之前偶然看到一篇文章 利用aop实现热拔插（类似于插件） ，里面的实现挺好玩。今天我们也来玩一把
org.aopalliance.aop.Advice
“通知”，表示 Aspect 在特定的 Join point 采取的操作。包括 “around”, “before” and “after 等 Advice，大体上分为了三类：BeforeAdvice、MethodInterceptor、AfterAdvice
org.springframework.aop.Advisor
“通知者”，它持有 Advice，是 Spring AOP 的一个基础接口。 它的子接口 PointcutAdvisor 是一个功能完善接口，它涵盖了绝大部分的 Advisor。
org.springframework.aop.framework.Advised
AOP 代理工厂配置类接口。提供了操作和管理 Advice 和 Advisor 的能力。它的实现类 ProxyFactory 是 Spring AOP 主要用于创建 AOP 代理类的核心类。
1、动态管理advice端点实现
@RestControllerEndpoint(id = "proxy")
@RequiredArgsConstructor
public class ProxyMetaDefinitionControllerEndPoint {
private final ProxyMetaDefinitionRepository proxyMetaDefinitionRepository;
@GetMapping("listMeta")
public List<ProxyMetaDefinition> getProxyMetaDefinitions(){
return proxyMetaDefinitionRepository.getProxyMetaDefinitions();
}
@GetMapping("{id}")
public ProxyMetaDefinition getProxyMetaDefinition(@PathVariable("id") String proxyMetaDefinitionId){
return proxyMetaDefinitionRepository.getProxyMetaDefinition(proxyMetaDefinitionId);
}
@PostMapping("save")
public String save(@RequestBody ProxyMetaDefinition definition){
try {
proxyMetaDefinitionRepository.save(definition);
return "success";
} catch (Exception e) {
}
return "fail";
}
@PostMapping("delete/{id}")
public String delete(@PathVariable("id")String proxyMetaDefinitionId){
try {
proxyMetaDefinitionRepository.delete(proxyMetaDefinitionId);
return "success";
} catch (Exception e) {
}
return "fail";
}
}
2、利用事件监听机制捕获安装或者卸载插件
@RequiredArgsConstructor
public class ProxyMetaDefinitionChangeListener {
private final AopPluginFactory aopPluginFactory;
@EventListener
public void listener(ProxyMetaDefinitionChangeEvent proxyMetaDefinitionChangeEvent){
ProxyMetaInfo proxyMetaInfo = aopPluginFactory.getProxyMetaInfo(proxyMetaDefinitionChangeEvent.getProxyMetaDefinition());
switch (proxyMetaDefinitionChangeEvent.getOperateEventEnum()){
case ADD:
aopPluginFactory.installPlugin(proxyMetaInfo);
break;
case DEL:
aopPluginFactory.uninstallPlugin(proxyMetaInfo.getId());
break;
}
}
}
3、安装插件
public void installPlugin(ProxyMetaInfo proxyMetaInfo){
if(StringUtils.isEmpty(proxyMetaInfo.getId())){
proxyMetaInfo.setId(proxyMetaInfo.getProxyUrl() + SPIILT + proxyMetaInfo.getProxyClassName());
}
AopUtil.registerProxy(defaultListableBeanFactory,proxyMetaInfo);
}
4、安装插件核心实现
public static void registerProxy(DefaultListableBeanFactory beanFactory,ProxyMetaInfo proxyMetaInfo){
AspectJExpressionPointcutAdvisor advisor = getAspectJExpressionPointcutAdvisor(beanFactory, proxyMetaInfo);
addOrDelAdvice(beanFactory,OperateEventEnum.ADD,advisor);
}
private static AspectJExpressionPointcutAdvisor getAspectJExpressionPointcutAdvisor(DefaultListableBeanFactory beanFactory, ProxyMetaInfo proxyMetaInfo) {
BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition();
GenericBeanDefinition beanDefinition = (GenericBeanDefinition) builder.getBeanDefinition();
beanDefinition.setBeanClass(AspectJExpressionPointcutAdvisor.class);
AspectJExpressionPointcutAdvisor advisor = new AspectJExpressionPointcutAdvisor();
advisor.setExpression(proxyMetaInfo.getPointcut());
advisor.setAdvice(Objects.requireNonNull(getMethodInterceptor(proxyMetaInfo.getProxyUrl(), proxyMetaInfo.getProxyClassName())));
beanDefinition.setInstanceSupplier((Supplier<AspectJExpressionPointcutAdvisor>) () -> advisor);
beanFactory.registerBeanDefinition(PROXY_PLUGIN_PREFIX + proxyMetaInfo.getId(),beanDefinition);
return advisor;
}
5、卸载插件
public void uninstallPlugin(String id){
String beanName = PROXY_PLUGIN_PREFIX + id;
if(defaultListableBeanFactory.containsBean(beanName)){
AopUtil.destoryProxy(defaultListableBeanFactory,id);
}else{
throw new NoSuchElementException("Plugin not found: " + id);
}
}
6、卸载插件核心实现
public static void destoryProxy(DefaultListableBeanFactory beanFactory,String id){
String beanName = PROXY_PLUGIN_PREFIX + id;
if(beanFactory.containsBean(beanName)){
