关于springboot:SpringBoot基础之AOPAspectJ

日志切面，其中execution中能够革新为@Before(“execution( (..))”)，第一个代表返回类型，第二个代表办法名，括号中的点代表数个参数
JoinPoint能够获取到执行的办法名称。@Before(“execution( hello())”)示意带有一个任何类型并且返回参数不限的hello办法

@Component
@Aspect
public class TracingAspect {
    Logger logger = Logger.getLogger("...");
    //执行办法前能够截获，能够控制程序不进入办法
    @Before("execution(void doSomething())")
    //@Before("execution(* *(..))")
    public void entering(JoinPoint joinPoint){
        logger.info("entering method"+joinPoint.getStaticPart().getSignature().toString());
    }
    //执行办法后能够截获，能够获取到后果，异样等
    @After("execution(* *(..))")
    public void exiting(JoinPoint joinPoint){
        logger.info("existing "+joinPoint.getSignature());
        for(Object org:joinPoint.getArgs())
            logger.info("Arg: "+org);
    }
    //捕捉异样
    @AfterThrowing(pointcut = "execution(void throwsRuntimeException())", throwing = "ex")
    public void logException(RuntimeException ex){
        logger.info("Exception:" + ex);
    }
    //捕捉返回后果
    @AfterReturning(pointcut = "execution(* *(..))", returning = "string")
    public void logResult(String string){
        logger.info("result:" + string);
    }
    //同时反对进入办法前，执行办法后，捕捉异样，捕捉返回后果
    @Around("execution(* *(..))")
    public Object trace(ProceedingJoinPoint proceedingJoinPoint) throws Throwable{
        String methodInformation = proceedingJoinPoint.getStaticPart().getSignature().toString();
        logger.info("Entering:"+methodInformation);
        try{
            return proceedingJoinPoint.proceed();
        }catch(Throwable ex){
            logger.info("Exception in:"+methodInformation + ex);
            throw  ex;
        }finally {
            logger.info("Exiting "+methodInformation);
        }
    }
}

execution( (..))示意同一个package门路下

//能够在execution中写好相对的类名办法名称也可
execution(int com.test.Service.hello(int))
//通过符号替换相应的信息，其中..示意任何子包 
execution(* com.test..*Service.*(..))

如果须要截取带注解的

//必须是带办法注解的
@Around("execution(@annotation.Trace * *(..))")
//必须是带类注解的
@Around("execution(* (@org.springframework.stereotype.Repository *).*(..))")

如果须要截取带注解的类

@Around("bean(*Service)")
@Around("bean(*)")

通过或者来多减少不同的截取

execution(* service.*.*(..))||execution(* repository.*.*(..))

Pointcut能够替换原有的

@Around("bean(*Service)")
//下面与上面的等价
package com.pluralsight.mypointcuts;
public class MyPointCusts {
    @Pointcut("bean(*Service)")
    public void beanNamePointcust(){}
    //示意类注解截获
    @Pointcut("execution(* (@org.springframework.stereotype.Repository *).*(..))")
    public void Repository(){}
}
@Around("com.pluralsight.mypointcuts.MyPointCusts.beanNamePointcust()")

容许AspectJ动静加载EnableLoadTimeWeaving

@Configuration
@ComponentScan(basePackages = "com.pluralsight")
@EnableLoadTimeWeaving
public class SystemConfiguration {
}

还有很多Spring曾经定义好的Interceptor
CustomizableTraceInterceptor可自定义跟踪输入
SimpleTraceInterceptor获取根本信息
DebugInterceptor获取残缺信息
PerformanceMonitorInterceptor应用StopWatch的Spring应用累，可用于测量性能，能够准确到毫秒级，实用于数据
AsyncExecutionInterceptor容许异步办法调用，能够应用这个拦截器而不必应用异步，并且办法将有后盾中的其余线程执行
ConcurrencyThrottleInterceptor能够限度对象中的线程数，理论能够设置并执行的线程数
CatchInterceptor容许缓存办法的调用后果，不须要编写本人的缓存

重试机制

@Around("execution(* com.pluralsight..*Service.*(..))")
public Object retry(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
    try {
        return proceedingJoinPoint.proceed();
    } catch (Throwable ex) {
        return proceedingJoinPoint.proceed();
    }
}

熔断机制，当申请CircuitBreaker的办法时，如果能够失常返回不做解决，因为counter就是0，能够间接执行
然而当获取到异样时，设置counter值为1，这样下一次再来申请则不会调用CircuitBreaker的办法，只会减少counter的值，并判断
直到counter的值为10，则调用CircuitBreaker的办法，如果胜利设置counter为0能够持续调用，如果异样同样设置counter为1，再循环10次

@Component
@Aspect("perthis(com.pluralsight.aspect.CircuitBreakerAspect.circuitBreakerMethods())")
public class CircuitBreakerAspect {
    @Pointcut("execution(@com.pluralsight.aspect.CircuitBreaker * *(..))")
    public void circuitBreakerMethods(){}
    private AtomicInteger counter = new AtomicInteger();
    private Throwable throwable;
    @Around("com.pluralsight.aspect.CircuitBreakerAspect.circuitBreakerMethods()")
    public Object retry(ProceedingJoinPoint proceedingJoinPoint) throws Throwable{
        try{
            if(counter.get() == 0){
                return proceedingJoinPoint.proceed();
            }
            if(counter.incrementAndGet() == 10) {
                Object result = proceedingJoinPoint.proceed();
                counter.set(0);
                return result;
            }
        }catch(Throwable throwable){
            this.throwable = throwable;
            counter.set(1);
        }
        throw this.throwable;
    }
}