Pointcut Expressions
Imagine you are a security guard and you have been told: "Check everyone who enters through the main door between 9 AM and 5 PM." This is a pointcut expression – it specifies exactly which joinpoints to target.
In Spring AOP, pointcut expressions use AspectJ syntax. The most common is execution().
Execution Expression Syntax:
execution(modifiers-pattern? return-type-pattern declaring-type-pattern? method-name-pattern(param-pattern) throws-pattern?)Here are practical examples:
// Any public method in any class
@Before("execution(public * *(..))")
// Any method in com.example.service package
@Before("execution(* com.example.service.*.*(..))")
// Any method that starts with 'get'
@Before("execution(* get*(..))")
// Any method that takes a String parameter
@Before("execution(* *(String))")
// Any method in BankService class regardless of parameters
@Before("execution(* com.example.service.BankService.*(..))")
// Any method with any number of parameters
@Before("execution(* *(..))")
Other pointcut designators:
- within() – limits to certain types.
@Before("within(com.example.service.*)") - args() – matches on argument types.
@Before("args(String, int)") - @annotation() – matches methods with a specific annotation.
@Before("@annotation(org.springframework.transaction.annotation.Transactional)") - bean() – matches specific Spring bean name.
@Before("bean(myService)")
You can combine expressions with &&, ||, ! :
@Before("execution(* com.example.service.*.*(..)) && args(name,age)")
public void adviceWithArgs(String name, int age) {
System.out.println("Name: " + name + ", Age: " + age);
}
Two Minute Drill
- Pointcut expression selects which joinpoints to apply advice.
- Most common is execution() with pattern matching.
- Use within() for type matching, args() for parameters.
- @annotation() matches methods with specific annotations.
- Combine expressions with &&, ||, ! for precise control.
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