spring aop编程(二)(转载)

前面主要介绍了如何通过xml实现aop编程，下面主要介绍如何通过@AspectJ来实现。
为了使@AspectJ 支持生效,
需要做以下步骤：
在xml中设置

<aop:aspectj-autoproxy/>


或者
在xml中加入
<bean class="org.springframework.aop.aspectj.annotation.AnnotationAwareAspectJAutoProxyCreator" />

声明 aspect

<bean id="myAspect" class="org.xyz.NotVeryUsefulAspect">

<!-- configure properties of aspect here as normal -->

</bean>



package org.xyz;

import org.aspectj.lang.annotation.Aspect;



@Aspect

public class NotVeryUsefulAspect {



}

声明 pointcut


@Pointcut("execution(* transfer(..))")

public void transfer() {}


声明 advice


Before advice:

@Before("com.xyz.myapp.SystemArchitecture.dataAccessOperation()")

public void doAccessCheck() {

// ...

}

After returning advice:

@AfterReturning("com.xyz.myapp.SystemArchitecture.dataAccessOperation()")

public void doAccessCheck() {

// ...

}

或者

@AfterReturning(
pointcut="com.xyz.myapp.SystemArchitecture.dataAccessOperation()",
returning="retVal")

public void doAccessCheck(Object retVal) {

// ...

}

After throwing advice：

@AfterThrowing("SystemArchitecture.dataAccessOperation()")

public void doRecoveryActions() {

// ...

}

或者

@AfterThrowing(

pointcut=" SystemArchitecture.dataAccessOperation()",

throwing="ex")

public void doRecoveryActions(DataAccessException ex) {

// ...

}

After (finally) advice：

@After("com.xyz.myapp.SystemArchitecture.dataAccessOperation()")

public void doReleaseLock() {

// ...

}

Around advice：

@Around("com.xyz.myapp.SystemArchitecture.businessService()")

public Object doBasicProfiling( ProceedingJoinPoint pjp) throws Throwable {

// start stopwatch

Object retVal = pjp.proceed();

// stop stopwatch

return retVal;

}

Advice parameters：

@Before("com.xyz.myapp.SystemArchitecture.dataAccessOperation() &&" + "args(account,..)" )

public void validateAccount(Account account) {

// ...

}

声明参数名称：

@Before(

value="com.xyz.lib.Pointcuts.anyPublicMethod() && " +

"@annotation(auditable)",

argNames="auditable" )

public void audit(Auditable auditable) {

AuditCode code = auditable.value();

// ...

}

Advice 排序：

一般以声明的方法次序为先后

不同的 Advice ，通过实现 Ordered 接口，来排序


Introductions


用于引入新的接口

@Aspect

public class UsageTracking {



@DeclareParents(value="com.xzy.myapp.service.*+",

defaultImpl=DefaultUsageTracked.class)

public static UsageTracked mixin;



@Before("com.xyz.myapp.SystemArchitecture.businessService() &&" +

"this(usageTracked)")

public void recordUsage(UsageTracked usageTracked) {

usageTracked.incrementUseCount();

}



}