MethodsFilter

Methodsfilter, often written as MethodsFilter or described as a filtering component, is a software mechanism used to select or prune a set of methods from a class or interface based on defined criteria. It provides a filtering layer for reflection, proxy generation, remote procedure calls, and aspect-oriented programming to determine which methods are subject to inspection, invocation, or interception.

Typically, a methods filter is implemented as a predicate or interface with a method such as accept or shouldInvoke that takes a Method object and, in some designs, contextual information like the target instance or arguments. Implementations express criteria such as method name patterns, visibility (public, protected), return type, parameter types, annotations, or security and access requirements. Filters can be composed or chained to form a broader policy.

Common applications include restricting dynamic proxies to only certain methods for security reasons, selecting methods to be advised by aspects, or limiting RPC exposure to a subset of service methods. In development tooling, method filtering helps enumerate methods that meet criteria for code generation, testing, or documentation.

Relation to other concepts: a methods filter is related to method interception and reflection utilities and is a design pattern used across frameworks. It is not a universal language construct, but a conceptual tool that frameworks implement to manage method exposure and behavior.

Examples of filters include a PublicMethodFilter, an AnnotatedMethodFilter, a NamePatternFilter, and a CombinedFilter. By providing pluggable filters, frameworks can adapt method exposure and behavior without hardcoded rules.