Java web applications are dynamic web applications developed using Java technologies. They are commonly used for creating enterprise-level applications that require scalability, security, and robust performance.
To begin, ensure that you have the following installed:
Example: Verify your JDK installation using the command:
javac -version
The output should display your Java compiler version.
Open your IDE and create a new "Dynamic Web Project". This project type is designed for Java web applications.
For example, in Eclipse:
A servlet is a Java class used to handle HTTP requests and responses.
Example: Create a servlet that outputs "Hello, World!"
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
public class HelloWorldServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<html><body>");
out.println("<h1>Hello, World!</h1>");
out.println("</body></html>");
}
}
Save this file in the src folder of your project.
The web.xml file maps a URL pattern to your servlet.
Example configuration:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee" version="3.0">
<servlet>
<servlet-name>HelloWorldServlet</servlet-name>
<servlet-class>HelloWorldServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>HelloWorldServlet</servlet-name>
<url-pattern>/hello</url-pattern>
</servlet-mapping>
</web-app>
Deploy your application on a server like Apache Tomcat.
For example:
http://localhost:8080/MyFirstWebApp/hello.You should see "Hello, World!" displayed in your browser.
This article introduced the basics of Java web applications in Advanced Java. We set up the environment, created a servlet, configured deployment, and ran the application. These concepts form the foundation for building complex enterprise web applications.