spring aop编程(二)

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();
}

}

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