Pointcut expressions: execution, within, bean, args, @annotation.

A pointcut is an expression that selects which joinpoints an advice applies to. In Spring AOP a joinpoint is always a method execution, so a pointcut answers "on which method calls does this advice run?" Spring borrows AspectJ's pointcut grammar; the designators you must know are execution, within, bean, args, @annotation, and @within.

execution — the workhorse

Matches method executions by signature. The pattern is execution(modifiers? return-type declaring-type.method(params) throws?).

// any public method in the service package and sub-packages, any args
@Pointcut("execution(* com.example.service..*.*(..))")

// methods named find* returning a List, exactly one arg
execution(java.util.List com.example..*.find*(*))

* is a single wildcard, .. means "zero or more" (packages or parameters). This is the most precise and most common designator.

within — by type/package

Coarser: matches any joinpoint inside the given type or package, ignoring the signature.

@Pointcut("within(com.example.repository..*)")   // all methods of all classes there

bean — by bean name

Spring-specific (not in plain AspectJ). Matches by the bean's id, with wildcards.

@Pointcut("bean(*Service)")        // every bean whose name ends in "Service"

args — by argument types

Selects on the runtime argument types, and can bind them for the advice.

@Before("execution(* *..*(..)) && args(id)")
public void log(Long id) { ... }   // fires when the single arg is a Long, binds it

@annotation and @within — by annotation

@annotation(X) matches methods annotated with X; @within(X) matches methods of a class annotated with X.

@Around("@annotation(com.example.Audited)")        // method carries @Audited
@Around("@within(org.springframework.stereotype.Service)")  // class is @Service

@annotation is the idiom behind custom marker annotations — define @Audited, advise @annotation(Audited), done.

Combining and reusing

Combine with &&, ||, !, and name reusable pointcuts with @Pointcut:

@Pointcut("within(com.example.service..*)")
public void inService() {}

@Around("inService() && @annotation(Retryable)")
public Object retry(ProceedingJoinPoint pjp) throws Throwable { ... }