How do you create a Java application using Java EE?

Table of Contents

• Introduction
• Steps to Create a Java EE Application
  • 1. Setting Up the Environment
  • 2. Create a Java EE Project
    • Eclipse IDE:
    • IntelliJ IDEA:
  • 3. Create a Servlet
    • Step-by-Step Servlet Creation:
  • 4. Deploy and Run the Application
• Practical Examples of Java EE Components
  • Example 1: Adding a JSP Page
  • Example 2: Handling Form Data
• Conclusion

Introduction

Java EE (now referred to as Jakarta EE) is a platform designed for building large-scale, distributed, and scalable enterprise applications. It provides a set of specifications and libraries for developing web-based, multi-tier applications. A Java EE application typically consists of web components (like servlets and JSPs), business logic, and a persistent data layer. In this guide, we will walk through the process of creating a Java EE application, from setting up the environment to developing a simple web application.

Steps to Create a Java EE Application

1. Setting Up the Environment

To start building a Java EE application, you need to set up your development environment with the following tools:

• Java Development Kit (JDK): Download and install the latest version of the JDK from Oracle's website.
• Java EE Application Server: You need an application server that supports Java EE, such as:
  • Apache Tomcat: A lightweight server often used for testing.
  • WildFly: A full-featured Java EE application server.
  • GlassFish: Another widely used Java EE server.
• Integrated Development Environment (IDE): Use a Java IDE like Eclipse or IntelliJ IDEA with built-in support for Java EE development.

2. Create a Java EE Project

Most Java IDEs have built-in support for creating Java EE projects.

Eclipse IDE:

1. Open Eclipse and navigate to File > New > Dynamic Web Project.
2. Enter a project name, e.g., "MyJavaEEApp".
3. Set the target runtime to your application server (Tomcat, WildFly, etc.).
4. Choose the Dynamic web module version (e.g., Servlet 3.1).
5. Finish the setup to create the project.

IntelliJ IDEA:

1. Go to File > New > Project.
2. Select Java Enterprise under project type.
3. Choose the JavaEE version and configure the server (Tomcat, WildFly, etc.).
4. Click Next to create the project.

3. Create a Servlet

In a Java EE application, servlets are a common way to handle HTTP requests. Let’s create a simple servlet to display a "Hello World" message.

Step-by-Step Servlet Creation:

1. Create a Servlet Class: In your project’s src folder, create a new servlet class by extending HttpServlet.

2. Deploy the Servlet: The @WebServlet("/hello") annotation maps this servlet to the URL http://localhost:8080/MyJavaEEApp/hello.
3. Configure **web.xml**: (optional) If you want to configure servlets in the web.xml deployment descriptor instead of using annotations:

4. Deploy and Run the Application

1. Build the Project: Use your IDE’s build tools or an external build tool like Maven or Gradle to compile your Java EE project.
2. Deploy to Server: Right-click your project and select Run As > Run on Server in Eclipse or deploy it manually to your application server (e.g., by copying the .war file to the webapps folder in Tomcat).
3. Test the Application: Open your browser and go to http://localhost:8080/MyJavaEEApp/hello to see the "Hello, Java EE World!" message.

Practical Examples of Java EE Components

Example 1: Adding a JSP Page

You can use JSP (JavaServer Pages) for rendering dynamic content in your Java EE application.

1. Create a welcome.jsp file in the WebContent folder:

2. Modify the web.xml to map a URL to the JSP page:

Now, visiting http://localhost:8080/MyJavaEEApp/ will display the JSP page.

Example 2: Handling Form Data

1. Create an HTML form in your JSP page:

2. Create a new servlet to handle form submissions:

When the form is submitted, the FormServlet will process the request and display the user's name.

Conclusion

Building a Java EE application involves setting up the environment, creating dynamic web components like servlets and JSPs, and deploying the application to a Java EE-compliant server. With a structured environment and the power of Java EE, you can create robust, scalable, and maintainable enterprise applications. By using tools like Eclipse or IntelliJ IDEA, you can streamline development and focus on building the business logic for your web applications.