使用spring的MethodInterceptor实现aop功能的三种方式

如果对于spring MethodInterceptor或spring aop概念不清楚，参考：spring aop, spring interceptor, springmvc interceptor有什么区别？

以下是在spring boot环境下执行的

在spring boot下有两种方式设置AOP（实现织入weave）：

1. 使用@Aspect注解

2. 使用DefaultPointcutAdvisor

以实现TracingInterceptor为例

方法1：使用aspectj execution（切点） + interceptor（增强Advice）构成织入（DefaultPointcutAdvisor）

interceptor

class TracingInterceptor implements MethodInterceptor {
  Object invoke(MethodInvocation i) throws Throwable {
    System.out.println("method "+i.getMethod()+" is called on "+
                       i.getThis()+" with args "+i.getArguments());
    Object ret=i.proceed();
    System.out.println("method "+i.getMethod()+" returns "+ret);
    return ret;
  }
}

织入配置类

@Configuration
public class InterceptorConfig {

    public static final String traceExecution = "execution(* com.hfi.aop..*.*(..))";


    @Bean
    public DefaultPointcutAdvisor defaultPointcutAdvisor2() {
        TracingInterceptor interceptor = new TracingInterceptor();
        AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();
        pointcut.setExpression(traceExecution);

        // 配置增强类advisor
        DefaultPointcutAdvisor advisor = new DefaultPointcutAdvisor();
        advisor.setPointcut(pointcut);
        advisor.setAdvice(interceptor);
        return advisor;
    }
}

效果：当执行到com.hfi.aop包下的方法，当执行performEncore方法

可以看到我们配置的TracingInterceptor生效了

方法2：使用自定义注解（切点）+interceptor（增强Advice）构成织入（DefaultPointcutAdvisor）

自定义注解HfiTrace

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface HfiTrace {
}

interceptor

public class TracingInterceptor implements MethodInterceptor {
    @Override
    public Object invoke(MethodInvocation invocation) throws Throwable {
        Method method = invocation.getMethod();
        HfiTrace annotation = getAnnotation(method);
        if (annotation == null) {
            return invocation.proceed();
        }
        // 为什么调用http://127.0.0.1:8089/jpademo/perform时有两次输出呢？
        // 因为在Audience里面用的是@Around，会拦截到两次
        System.out.println("method " + invocation.getMethod() + " is called on " + invocation.getThis() + " with args" +
                " " + invocation.getArguments());
        Object proceed = invocation.proceed();
        System.out.println("method " + invocation.getMethod() + " returns " + proceed);
        return proceed;
    }

    private HfiTrace getAnnotation(Method method) {
        // 如果有多个annotation 似乎就不好用了 如放在controller上 由于已经有了@RequestMapping注解了 所以...
        if (method.isAnnotationPresent(HfiTrace.class)) {
            return method.getAnnotation(HfiTrace.class);
        }
        return null;
    }
}

织入配置类

@Configuration
public class InterceptorAnnotationConfig {

    @Bean
    public DefaultPointcutAdvisor defaultPointcutAdvisor3() {
        TracingInterceptor interceptor = new TracingInterceptor();

        // AnnotationMatchingPointcut pointcut = new AnnotationMatchingPointcut(HfiTrace.class, true);
        JdkRegexpMethodPointcut pointcut = new JdkRegexpMethodPointcut();
        pointcut.setPatterns("com.hfi.*");

        // 配置增强类advisor
        DefaultPointcutAdvisor advisor = new DefaultPointcutAdvisor();
        advisor.setPointcut(pointcut);
        advisor.setAdvice(interceptor);
        return advisor;
    }
}

业务代码

    @HfiTrace
    @Override
    public String perform() {
        System.out.println("perform...");
        return "perform";
    }

效果：

可以看到执行也是生效的

方法3：使用自定义注解（切点）+@Aspect（切面）构成织入

自定义注解HfiTrace

@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface HfiTrace {
    String name() default "默认注解信息";
}

织入配置类

@Component
@Aspect
public class TracingAspect {
    @Before("@annotation(test)")
    public void beforeTest(JoinPoint point, HfiTrace test){
        System.out.println("method " + point.getSignature().getName() + " is called on " + point.getThis() + " with " +
                "args" +
                " " + point.getArgs());
        System.out.println("before invoke: "+ test.name());
    }

    @AfterReturning(value = "@annotation(test)", returning = "rvt")
    public void afterTest(JoinPoint point, HfiTrace test, Object rvt) {
        System.out.println("method "+point.getSignature().getName() + " returns " + rvt);
        System.out.println("after invoke: " + test.name());
    }
}

业务代码：

controller层：

    @HfiTrace
    @GetMapping("/perform")
    public String perform() {
        String perform = performance.perform();
        return perform;
    }

    @HfiTrace(name = "abc")
    @GetMapping("/performEncore")
    public String performEncore() {
        // 强制转换
        Encoreable encoreable = (Encoreable) performance;
        return encoreable.performEncore();
    }

service层：

@Component
public class PerformanceImpl implements Performance {

    @HfiTrace
    @Override
    public String perform() {
        System.out.println("perform...");
        return "perform";
    }
}

效果：

综上：三种方式都可以实现相同的功能，方法3看起来最为简洁，只需要定义一个注解，然后写一个@Aspect切面类，就可以拦截指定方法的运行了

源代码：https://gitee.com/constfafa/spring_springboot_learning/tree/master/methodinterceptor-demo