We know that using ServletContext, we can create an attribute with application scope that all other servlets can access but we can initialize ServletContext init parameters as String only in the deployment descriptor (web.xml). What if our application is database-oriented and we want to set an attribute in ServletContext for Database Connection.
If your application has a single entry point (user login), then you can do it in the first servlet request but if we have multiple entry points then doing it everywhere will result in a lot of code redundancy. Also if the database is down or not configured properly, we won’t know until the first client request comes to the server. To handle these scenarios, servlet API provides Listener interfaces that we can implement and configure to listen to an event and do certain operations.
