基于注解的AOP实现

╰+哭是因爲堅強的太久メ 2022-06-12 00:16 168阅读 0赞

在web项目中有很多的AOP是基于路径来拦截的，但是有些情况下项目的API路径是多种多样的，而且需要被拦截做AOP的API也是杂七乱八的，那这种情况下，我们基于包路径的AOP的能力就会觉着很无力。曾经我使用的是黑白名单的功能支持。但是后来发现这种方案代价也挺高的。下面我简单介绍下基于配置注解的AOP拦截，这中实现方案，对我上文讲述的问题的支持能力个人感觉真是太好了。  
首先创建一个注解

package org.demo.annotations;
    
    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 DemoPermission {
        String[] demo() default {};
    
    }

基于当前注解实现AOP

package org.demo;
    
    import java.lang.annotation.Annotation;
    import java.util.HashMap;
    import java.util.Map;
    
    import org.aspectj.lang.JoinPoint;
    import org.aspectj.lang.ProceedingJoinPoint;
    import org.aspectj.lang.annotation.After;
    import org.aspectj.lang.annotation.Around;
    import org.aspectj.lang.annotation.Aspect;
    import org.aspectj.lang.annotation.Before;
    import org.aspectj.lang.reflect.MethodSignature;
    import org.demo.annotations.DemoPermission;
    import org.demo.controller.DemoFactory;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Component;
    
    @Aspect
    @Component
    public class CopyOfPermissionAspect {
    
        @Autowired(required = false)
        DemoFactory demoFactory;
    
        @Before("@annotation(org.demo.annotations.DemoPermission)")
        public void before(JoinPoint caller) {
            Map<String, Object> functionParamValueMap = getFunctionParamValueMap(caller);
            DemoPermission annotation = getAnnotation(caller, DemoPermission.class);
            System.out.println("before-->" + annotation);
        }
    
        @After("@annotation(org.demo.annotations.DemoPermission)")
        public void after(JoinPoint caller) {
            DemoPermission annotation = getAnnotation(caller, DemoPermission.class);
            System.out.println("after-->" + annotation);
    
        }
    
        @Around("@annotation(org.demo.annotations.DemoPermission)")
        public Object around(ProceedingJoinPoint pjp) {
            DemoPermission annotation = getAnnotation(pjp, DemoPermission.class);
            System.out.println("around-->" + annotation);
            Object proceed = null;
            try {
                proceed = pjp.proceed();
            } catch (Throwable e) {
            }
            return proceed;
        }
    
    
        private <T extends Annotation> T getAnnotation(JoinPoint caller,
                Class<T> annotationClass) {
            if (caller.getSignature() instanceof MethodSignature) {
                MethodSignature methodSignature = (MethodSignature) caller
                        .getSignature();
                return methodSignature.getMethod().getAnnotation(annotationClass);
            }
            return null;
        }
    
        private Map<String, Object> getFunctionParamValueMap(JoinPoint caller) {
            Map<String, Object> result = new HashMap<>();
            if (caller.getSignature() instanceof MethodSignature) {
                Object[] paramsValues = caller.getArgs();
                MethodSignature methodSignature = (MethodSignature) caller
                        .getSignature();
                String[] paramNames = methodSignature.getParameterNames();
                for (int i = 0, len = paramNames.length; i < len; i++) { 
                    String paramName = paramNames[i];
                    Object paramValue = paramsValues[i];
                    result.put(paramName, paramValue);
                }
            }
            return result;
        }
    }

然后使用注解测试下功能

package org.demo.controller;
    
    import org.demo.annotations.DemoAspect;
    
    import org.demo.annotations.DemoPermission;
    import org.springframework.web.bind.annotation.RequestMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    @RestController
    public class DemoController {
    
        @DemoPermission
        @RequestMapping("/demo")
        public String demo(String name) {
            System.out.println("demo--->" + name);
            return "demo";
        }
    
    }

这个是一个最简单是实现demo，在此基础上我们可以做更多的扩展和支持。详细的扩展代码就不在此一一列出了。  
　　[更多代码请访问GitHub][GitHub]

[GitHub]: https://github.com/xupeng001/demo-parents