Why use ServletContext.setAttribute()?

问题:

Why would we set ServletContext parameters using the setAttribute() method, as we can accomplish the same thing by setting parameters in web.xml and fetching them using getInitParameter()?

回答1:

The servletContext.setAttribute() is dynamic which can be set and reset during runtime.

Where as init-parameter specified in web.xml is static which will not change during the lifetime of application.

Example:

• The database properties like database name configuration propety. It will be mostly configured as context init-param
• And if you want to set property value which derives based on runtime changes, like "last user logged in" or "number of failures" should be context attributes.