依赖于 spring 钩子

线程池销毁的例子 1.java

/**
     * 在一个 bean 被销毁以前对它应用本处理器
     * Apply this BeanPostProcessor to the given bean instance before its
     * destruction, e.g. invoking custom destruction callbacks.
     * <p>Like DisposableBean's {@code destroy} and a custom destroy method, this
     * callback will only apply to beans which the container fully manages the
     * lifecycle for. This is usually the case for singletons and scoped beans.
     *
     * @param bean     the bean instance to be destroyed
     * @param beanName the name of the bean
     * @throws BeansException in case of errors
     * @see DisposableBean#destroy()
     * @see AbstractBeanDefinition#setDestroyMethodName(String)
     */
    @Override
    public void postProcessBeforeDestruction(final Object bean, final String beanName) throws BeansException {
        // 先清理 bean 和 线程池的映射表的 entry
        ExecutorElement executorElement = this.beanToPool.remove(bean);
        // 如果依赖 requiresDestruction，这里不会返回 null，但为预防万一，还是做判空检查。
        if (null != executorElement) {
            // 获取全局引用数据
            AtomicInteger referenceCount = this.poolReference.get(executorElement);
            // 如果当前对线程池的应用已经为空或者引用数在本次清理中降为 0，则直接关闭线程池，且清理 poolReference。
            if (null == referenceCount || 0 == referenceCount.decrementAndGet()) {
                ExecutorServiceUtils.shutdownExecutor(executorElement.getExecutorService());
                poolReference.remove(executorElement);
            }
        }
    }

    /**
     * 确认一个 bean 被销毁之前要不要被这个处理器处理。
     * 默认都会被这个处理器处理。
     *
     * @param bean the bean instance to check
     * @return {@code true} if {@link #postProcessBeforeDestruction} is supposed to
     * be called for this bean instance eventually, or {@code false} if not needed
     * @since 4.3
     */
    @Override
    public boolean requiresDestruction(final Object bean) {
        return beanToPool.containsKey(bean);
    }