高级Spring之切点匹配

女爷i 2024-03-27 11:06 83阅读 0赞

#### 演示 - 切点匹配 ####

public class A16 {
        public static void main(String[] args) throws NoSuchMethodException {
    //        AspectJExpressionPointcut pt1 = new AspectJExpressionPointcut();
    //        pt1.setExpression("execution(* bar())");
    //        System.out.println(pt1.matches(T1.class.getMethod("foo"), T1.class));
    //        System.out.println(pt1.matches(T1.class.getMethod("bar"), T1.class));
    //
    //        AspectJExpressionPointcut pt2 = new AspectJExpressionPointcut();
              //切点表达式
    //        pt2.setExpression("@annotation(org.springframework.transaction.annotation.Transactional)");
    //        System.out.println(pt2.matches(T1.class.getMethod("foo"), T1.class));
    //        System.out.println(pt2.matches(T1.class.getMethod("bar"), T1.class));
    
           //抽象父类
            StaticMethodMatcherPointcut pt3 = new StaticMethodMatcherPointcut() {
                @Override
                public boolean matches(Method method, Class<?> targetClass) {
                    // 检查方法上是否加了 Transactional 注解
                    MergedAnnotations annotations = MergedAnnotations.from(method);
                    if (annotations.isPresent(Transactional.class)) {
                        return true;
                    }
                    // 查看类上是否加了 Transactional 注解
                    annotations = MergedAnnotations.from(targetClass, MergedAnnotations.SearchStrategy.TYPE_HIERARCHY);
                    if (annotations.isPresent(Transactional.class)) {
                        return true;
                    }
                    return false;
                }
            };
    
            System.out.println(pt3.matches(T1.class.getMethod("foo"), T1.class));
            System.out.println(pt3.matches(T1.class.getMethod("bar"), T1.class));
            System.out.println(pt3.matches(T2.class.getMethod("foo"), T2.class));
            System.out.println(pt3.matches(T3.class.getMethod("foo"), T3.class));
        }
    
    
        static class T1 {
            @Transactional
            public void foo() {
            }
            public void bar() {
            }
        }
    
        @Transactional
        static class T2 {
            public void foo() {
            }
        }
    
        @Transactional
        interface I3 {
            void foo();
        }
        static class T3 implements I3 {
            public void foo() {
            }
        }
    }

学到了什么  
a. 底层切点实现是如何匹配的: 调用了 aspectj 的匹配方法  
b. 比较关键的是它实现了 MethodMatcher 接口, 用来执行方法的匹配