Servlet Life Cycle (Explained with Example and Diagram)

Servlets are integral components of Java web development, managing client requests and dynamically generating content. Within the web server's architecture, servlets adhere to a defined life cycle, playing a pivotal role in web technology.

web server with a web container containing servlets

Why Servlets?

Servlets offer several advantages, making them a preferred choice for building dynamic web applications:

Portability: Servlets are written in Java, ensuring platform independence. This allows them to run on any platform that supports Java.

Robustness: Leveraging Java's strong typing and exception handling, servlets enhance the robustness of web applications, making them less prone to errors.

Performance: Servlets run within the server's address space, resulting in efficient resource utilization and faster response times compared to other server-side technologies.

Scalability: Servlets can handle multiple requests concurrently, enabling scalable web applications that can accommodate growing user traffic.

Integration: Servlets seamlessly integrate with other Java EE technologies, such as JavaServer Pages (JSP), Enterprise JavaBeans (EJB), and Java Database Connectivity (JDBC), facilitating the development of complex web solutions.

Servlet Life Cycle

Understanding the life cycle of servlet in Java is paramount for proficient web development. The sequence of stage initialization, service, and destruction dictates the behavior of servlets within a web container.

Initialization Phase

During the initialization phase of the servlet life cycle in Java, the servlet container loads the servlet class and calls its init() method. This method is invoked only once during the servlet's lifecycle and is used for initialization tasks such as setting up database connections or initializing resources.

Example:

Loading...
 Run

Service Phase

The service phase is where the servlet handles client requests. Upon receiving a request, the servlet container invokes the service() method of the servlet. This method is responsible for processing the request, generating a response, and sending it back to the client. It is invoked for each request received by the servlet.

Example:

Loading...
 Run

Destruction Phase

In the destruction phase of the servlet life cycle, the servlet container removes the servlet from memory. This occurs when the servlet container decides to shut down or when it needs to reclaim memory. Before destroying the servlet, the container calls the destroy() method, allowing the servlet to perform cleanup tasks such as closing database connections or releasing resources.

Example:

Loading...
 Run

Servlet Life Cycle Architecture

Understanding the architecture of the servlet life cycle is crucial for web developers. The life cycle of servlet in Java consists of the following stages:

1. Loading and Instantiation: The servlet container loads the servlet class and creates an instance of the servlet.

2. Initialization: The container calls the init() method to initialize the servlet.

3. Service: The container invokes the service() method to handle client requests.

4. Destruction: The container calls the destroy() method before removing the servlet from memory.

Servlet Life Cycle Diagram

Servlet Implementation

Below is a simple example demonstrating servlet implementation:

Loading...
 Run

Explore our Web Development Course and test your skills with our new Online Java Compiler!

Conclusion

Understanding the life cycle of a servlet in Java is essential for creating robust, efficient, and scalable web applications. By comprehending the phases of initialization, service, and destruction, developers can effectively manage resources and optimize the performance of their web applications. The servlet life cycle in web technology plays a critical role in ensuring that applications run smoothly and efficiently.