在练习用AOP增强方法。
工程目录：

package com.witacm.springframework.aop;

import org.springframework.stereotype.Component;

@Component
public class StudentDAO {
    public void say(){
        System.out.println("I am StudentDAO.");
    }
}

package com.witacm.springframework.aop;

import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.springframework.stereotype.Component;

@Component
@Aspect
public class StudentProxy {
    @Before(value = "execution(* com.witacm.springframework.aop.StudentDAO.say())")
    public void sayProxy()
    {
        System.out.println("Proxy.");
    }
}

package com.witacm.springframework;

import com.witacm.springframework.aop.StudentDAO;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringFrameworkDemo0 {
    public static void main(String[] args) {
        ApplicationContext context=new ClassPathXmlApplicationContext("bean4.xml");
        StudentDAO student=context.getBean("studentDAO",StudentDAO.class);
        student.say();
    }
}

<!-- bean4.xml -->
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
                            http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
                            http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
    <context:component-scan base-package="com.witacm.springframework.aop"></context:component-scan>
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>

</beans>

报错：

Exception in thread "main" org.springframework.beans.factory.BeanDefinitionStoreException: Failed to read candidate component class: file [D:\Javaweb\SpringFramework\out\production\SpringFramework\com\witacm\springframework\aop\StudentDAO.class]; nested exception is org.springframework.core.NestedIOException: ASM ClassReader failed to parse class file - probably due to a new Java class file version that isn't supported yet: file [D:\Javaweb\SpringFramework\out\production\SpringFramework\com\witacm\springframework\aop\StudentDAO.class]; nested exception is java.lang.IllegalArgumentException: Unsupported class file major version 61
    at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.scanCandidateComponents(ClassPathScanningCandidateComponentProvider.java:452)
    at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.findCandidateComponents(ClassPathScanningCandidateComponentProvider.java:315)
    at org.springframework.context.annotation.ClassPathBeanDefinitionScanner.doScan(ClassPathBeanDefinitionScanner.java:276)
    at org.springframework.context.annotation.ComponentScanBeanDefinitionParser.parse(ComponentScanBeanDefinitionParser.java:90)
    at org.springframework.beans.factory.xml.NamespaceHandlerSupport.parse(NamespaceHandlerSupport.java:74)
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1391)
    at org.springframework.beans.factory.xml.BeanDefinitionParserDelegate.parseCustomElement(BeanDefinitionParserDelegate.java:1371)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.parseBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:179)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.doRegisterBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:149)
    at org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader.registerBeanDefinitions(DefaultBeanDefinitionDocumentReader.java:96)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.registerBeanDefinitions(XmlBeanDefinitionReader.java:511)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.doLoadBeanDefinitions(XmlBeanDefinitionReader.java:391)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:338)
    at org.springframework.beans.factory.xml.XmlBeanDefinitionReader.loadBeanDefinitions(XmlBeanDefinitionReader.java:310)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:188)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:224)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:195)
    at org.springframework.beans.factory.support.AbstractBeanDefinitionReader.loadBeanDefinitions(AbstractBeanDefinitionReader.java:257)
    at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:128)
    at org.springframework.context.support.AbstractXmlApplicationContext.loadBeanDefinitions(AbstractXmlApplicationContext.java:94)
    at org.springframework.context.support.AbstractRefreshableApplicationContext.refreshBeanFactory(AbstractRefreshableApplicationContext.java:130)
    at org.springframework.context.support.AbstractApplicationContext.obtainFreshBeanFactory(AbstractApplicationContext.java:638)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:523)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:144)
    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:85)
    at com.witacm.springframework.SpringFrameworkDemo0.main(SpringFrameworkDemo0.java:15)
Caused by: org.springframework.core.NestedIOException: ASM ClassReader failed to parse class file - probably due to a new Java class file version that isn't supported yet: file [D:\Javaweb\SpringFramework\out\production\SpringFramework\com\witacm\springframework\aop\StudentDAO.class]; nested exception is java.lang.IllegalArgumentException: Unsupported class file major version 61
    at org.springframework.core.type.classreading.SimpleMetadataReader.getClassReader(SimpleMetadataReader.java:60)
    at org.springframework.core.type.classreading.SimpleMetadataReader.<init>(SimpleMetadataReader.java:49)
    at org.springframework.core.type.classreading.SimpleMetadataReaderFactory.getMetadataReader(SimpleMetadataReaderFactory.java:103)
    at org.springframework.core.type.classreading.CachingMetadataReaderFactory.getMetadataReader(CachingMetadataReaderFactory.java:123)
    at org.springframework.context.annotation.ClassPathScanningCandidateComponentProvider.scanCandidateComponents(ClassPathScanningCandidateComponentProvider.java:429)
    ... 25 more
Caused by: java.lang.IllegalArgumentException: Unsupported class file major version 61
    at org.springframework.asm.ClassReader.<init>(ClassReader.java:196)
    at org.springframework.asm.ClassReader.<init>(ClassReader.java:177)
    at org.springframework.asm.ClassReader.<init>(ClassReader.java:163)
    at org.springframework.asm.ClassReader.<init>(ClassReader.java:284)
    at org.springframework.core.type.classreading.SimpleMetadataReader.getClassReader(SimpleMetadataReader.java:57)
    ... 29 more

原因是JDK版本过高。我从官网下的aspectj-1.9.7.jar，aspectjweaver-1.9.8.jar，应该是最新的依赖了。JDK版本是$17$是罪魁祸首。把JDK版本降为$11$就解决了。

补充说明

改这儿就可以了。