This listener is used when we want to know when a attribute has been added in a request, when a attribute has been removed and when it is replaced by another attribute. We can also say that this attribute is used when the developer is interested to be notified when the request attribute changes. Now you may be wondering what is an attribute. An attribute is an object set or you can simply say that it is name/value pair where the name refers to a String and a value refers to the Object.
javax.servlet.ServletRequestAttributeListener interface has following methods:
In the above methods you can see that we have used ServletRequestAttributeEvent class as a parameter to the above methods. This class is a event class which is used for notifications when the changes are made to the attributes of ServletRequest in an application.
The class ServletRequestAttributeEvent has two methods: