AOP注解式拦截

1. 自己定义的拦截注解

package com.spring.aop;

import java.lang.annotation.Documented;
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.ANNOTATION_TYPE,ElementType.METHOD,ElementType.TYPE})
@Documented
public @interface MyAction {

    String value();
}

2. 定义aop切点

package com.spring.aop;

import java.lang.reflect.Method;

import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.stereotype.Component;

@Aspect
@Component
public class MyAop {

    //切点切入自己配置的那个注解MyAction
    @Pointcut("@annotation(com.spring.aop.MyAction)") //注意这里的写法
    public void annotationPointCat(){}

    @Before("annotationPointCat()")//位置为这个包下的所有类、所有方法、不论参数是什么类型
    public void before(JoinPoint joinPoint){
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        Method method = signature.getMethod();
        MyAction myAction =  method.getAnnotation(MyAction.class);
        System.out.println("before: "+myAction.value());
    }

    @After("annotationPointCat()")
    public void after(JoinPoint joinPoint){
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        Method method = signature.getMethod();
        MyAction myAction =  method.getAnnotation(MyAction.class);
        System.out.println("after: "+myAction.value());
    }
}

3. 编写服务类，应用切面

package com.spring.aop;

import org.springframework.stereotype.Component;

@Component
public class MyServer {　　/*　　显而易见，利用注解式拦截，会提高切面的复用率　　*/

    @MyAction("ser01")
    public void ser01(){
        System.out.println("call ser01");
    }

    @MyAction("ser02")
    public void ser02(){
        System.out.println("call ser02");
    }
}

4. Spring配置文件（APP.xml）<context:component-scan base-package="com.spring.aop"></context:component-scan>

     <!-- 使 AspectJ 的注解起作用 ； autoproxy自动代理-->
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>

5. 运行   

 public static void main(String[] args) {
        BeanFactory factory = new ClassPathXmlApplicationContext("com/spring/ioc/APP.xml");
        MyServer myServer = factory.getBean(MyServer.class);
        myServer.ser01();

        myServer.ser02();
 }

依赖jar包    <!-- Spring -->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${org.springframework-version}</version>
            <exclusions>
                <!-- Exclude Commons Logging in favor of SLF4j -->
                <exclusion>
                    <groupId>commons-logging</groupId>
                    <artifactId>commons-logging</artifactId>
                 </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${org.springframework-version}</version>
        </dependency>

        <!-- AspectJ -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjrt</artifactId>
            <version>${org.aspectj-version}</version>
        </dependency>
     <!-- https://mvnrepository.com/artifact/org.aspectj/aspectjweaver -->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>${org.aspectj-version}</version>
        </dependency>

异常：Caused by: java.lang.NoClassDefFoundError: org/aspectj/weaver/reflect/ReflectionWorld$ReflectionWorldException

是因为缺少 aspectjweaver 包