spring异步任务相关

    自定义异步任务执行的Executor，默认用的是SimpleAsyncTaskExecutor

 

// AsyncExecutionInterceptor
@Override
public Object invoke(final MethodInvocation invocation) throws Throwable {
		Class<?> targetClass = (invocation.getThis() != null ? AopUtils.getTargetClass(invocation.getThis()) : null);
		Method specificMethod = ClassUtils.getMostSpecificMethod(invocation.getMethod(), targetClass);
		final Method userDeclaredMethod = BridgeMethodResolver.findBridgedMethod(specificMethod);

		AsyncTaskExecutor executor = determineAsyncExecutor(userDeclaredMethod);// a
		if (executor == null) {
			throw new IllegalStateException(
					"No executor specified and no default executor set on AsyncExecutionInterceptor either");
		}

		Callable<Object> task = new Callable<Object>() {
			@Override
			public Object call() throws Exception {
				try {
					Object result = invocation.proceed();
					if (result instanceof Future) {
						return ((Future<?>) result).get();
					}
				}
				catch (ExecutionException ex) {
					handleError(ex.getCause(), userDeclaredMethod, invocation.getArguments());
				}
				catch (Throwable ex) {
					handleError(ex, userDeclaredMethod, invocation.getArguments());
				}
				return null;
			}
		};

		return doSubmit(task, executor, invocation.getMethod().getReturnType());
	}

   a.AsyncTaskExecutor executor = determineAsyncExecutor(userDeclaredMethod);// a

// AsyncExecutionAspectSupport
protected AsyncTaskExecutor determineAsyncExecutor(Method method) {
		AsyncTaskExecutor executor = this.executors.get(method);
		if (executor == null) {
			Executor targetExecutor;
			String qualifier = getExecutorQualifier(method);
			if (StringUtils.hasLength(qualifier)) {
				targetExecutor = findQualifiedExecutor(this.beanFactory, qualifier);
			}
			else {
				targetExecutor = this.defaultExecutor;
				if (targetExecutor == null) {
					synchronized (this.executors) {
						if (this.defaultExecutor == null) {
							this.defaultExecutor = getDefaultExecutor(this.beanFactory);// b
						}
						targetExecutor = this.defaultExecutor;
					}
				}
			}
			if (targetExecutor == null) {
				return null;
			}
			executor = (targetExecutor instanceof AsyncListenableTaskExecutor ?
					(AsyncListenableTaskExecutor) targetExecutor : new TaskExecutorAdapter(targetExecutor));
			this.executors.put(method, executor);
		}
		return executor;
	}

 b.this.defaultExecutor = getDefaultExecutor(this.beanFactory);// b

// AsyncExecutionInterceptor
@Override
protected Executor getDefaultExecutor(BeanFactory beanFactory) {
		Executor defaultExecutor = super.getDefaultExecutor(beanFactory);// c
		return (defaultExecutor != null ? defaultExecutor : new SimpleAsyncTaskExecutor());
	}

 c.Executor defaultExecutor = super.getDefaultExecutor(beanFactory);// c

// AsyncExecutionAspectSupport
protected Executor getDefaultExecutor(BeanFactory beanFactory) {
		if (beanFactory != null) {
			try {
				// Search for TaskExecutor bean... not plain Executor since that would
				// match with ScheduledExecutorService as well, which is unusable for
				// our purposes here. TaskExecutor is more clearly designed for it.
				return beanFactory.getBean(TaskExecutor.class);
			}
			catch (NoUniqueBeanDefinitionException ex) {
				logger.debug("Could not find unique TaskExecutor bean", ex);
				try {
					return beanFactory.getBean(DEFAULT_TASK_EXECUTOR_BEAN_NAME, Executor.class);// 
				}
				catch (NoSuchBeanDefinitionException ex2) {
					if (logger.isInfoEnabled()) {
						logger.info("More than one TaskExecutor bean found within the context, and none is named " +
								"'taskExecutor'. Mark one of them as primary or name it 'taskExecutor' (possibly " +
								"as an alias) in order to use it for async processing: " + ex.getBeanNamesFound());
					}
				}
			}
			catch (NoSuchBeanDefinitionException ex) {
				logger.debug("Could not find default TaskExecutor bean", ex);
				try {
					return beanFactory.getBean(DEFAULT_TASK_EXECUTOR_BEAN_NAME, Executor.class);
				}
				catch (NoSuchBeanDefinitionException ex2) {
					logger.info("No task executor bean found for async processing: " +
							"no bean of type TaskExecutor and no bean named 'taskExecutor' either");
				}
				// Giving up -> either using local default executor or none at all...
			}
		}
		return null;
	}