详解spring中aop不生效的几种解决办法

时间：2020-12-12 09:27:18|栏目：JAVA代码|点击：次

先看下这个问题的背景：假设有一个spring应用，开发人员希望自定义一个注解@Log，可以加到指定的方法上，实现自动记录日志(入参、出参、响应耗时这些)

package com.cnblogs.yjmyzz.springbootdemo.aspect;
 
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
 
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface Log {
 
}

然后再写一个Aspect来解析这个注解，对打了Log注解的方法进行增强处理　

package com.cnblogs.yjmyzz.springbootdemo.aspect;
 
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;
 
import java.lang.reflect.Method;
 
@Component
@Aspect
public class LogAspect {
 
  @Pointcut("execution (* com.cnblogs.yjmyzz.springbootdemo.service..*.*(..))")
  public void logPointcut() {
 
  }
 
  @Around("logPointcut()")
  public void around(JoinPoint point) {
    String methodName = point.getSignature().getName();
    Object[] args = point.getArgs();
    Class<?>[] argTypes = new Class[point.getArgs().length];
    for (int i = 0; i < args.length; i++) {
      argTypes[i] = args[i].getClass();
    }
    Method method = null;
    try {
      method = point.getTarget().getClass().getMethod(methodName, argTypes);
    } catch (Exception e) {
      e.printStackTrace();
    }
    //获取方法上的注解
    Log log = method.getAnnotation(Log.class);
    if (log != null) {
      //演示方法执行前，记录一行日志
      System.out.println("before:" + methodName);
    }
    try {
      //执行方法
      ((ProceedingJoinPoint) point).proceed();
    } catch (Throwable throwable) {
      throwable.printStackTrace();
    } finally {
      if (log != null) {
        //演示方法执行后，记录一行日志
        System.out.println("after:" + methodName);
      }
    }
  }
}

写一个测试Service类：

package com.cnblogs.yjmyzz.springbootdemo.service;
 
import com.cnblogs.yjmyzz.springbootdemo.aspect.Log;
import org.springframework.stereotype.Component;
 
@Component
public class HelloService {
   
  @Log
  public void sayHi(String msg) {
    System.out.println("\tsayHi:" + msg);
  }
 
  public void anotherSayHi(String msg) {
    this.sayHi(msg);
  }
 
}

最后来跑一把：

package com.cnblogs.yjmyzz.springbootdemo;
 
import com.cnblogs.yjmyzz.springbootdemo.service.HelloService;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;
 
/**
 * @author 菩提树下的杨过
 */
@ComponentScan("com.cnblogs.yjmyzz")
@Configuration
@EnableAspectJAutoProxy
public class SampleApplication {
 
  public static void main(String[] args) {
    AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(SampleApplication.class);
    HelloService helloService = context.getBean(HelloService.class);
    helloService.sayHi("hi-1");
    System.out.println("\n");
    helloService.anotherSayHi("hi-2");
  }
}

输出如下：