requires technical as well as experiential knowledge. The Spring framework is a top choice among developers, students, and researchers to program java-based apps. So, let us look at some instances of Java MVC projects and get familiar with some nuts and bolts of the development process.
The Model-View-Controller (MVC) architecture is a type of design that separates your application into three logical components with each one handling a specific aspect. The framework enjoys industry-wide acceptance in the development of scalable projects. By studying a Spring MVC example, you would learn how to implement the MVC pattern and create an application with a stellar user interface. So, let’s begin with getting acquainted with the design pattern first.
Background of MVC
As the name suggests, the MVC architecture comprises three layers of code, namely:
- Model: Data storage, integrity, consistency, and queries (Data-related source code)
- View: Input validation, view updation, and model modification (UI-related source code)
- Controller: Presentation of code and assets (Back-end code)
You can develop, control, and debug these layers separately. Moreover, the three segments do not interfere with one another, and you can hide the data access layer from the users. Therefore, it is a boon for handling complex requirements in a lightweight and uncomplicated fashion. You can attempt a simple Hello World application or a full-fledged enterprise application with this framework.
Spring Web Application Example
Beginners must note that an IDE environment setup would be required to write the code and manage the necessary libraries. Once you finish that task, you can continue working on your Spring MVC example. To implement the pattern, you would first need to create three different Model, View, and Controller packages. You can start by creating the three sections, merging them into a single application, and finally running the app. Here is a step-by-step explanation of the process:
1. Creating the Model
‘Model’ is that part of your application that contains the data and provides the same to the app. It also updates the data on the disk upon receiving a call from the Controller. Firstly, you have to create a package and name it. You can name it JavaMVCModels.
You would then create a new class file (called HelloWorldModel) under this package to act as the Model for your application. Hence, the class name and file name would be similar. Next, you would extract the data from the source and save/update the user data. Using File APIs of Java documentations can make the entire exercise easier to implement.
2. Creating the View
For this part, you can either use Eclipse IDE or NetBeans. The View segment of your application shows what the Controller allows. In Eclipse, you would have to write the code, whereas NetBeans comes with drag-and-drop functionality to implement a simple GUI.
The procedure for creating View is quite similar to the practice adopted under Model. You would begin by creating a new package, JavaMVCViews, followed by a class called HelloWorldView.
3. Creating the Controller
The Controller is perhaps the most vital segment of the MVC application as it contains the logic for the Model-View interaction. To construct the Controller, you would repeat the same process of creating a package and a class. In this case, you can name them JavaMVCControllers and HelloWorldController, respectively. The Controller includes three main functions. These methods are described below.
- startApplication: It starts the application by calling the View ( In Java’s Swing API, you set the setVisible property as true to make the JFrame visible)
- Extract data from Model
- Return data to View
4. Running the application
As explained above, you can trigger startApplication to run your web MVC app. When the user wants to transmit or receive the data, the Controller responds by asking or sending the data from the Model. After that, the Controller sends the result (success or error) back to the View. View also operated via the Controller, inquiring about the data or adding it to the Model. Finally, the Controller validates the data for updation by the Model.
Now, let’s see how these steps would unfold in a Spring MVC example. Our project involves a user registration and login system that uses Maven for dependencies management and the Eclipse setup. You can use this tutorial as a guide for practicing your Spring MVC development skills.
Step 1: Create a Maven Project
It is relatively straightforward to create a Maven project in Eclipse. You can do so by selecting Web Archetype. Open your IDE and go to File>New>Others. Then, select Maven Project>Next. You would need to uncheck the Default Workspace Location and click on Browse to set up your own workspace. Next, choose an archetype, specify the Group Id and Artifact Id, and click on Finish.
Step 2: Update Maven dependencies
Now, open the pom.xml file from your newly created Maven project folder. Update the POM to modify the default structure. You may also have to add dependencies by updating the XML file with the latest Junit and saving it.
Step 3: Create a web.xml file
This step would include the functioning of two key root servlets:
- DispatcherServlet: To redirect application requests to the appropriate Controller for specific URLs
- mvc-spring: A root container that the Spring container would look for
Step 4: Create a Spring configuration
You would need an XML file to enable spring configuration, say, spring-mvc-servlet.xml. At this stage, it would also be required to create the beans.
Step 5: Create separate Controllers for user registration and user login
In this project, you would have to create two controller packages, i.e., jbr.springmvc.controller and jbr.springmvc.model.
Step 6: Create classes for accessing the MySQL database
This step is about making DAO classes or an interface that lets you access the MySQL database. You can do so by writing the code for a package called jbr.springmvc.dao.
Step 7: Create a new Spring beans configuration
Go to ‘resources’ and create a new xml bean configuration to define the beans. You can name it user-beans.xml.
Step 8: Create MySQL tables
This step consists of constructing a database table with columns and rows to structure the data. Here, you would start your code with the CREATE TABLE statement.
Step 9: Create Views
To create Views, you would work with the /src/main/webapp folder, beginning by creating home.jsp. Then, under the /src/main/webapp/jsp, you would write code for creating register.jsp, login.jsp, and welcome.jsp.
Step 10: Run the application
Right-click on the application and follow the instructions in the sequence given below:
- Run as>Run on server>Run using Tomcat
You would be able to see the output of your Spring web application example in the form of the following pages:
- User Registration
- User Registration Success
- Login Success
The MVC connection follows that the data comes down from the data source to view via the Controller. Further, the data rendered by View is displayed on the screen. Spring MVC applications have several advantages, from providing robust configuration and rapid development to being faster to debug, test, and reuse. Creating a classic Hello World application using this design pattern can demonstrate the intricacies of development to aspiring software developers.
Technology careers call for continuous learning, knowledge expansion, and skill enhancement. And project activities offer an excellent way to expand your capabilities. We hope that you would have learned something new with the above demonstration of Java MVC projects.
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