关于spring:底层到底做了什么-从spring-的Async-看AOP调用过程

上文曾经讲过 @EnableAsync 的 bean 构建过程，这里持续合成 @Async 执行过程，以及 spring 的 AOP 调用过程。

先上 demo

public class ApiGatewayApplication {public static void main(String[] args) {SpringApplication.run(ApiGatewayApplication.class, args);

    AsyncTest test = BeanUtils.getBean("asyncTest");
    test.test();//1}
}

@Configuration
public class WorkPool {@Bean("WorkPool")
    public ThreadPoolTaskExecutor  taskExecutor(){ThreadPoolTaskExecutor threadPoolTaskExecutor = new ThreadPoolTaskExecutor();
        threadPoolTaskExecutor.initialize();
        return threadPoolTaskExecutor;
    }
}

@Component
public class AsyncTest {

    @Async
    public void test() {System.out.printf("test"); 
    }

}

1、这一步是上面的重点，底层是怎么调用。

    private static class DynamicAdvisedInterceptor implements MethodInterceptor, Serializable {

        @Nullable
        public Object intercept(Object proxy, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
                Object retVal;
                if (chain.isEmpty() && Modifier.isPublic(method.getModifiers())) {Object[] argsToUse = AopProxyUtils.adaptArgumentsIfNecessary(method, args);
                    retVal = methodProxy.invoke(target, argsToUse);//2
                } else {retVal = (new CglibAopProxy.CglibMethodInvocation(proxy, target, method, args, targetClass, chain, methodProxy)).proceed();//3} 
}

2、如果没有 AOP 行为，间接调用原 bean。
3、如果有 AOP 行为，结构一个 Cglib 的 CglibMethodInvocation 办法回调对象。

public class ReflectiveMethodInvocation implements ProxyMethodInvocation, Cloneable {public Object proceed() throws Throwable {Object interceptorOrInterceptionAdvice = this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);
            if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher) {InterceptorAndDynamicMethodMatcher dm = (InterceptorAndDynamicMethodMatcher)interceptorOrInterceptionAdvice;
                Class<?> targetClass = this.targetClass != null ? this.targetClass : this.method.getDeclaringClass();
                return dm.methodMatcher.matches(this.method, targetClass, this.arguments) ? dm.interceptor.invoke(this) : this.proceed();} else {return ((MethodInterceptor)interceptorOrInterceptionAdvice).invoke(this);//4
            }
        }
    }

4、找到 AsyncExecutionInterceptor 执行器

public class AsyncExecutionInterceptor extends AsyncExecutionAspectSupport implements MethodInterceptor, Ordered {
 @Nullable
    public Object invoke(MethodInvocation invocation) throws Throwable {return this.doSubmit(task, executor, invocation.getMethod().getReturnType());//4
 }

 public class ThreadPoolTaskExecutor extends ExecutorConfigurationSupport implements AsyncListenableTaskExecutor, SchedulingTaskExecutor {public <T> Future<T> submit(Callable<T> task) { //5
        ThreadPoolExecutor executor = this.getThreadPoolExecutor();

        try {return executor.submit(task);
        } catch (RejectedExecutionException var4) {throw new TaskRejectedException("Executor [" + executor + "] did not accept task:" + task, var4);
        }
    }
 }

4、通过 doSubmit 将工作发给 TaskExecutor，实现 Async 异步的性能。
5、ThreadPoolTaskExecutor 就是在 demo 中定义的 WorkPool。

最终实现 Asyn 异步调用。