需要增强的服务

假如有以下service,他的功能很简单,打印输入的参数并返回参数。

@Service
public class SimpleService {
    public String getName(String name) {
        System.out.println(get name is:  + name);
        return name;
    }
} 

定义切面和切点

@Component
@Aspect
public class L
ogAspect {
    // 定义切点
    @Pointcut(within(com.ydoing.service..*))
    // @Pointcut(execution(* com.ydoing.service.*.*(..)))
    public void pointCut() {
    } 
}

Before增强处理

    // 定义Before增强处理
    // 在目标方法调用之前执行增强处理
    @Before(pointCut())
    public void before(JoinPoint jp) {
        // 获取连接点传入参数
        // Object args = jp.getArgs();
        System.out.println(Before增强处理--execute before target method call);
    } 

测试输出:

Before增强处理--execute before target method call
get name is: Bob

AfterReturning增强

    // 在目标方法调用之后执行增强处理
    @AfterReturning(pointcut = pointCut(), returning = ret)
    public void afterReturning(JoinPoint jp, Object ret) {
        System.out.println(AfterReturnin增强处理--execute after target method call, return value is : + ret);
    }

测试输出:

get name is: Bob
AfterReturnin增强处理--execute after target method call, return value is :Bob

Around增强

    @Around(pointCut())
    public void around(ProceedingJoinPoint jp) {
        System.out.println(Around增强--around start...);
        Object[] args = jp.getArgs();

        // 修改目标方法传入的参数
        args[0] = around_add_ + args[0];
        try {
            System.out.println(修改传入参数后执行输出:);
            jp.proceed(args);
        } catch (Throwable e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        System.out.println(Around增强--around end);
    }

输出:

Around增强--around start...
修改传入参数后执行输出:
get name is: around_add_Bob
Around增强--around end

After增强

    // 无论是否发生异常都会 处理
    @After(pointCut())
    public void after() {
        System.out.println(After增强--always do no matter what happen);
    }

输出:

get name is: Bob
After增强--always do no matter what happen  

AfterThrowing增强

    @AfterThrowing(pointcut = pointCut(), throwing = ex)
    public void afterThrowing(JoinPoint jp, Throwable ex) {
        System.out.println(error is:  + ex);
    }

这里没抛异常,就没有输出了

测试代码如下

@Configuration
@EnableAspectJAutoProxy
@ComponentScan(basePackages = com.ydoing.service,com.ydoing.ect)
public class AppConfig {
    public static void main(String[] args) {
        @SuppressWarnings(resource)
        ApplicationContext ctx = new AnnotationConfigApplicationContext(AppConfig.class);
        SimpleService service = ctx.getBean(SimpleService.class);
        service.getName(Bob);
    }
}