从OOP角度分析，我们关注业务的处理逻辑，是属于纵向的行为，从AOP角度分析，我们关注对象行为发生时的问题，是属于横向的行为。
AOP 作用：
1 监控函数的调用
2 捕获异常发生
实际应用在：事务、安全、日志等横切关注。
下面是aop打印service层的方法日志为例：
代码语言：javascript复制/**
* @功能描述: Service层日志/异常切面类
*/
@Component
@Aspect
public class ApiServiceAspect {
private final Logger logger = Logger.getLogger(this.getClass());
/**
* 切面
*/
private final String POINT_CUT =
"execution(* com.demo.bigdata.service.*.*.*(..))";
@Pointcut(POINT_CUT)
private void pointcut(){}
@Before(value = POINT_CUT)
public void before(JoinPoint joinPoint) {
String className = joinPoint.getTarget().getClass().getName();
String methodName = joinPoint.getSignature().getName();
StringBuilder log = new StringBuilder();
log.append("before: ")
.append(className)
.append("@")
.append(methodName)
.append(" , params: ");
Object[] args = joinPoint.getArgs();
for (Object arg : args) {
log.append(JSONObject.toJSONString(arg) ", ");
}
logger.info(log.toString());
}
@AfterReturning(value = "pointcut()", returning = "returnObj")
public void afterReturn(Object returnObj) {
String result = JSONObject.toJSONString(returnObj);
logger.info("afterReturning: " result);
}
@AfterThrowing(value = POINT_CUT, throwing = "e")
public void afterThrowing(Throwable e) {
logger.error("afterThrowing: " e.getMessage(), e);
}
@Around(value = "pointcut()")
public Object around(ProceedingJoinPoint proceedingJoinPoint)
throws Throwable {
Long begin = System.currentTimeMillis();
StringBuilder log = new StringBuilder("around: ");
Object result = null;
try {
result = proceedingJoinPoint.proceed();
} catch (Exception e) {
logger.error(log e.getMessage(), e);
}
Long end = System.currentTimeMillis();
log.append(" 执行时间: ")
.append(end-begin)
.append("ms");
return result;
}
} 配置文件使其生效
<context:component-scan base-package="com.demo.bigdata" />
<aop:aspectj-autoproxy></aop:aspectj-autoproxy>
如果使用了spring mvc后，如果把<aop:aspectj-autoproxy proxy-target-class="true"/>放在application.xml文件中可能会aop无效，最好把它放在dispatcher-servlet.xml文件中。
