Tech-Notes

Spring AOP

Aspects of programming means cross cutting concerns.

Note: we should use @EnableAspectJAutoProxy before @Configuration file. <aop:aspectj-autoproxy> in xml config file

Defination

Aspect: class which define pointcuts and advices
Advice: behaviour that executes at join point. Join point : argument value of the aop method Pointcut: expression language of AOP that matches join points, enable reuse of pointcut

@Aspect - declare class

Advice

Advice represents an action taken by an aspect at a particular join point.

Types of Advice:

1. @Before - run before method.
2. @After - run after method.
3. @AfterReturning - run after method(if success). void afterReturningMethod(Object result)
4. @AfterThrowing - run after method(if exception). void afterThrowingMethod(Exception ex)
5. @Around - run after and before method (using joinpoint.proceed()). void aroundMethod(ProceedingJoinPoint jp)

@Aspect
@Component
public class AOPsample {
  @Around("execution(public void org.controller.display())")
  void aroundMethod(ProceedingJoinPoint jp){
    Object[] args = jp.getArgs();
    sysout("before execution of function");
    Object result = jp.proceed(args);   //method executes
    sysout("after execution of function");
  }
}

@Pointcut

expression language of AOP that matches join points, enable reuse of pointcut

@Pointcut("execution(public void org.controller.display())")
void reuseMethod(){}
@Before("reuseMethod()")
void methodName2(){
}
@Before("reuseMethod()")
void methodName3(){
}

@Order

gives order of execution to aspect class

Access method details.

public void display(JointPoint jointPoint){
  MethodSignature methodSig = (MethodSignature) jointPoint.getSignature();
  Object[] args = joinPoint.getArgs();  //get arguements 
}

LOGGER.

 private Logger log = Logger.getLogger(getClass().getName());
 log.info("log message");
 log.fatal("log message");
 log.debug("log message");
 log.error("log message");
 log.warn("log message");
 log.trace("log message");

Spring security.

1. Create SecurityWebApplicationInitializer.java.

   public class SecurityWebApplicationInitializer extends AbstractSecurityWebApplicationInitializer {
   }
   

2. create SecurityConfig.java.

   @Configuration
   @EnableWebSecurity
   public class DemoSecurityConfig extends WebSecurityConfigurerAdapter {	
    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        auth.inMemoryAuthentication().withUser("john").password("secret123").roles("EMPLOYEE");
        auth.inMemoryAuthentication().withUser("mary").password("secret123").roles("MANAGER");
     }
   }