编程式动态AOP实践

在实际开发中我们经常需要打印日志或者监控方法执行,使用 spring ao 能够很好的实现这个功能,但是切面中的 Pointcut 是固定值,不可被更改,就导致多个应用程序使用功能相同的 aop 需要有大量重复代码,我们希望将这些功能相同的部分封装并抽离为一个公共组件包,能够动态配置 Pointcut 。

实现思路

从Spring的AOP机制已知，要对一个方法或类切入需要实现以下步骤

• Pointcut ,实现 spring 中的 Pointcut 接口自定已切入点,根据具体的业务实现

  本文章示例使用 spring 中的 AspectJExpressionPointcut 实现

• Advisor ，它可以扩展 Spring 中 AbstractBeanFactoryPointcutAdvisor

• MethodInterceptor , 在此接口中实现拦截逻辑

• 实例化注入到 spring 容器

具体实践

DynamicPointcutAdvisor 动态切入点

public class DynamicPointcutAdvisor extends AbstractBeanFactoryPointcutAdvisor {
    /**
     * 表达式
     */
    private String expression;

    public DynamicPointcutAdvisor(String expression) {
        this.expression = expression;
    }

    public Pointcut aspectJExpressionPointcut() {
        AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();
        pointcut.setExpression(this.expression);
        return pointcut;
    }

    @Override
    public Pointcut getPointcut() {
        return aspectJExpressionPointcut();
    }

}
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DynamicMethodInterceptor 动态方法拦截

@Slf4j
public class DynamicMethodInterceptor implements MethodInterceptor {
    @Override
    public Object invoke(MethodInvocation invocation) throws Throwable {
        long startTime = System.currentTimeMillis();
        Object ret;
        JSONObject rest = new JSONObject();
        ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
        HttpServletRequest request = attributes.getRequest();
        try {
            UserAgent userAgent = UserAgent.parseUserAgentString(request.getHeader("User-Agent"));
            rest.put("RequestUrl", request.getRequestURL().toString());
            rest.put("RequestType", request.getMethod());
            rest.put("RequestHeader", RequestUtils.getHeadersInfo(request));
            rest.put("RequestMethod", invocation.getMethod().getName());
            rest.put("RequestParams", invocation.getArguments());
            rest.put("ServerAddr", StrFormatter.format("{}{}{}{}{}", request.getScheme(), "://", request.getServerName(), ":", request.getServerPort()));
            rest.put("RemoteAddr", RequestUtils.getRemoteAddr(request));
            rest.put("Browser", userAgent.getBrowser().toString());
            rest.put("BrowserVersion", userAgent.getBrowserVersion());
            rest.put("operatingSystem", userAgent.getOperatingSystem().toString());
            rest.put("requestTime", LocalDateTime.now());
            ret = invocation.proceed();
            rest.put("responseResult", ret);
        } catch (Throwable throwable) {
            rest.put("ExceptionName", throwable.getClass().getName());
            rest.put("ExceptionMessage", throwable.getMessage());
            JSONObject e = new JSONObject();
            e.put("ExceptionName", throwable.getClass().getName());
            e.put("ExceptionMessage", throwable.getMessage());
            log.error(e.toString());
            throw throwable;
        } finally {
            rest.put("Time", System.currentTimeMillis() - startTime);
            log.info(rest.toString());
        }
        return ret;
    }
}

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DynamicAdvisorConfiguration 实例化

@Configuration
@ConditionalOnProperty(name = "log.dynamic.pointcut.expression")
public class DynamicAdvisorConfiguration {
    @Value("${log.dynamic.pointcut.expression:}")
    private String expression;

    @Bean(name = "dynamicPointcutAdvisor")
    @Role(BeanDefinition.ROLE_INFRASTRUCTURE)
    public DynamicPointcutAdvisor adapterServiceAdvisor() {
        DynamicPointcutAdvisor advisor = new DynamicPointcutAdvisor(expression);
        advisor.setAdviceBeanName("dynamicPointcutAdvisor");
        advisor.setAdvice(new DynamicMethodInterceptor());
        advisor.setOrder(Ordered.HIGHEST_PRECEDENCE);
        return advisor;
    }

}
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配置文件 application.properties

log.dynamic.pointcut.expression=execution(public * com.devin.dynamic.controller..*.*(..))
log.dynamic.pointcut.expression=true
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结果

[nio-9000-exec-2] c.s.s.a.d.DynamicMethodInterceptor       : {"responseResult":{"code":200,"message":"16003908714631539353"},"RequestMethod":"dynamicNumber","RequestUrl":"http://localhost:9000/dynamic/number","ServerAddr":"http://localhost:9000","Time":52,"RemoteAddr":"0:0:0:0:0:0:0:1","operatingSystem":"WINDOWS_10","RequestParams":[],"requestTime":"2020-03-25T11:26:10.344","RequestHeader":{"accept-language":"zh-CN,en-US;q=0.7,en;q=0.3","host":"localhost:9000","upgrade-insecure-requests":"1","connection":"keep-alive","accept-encoding":"gzip, deflate","user-agent":"Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:74.0) Gecko/20100101 Firefox/74.0","accept":"text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8"},"BrowserVersion":{"majorVersion":"74","minorVersion":"0","version":"74.0"},"RequestType":"GET","Browser":"FIREFOX7"}
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拓展 Pointcut

spring 默认有一些切入点的实现,我们只需要实例化就可以了

但是对于不满足我们需求的可以通过实现 Pointcut 接口实现。

package org.springframework.aop;

public interface Pointcut {
    Pointcut TRUE = TruePointcut.INSTANCE;
    ClassFilter getClassFilter();
    MethodMatcher getMethodMatcher();
}

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其他的请自行探索。