The Command pattern

- [Instructor] The Command pattern is another one … of these design patterns that exists in the Spring framework … we don't use a lot that are behavior based. … In the Spring framework … there's really two distinct use cases. … First, it's seen with Runnable instances. … Things like the CommandLineRunner, … where you're going to execute a Runnable command … from the base class itself. … The second use case that we see is all the more often seen, … and that's in our MVC layer. … And there's actually an AbstractCommandController … that you can use in Spring MVC … that implements this command pattern. … And the idea here is that in an MVC world, … often you're going to execute these commands against controls, … and you don't want to manipulate the individual controls. … That's going to lead us into what the pattern actually is. … The whole gist of the command pattern is that it provides … an abstraction layer for these request processing scenarios. … Think about a shopping cart. … You have a very common pattern …