AspectJ Language
info
Anatomy
1 aspect FaultHandler {
2
3 private boolean Server.disabled = false;
4
5 private void reportFault() {
6 System.out.println("Failure! Please fix it.");
7 }
8
9 public static void fixServer(Server s) {
10 s.disabled = false;
11 }
12
13 pointcut services(Server s): target(s) && call(public * *(..));
14
15 before(Server s): services(s) {
16 if (s.disabled) throw new DisabledException();
17 }
18
19 after(Server s) throwing (FaultException e): services(s) {
20 s.disabled = true;
21 reportFault();
22 }
23 }
| Term | Definition |
|---|---|
| Pointcut | Picks out join points (points in execution of prg) |
| Advice | Brings tgt pointcut and body of code to define aspect implementation |
Examples
| Scenario | Syntax |
|---|---|
| particular method body execution | execution(void Point.setX(int)) |
| method is called | call(void Point.setX(int)) |
| exception handler executed | handler(ArrayOutOfBoundsException) |
object executing is of someType | this(SomeType) |
executing code belongs to SomeClass | within(SomeClass) |
join point in control flow of call to a Test's no-argument main | cflow(call(void Test.main())) |
Composing pointcuts
| Description | Syntax |
|---|---|
Any call to int method on Point instance regardless of name | target(Point) && call(int *()) |
Any call to any method where the call is made from within Point or Line | call(* *(..)) && (within(Line) || within(Point)) |
| execution of any constructor taking exactly one int argument regardless of where call is from | within(*) && execution(*.new(int)) |
any method call to int method when executing object is any type except Point | !this(Point) && call(int *(..)) |
Wildcards
| Description | Syntax |
|---|---|
| Execution of any method regardless of return / parameter type | execution(* *(..)) |
Call to any set method regardless of return / parameter type | call(* set(..)) |
Based on Constructors / Modifiers
| Description | Syntax |
|---|---|
| call to any public method | call(public * *(..)) |
| execution of non-static method | execution(!static * *(..))` |
| any execution of public non static method | execution(public !static * *(..)) |
any call to method in MyInterface's signature | call(* MyInterface.*(..)) |
Call Vs Execution
note
When methods and constructors run, there are 2 times associated - when they are called / when they actually execute
call pointcuts | execution pointcuts |
|---|---|
| enclosing code is that of call site i.e. call(void m()) && withincode(void m()) will only capture directly recursive calls | enclosing code is the method itself i.e. execution(void m()) && withincode(void m()) == execution(void m()) |
| does not capture super calls to non static methods | |
| use when targeting when a particular signature is called | use when actual peice of code runs |
Pointcut Compositions
- Use primitive pointcuts to build more powerful pointcuts