AspectJExpressionPointcutAdvisor advisor = beanFactory.getBean(beanName,AspectJExpressionPointcutAdvisor.class);
addOrDelAdvice(beanFactory,OperateEventEnum.DEL,advisor);
beanFactory.destroyBean(beanFactory.getBean(beanName));
}
}
7、操作advice实现
public static void addOrDelAdvice(DefaultListableBeanFactory beanFactory, OperateEventEnum operateEventEnum,AspectJExpressionPointcutAdvisor advisor){
AspectJExpressionPointcut pointcut = (AspectJExpressionPointcut) advisor.getPointcut();
for (String beanDefinitionName : beanFactory.getBeanDefinitionNames()) {
Object bean = beanFactory.getBean(beanDefinitionName);
if(!(bean instanceof Advised)){
if(operateEventEnum == OperateEventEnum.ADD){
buildCandidateAdvised(beanFactory,advisor,bean,beanDefinitionName);
}
continue;
}
Advised advisedBean = (Advised) bean;
boolean isFindMatchAdvised = findMatchAdvised(advisedBean.getClass(),pointcut);
if(operateEventEnum == OperateEventEnum.DEL){
if(isFindMatchAdvised){
advisedBean.removeAdvice(advisor.getAdvice());
log.info("########################################## Remove Advice -->【{}】 For Bean -->【{}】 SUCCESS !",advisor.getAdvice().getClass().getName(),bean.getClass().getName());
}
}else if(operateEventEnum == OperateEventEnum.ADD){
if(isFindMatchAdvised){
advisedBean.addAdvice(advisor.getAdvice());
log.info("########################################## Add Advice -->【{}】 For Bean -->【{}】 SUCCESS !",advisor.getAdvice().getClass().getName(),bean.getClass().getName());
}
}
}
}
1、创建一个service
@Service
@Slf4j
public class HelloService implements BeanNameAware, BeanFactoryAware {
private BeanFactory beanFactory;
private String beanName;
@SneakyThrows
public String sayHello(String message) {
Object bean = beanFactory.getBean(beanName);
log.info("============================ {} is Advised : {}",bean, bean instanceof Advised);
TimeUnit.SECONDS.sleep(new Random().nextInt(3));
log.info("============================ hello:{}",message);
return "hello:" + message;
}
@Override
public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
this.beanFactory = beanFactory;
}
@Override
public void setBeanName(String name) {
this.beanName = name;
}
}
2、创建一个controller
@RestController
@RequestMapping("hello")
@RequiredArgsConstructor
public class HelloController {
private final HelloService helloService;
@GetMapping("{message}")
public String sayHello(@PathVariable("message")String message){
return helloService.sayHello(message);
}
}
3、准备一个日志切面jar
切面内容为
@Slf4j
public class LogMethodInterceptor implements MethodInterceptor {
@Override
public Object invoke(MethodInvocation invocation) throws Throwable {
Object result;
try {
result = invocation.proceed();
} finally {
log.info(">>>>>>>>>>>>>>>>>>>>>>>>TargetClass:【{}】,method:【{}】,args:【{}】",invocation.getThis().getClass().getName(),invocation.getMethod().getName(), Arrays.toString(invocation.getArguments()));
}
return result;
}
}
4、测试
场景一：未添加切面时
浏览器访问：http://localhost:8080/hello/zhangsan
观察控制台
场景二：通过postman动态操作代理
1、新增代理
观察控制台
: ########################################## BuildCandidateAdvised -->【com.github.lybgeek.aop.test.hello.service.HelloService】 With Advice -->【com.github.lybgeek.interceptor.LogMethodInterceptor】 SUCCESS !
此时浏览器访问：http://localhost:8080/hello/zhangsan
再次观察控制台
出现了切面日志信息，说明代理生效
2、删除代理
观察控制台
########################################## Remove Advice -->【com.github.lybgeek.interceptor.LogMethodInterceptor】 For Bean -->【com.github.lybgeek.aop.test.hello.service.HelloService$$EnhancerBySpringCGLIB$$7bc75aa3】 SUCCESS !
此时浏览器访问：http://localhost:8080/hello/zhangsan
再次观察控制台
此时没有出现切面日志信息，说明代理删除成功
本文实现热插拔AOP就在于对advice、advised、advisor、pointcut概念的理解，这是实现热插拔AOP的前提，其次就是对自定义classloader也需要有一定的了解，因为我们jar不一定从classpath底下加载，也有可能来源其他地方，比如远程链接啥的，最后就是把原先spring自动帮我们实现aop，我们利用相关的api，自己手动实现一遍，示例代码的api只是利用spring api其中一种实现方式，它还有多种实现方式，比如可以利用TargetSource，感兴趣的朋友，也可以自己实现一把。
至于那个代理增删改查端点contoller，是我之前看springcloud gateway的路由定位器端点源码，一直没找到机会实现一下，就把他搬来这个示例实现一把，加深一下印象
https://github.com/lyb-geek/springboot-learning/tree/master/springboot-dynamic-aop