Table of Contents
This chapter consists of very short snippets of AspectJ code, typically pointcuts, that are particularly evocative or useful. This section is a work in progress.
Here's an example of how to enfore a rule that code in the java.sql package can only be used from one particular package in your system. This doesn't require any access to code in the java.sql package.
/* Any call to methods or constructors in java.sql */ pointcut restrictedCall(): call(* java.sql.*.*(..)) || call(java.sql.*.new(..)); /* Any code in my system not in the sqlAccess package */ pointcut illegalSource(): within(com.foo..*) && !within(com.foo.sqlAccess.*); declare error: restrictedCall() && illegalSource(): "java.sql package can only be accessed from com.foo.sqlAccess";
Any call to an instance of a subtype of AbstractFacade whose class is not exactly equal to AbstractFacade:
pointcut nonAbstract(AbstractFacade af): call(* *(..)) && target(af) && !if(af.getClass() == AbstractFacade.class);
If AbstractFacade is an abstract class or an interface, then every instance must be of a subtype and you can replace this with:
pointcut nonAbstract(AbstractFacade af): call(* *(..)) && target(af);
Any call to a method which is defined by a subtype of AbstractFacade, but which isn't defined by the type AbstractFacade itself:
pointcut callToUndefinedMethod(): call(* AbstractFacade+.*(..)) && !call(* AbstractFacade.*(..));
The execution of a method that is defined in the source code for a type that is a subtype of AbstractFacade but not in AbstractFacade itself:
pointcut executionOfUndefinedMethod(): execution(* *(..)) && within(AbstractFacade+) && !within(AbstractFacade)
To use a per-class variable declared on many classes, you can defer initialization until you are in a non-static instance context so you can refer to the particular class member. If you want to use it from advice (without knowing the particular class at compile-time), you can declare a method on the type.
aspect Logging { //... /** per-Loggable-class reference to per-class Logger */ static private Logger Loggable+.staticLogger; /** instance getter for static logger (lazy construction) */ public Logger Loggable+.getLogger() { // XXX make private to aspect? if (null == staticLogger) { staticLogger = Logger.getLoggerFor(getClass()); } return staticLogger; } /** when logging and logger enabled, log the target and join point */ before(Loggable loggable) : target(loggable) && logging() { Logger logger = loggable.getLogger(); if (logger.enabled()) { logger.log(loggable + " at " + thisJoinPoint); } } }