IOC principle - Servlet Container Vs Spring IOC container

IOC can be implemented, using either:

• Dependency Injection

• Service locator pattern

---

Spring IOC container follow IOC principle using Dependency injection, where implementations can be injected at runtime as constructor-based or setter-based

Servlet container(Ex: Apache tomcat) follow IOC principle to pick servlet class implementation based on the configured data given in web.xml with url pattern matching rules.

---

The purpose of both containers differ. But,

What design pattern does servlet container follow to implement IOC principle?