SpringAOP应用-日志输出耗时统计
一、采用@AspectJ注解来实现
1、在Spring配置文件中启用AspectJ：<aop:aspectj-autoproxy />。同时需要在应用程序的classpath中引入两个AspectJ库：aspectjweaver.jar 和 aspectjrt.jar。
2、定义用到的切面（@Aspect）类：包含切点（@Pointcut）和通知。
注：A可以单独定义切点，然后通过切点的引用来定义通知；也可以使用一个in-place 的切入点表达式直接定义通知。
B通知的参数
3、在Spring配置文件中，配置切面Bean。（切记在配置文件中配置Abject类）
示例：配置部分
<aop:aspectj-autoproxy /> <bean id="logAdviceAspect" class="com.aspects.LogAdviceAspect"> </bean>
Bean部分示例：
@Aspect
public class LogAdviceAspect {
private static Logger log = Logger.getLogger(LogAdviceAspect.class);
@Around("execution(* test.TestStruts.*(..))")
public Object doBasicProfilingTime(ProceedingJoinPoint pjp) throws Throwable {
log.debug("Takes: start........... ");
//org.apache.commons.lang.time.StopWatch
StopWatch clock = new StopWatch();
clock.start(); // 计时开始
Object retVal = pjp.proceed();
clock.stop(); // 计时结束
log.debug("Takes:" + clock.getTime() + " ms ");
return retVal;
}
}
二、采用基于模式（schema-based）的方式来实现
1、定义用到的日志或者时间计算类：主要包含相应通知对应的实现方法。
2、在Spring配置文件中，配置步骤1中的Bean。
3、在Spring配置文件中，配置AOP信息。
示例：配置部分
<aop:config> <aop:aspect id="test" ref="timeAdvice"> <aop:pointcut id="idempotentOperation" expression="execution(* test.TestStruts.*(..))" /> <aop:around pointcut-ref="idempotentOperation" method="doBasicProfilingTime" /> </aop:aspect> </aop:config> <bean id="timeAdvice" class="com.aspects.TestAspect"> </bean>
Bean部分示例：
public class TestAspect {
protected final Log log = LogFactory.getLog(this.getClass());
public Object doBasicProfilingTime(ProceedingJoinPoint pjp) throws Throwable {
//org.apache.commons.lang.time.StopWatch
StopWatch clock = new StopWatch();
clock.start(); // 计时开始
Object retVal = pjp.proceed();
clock.stop(); // 计时结束
log.debug("Takes:" + clock.getTime() + " ms ");
return retVal;
}
}
三、采用基于模式（schema-based）和Interceptor的方式来实现
1、定义用到的日志或者时间计算类：该类实现Interceptor接口。
2、在Spring配置文件中，配置步骤1中的Bean。
3、在Spring配置文件中，配置AOP信息。
示例：配置部分
<aop:config> <aop:advisor id="methodTimeLog" advice-ref="methodTimeAdvice" pointcut="execution(* *..service..*(..))" /> </aop:config> <bean id="methodTimeAdvice" class="com.aspects.MethodTimeAdvice" />
Bean部分示例：
public class MethodTimeAdvice implements MethodInterceptor {
protected final Log log = LogFactory.getLog(MethodTimeAdvice.class);
public Object invoke(MethodInvocation invocation) throws Throwable {
// 用 commons-lang 提供的 StopWatch 计时
StopWatch clock = new StopWatch();
clock.start(); // 计时开始
Object result = invocation.proceed();
clock.stop(); // 计时结束
// 方法参数类型，转换成简单类型
Class[] params = invocation.getMethod().getParameterTypes();
String[] simpleParams = new String[params.length];
for (int i = 0; i < params.length; i++) {
simpleParams[i] = params[i].getSimpleName();
}
log.debug("Takes:" + clock.getTime() + " ms ["
+ invocation.getThis().getClass().getName() + "."
+ invocation.getMethod().getName() + "("
+ StringUtils.join(simpleParams, ",") + ")] ");
return result;
}
}
注：几种通知需要实现的Interceptor接口分别为：
1、Around通知：org.aopalliance.intercept.MethodInterceptor
2、Before通知：org.springframework.aop.MethodBeforeAdvice
3、AfterReturning通知：org.springframework.aop.AfterReturningAdvice
4、AfterThrowing通知：org.springframework.aop.ThrowsAdvice
附录A：遇到异常
java.lang.NoClassDefFoundError:org/objectweb/asm/commons/EmptyVisitor
解决办法是：
1.去掉类路径上的关于Hibernate的3个lib
asm.jar
asm-attrs.jar
cglib-2.1.3.jar
2.加入Spring中的以下4个lib
asm-2.2.2.jar
asm-commons-2.2.2.jar
asm-util-2.2.2.jar
cglib-nodep-2.1_3.jar
异常分析详见：http://royboy.iteye.com/blog/142449
附录B：常见的切入点（pointcut）定义（参阅：spring2.0-reference_final_zh_cn.chm）
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
@Aspect
public class SystemArchitecture {
/**
* A join point is in the web layer if the method is defined
* in a type in the com.xyz.someapp.web package or any sub-package
* under that.
*/
@Pointcut("within(com.xyz.someapp.web..*)")
public void inWebLayer() {}
/**
* A join point is in the service layer if the method is defined
* in a type in the com.xyz.someapp.service package or any sub-package
* under that.
*/
@Pointcut("within(com.xyz.someapp.service..*)")
public void inServiceLayer() {}
/**
* A join point is in the data access layer if the method is defined
* in a type in the com.xyz.someapp.dao package or any sub-package
* under that.
*/
@Pointcut("within(com.xyz.someapp.dao..*)")
public void inDataAccessLayer() {}
/**
* A business service is the execution of any method defined on a service
* interface. This definition assumes that interfaces are placed in the
* "service" package, and that implementation types are in sub-packages.
*
* If you group service interfaces by functional area (for example,
* in packages com.xyz.someapp.abc.service and com.xyz.def.service) then
* the pointcut expression "execution(* com.xyz.someapp..service.*.*(..))"
* could be used instead.
*/
@Pointcut("execution(* com.xyz.someapp.service.*.*(..))")
public void businessService() {}
/**
* A data access operation is the execution of any method defined on a
* dao interface. This definition assumes that interfaces are placed in the
* "dao" package, and that implementation types are in sub-packages.
*/
@Pointcut("execution(* com.xyz.someapp.dao.*.*(..))")
public void dataAccessOperation() {}
}
常见切入点表达式的例子：
1、任意公共方法的执行：execution(public * *(..))
2、任何一个以“set”开始的方法的执行：execution(* set*(..))
3、AccountService 接口的任意方法的执行：
execution(* com.xyz.service.AccountService.*(..))
4、定义在service包里的任意方法的执行：execution(* com.xyz.service.*.*(..))
5、定义在service包或者子包里的任意方法的执行：
execution(* com.xyz.service..*.*(..))
6、在service包里的任意连接点（在Spring AOP中只是方法执行）：
within(com.xyz.service.*)
7、在service包或者子包里的任意连接点（在Spring AOP中只是方法执行）：
within(com.xyz.service..*)