Filters are actually features in .NET, after .net.35 we can add some feature to the class or method name, and in the .NET mvc environment, there are several more important features, such as HonorizeAttribute
It is mainly in the permission verification, sometimes we are used to call it "filter", the reason is that it can filter out the users who do not meet the requirements, hehe, the following is the code of the common user rights filter in the system, for everyone to learn