/**
 * 用于spring session，防止每次創(chuàng)建一個線程
 * @return
 */
@Bean
public ThreadPoolTaskExecutor springSessionRedisTaskExecutor(){
  ThreadPoolTaskExecutor springSessionRedisTaskExecutor = new ThreadPoolTaskExecutor();
  springSessionRedisTaskExecutor.setCorePoolSize(8);
  springSessionRedisTaskExecutor.setMaxPoolSize(16);
  springSessionRedisTaskExecutor.setKeepAliveSeconds(10);
  springSessionRedisTaskExecutor.setQueueCapacity(1000);
  springSessionRedisTaskExecutor.setThreadNamePrefix("Spring session redis executor thread: ");
  return springSessionRedisTaskExecutor;
}

@Autowired(
  required = false  //該處理監(jiān)聽的線程池不是必須的，如果不自定義默認(rèn)將使用SimpleAsyncTaskExecutor線程池
)
@Qualifier("springSessionRedisTaskExecutor")
public void setRedisTaskExecutor(Executor redisTaskExecutor) {
  this.redisTaskExecutor = redisTaskExecutor;
}

@Bean
public RedisMessageListenerContainer redisMessageListenerContainer() {
  RedisMessageListenerContainer container = new RedisMessageListenerContainer();
  container.setConnectionFactory(this.redisConnectionFactory);
  if (this.redisTaskExecutor != null) {
    container.setTaskExecutor(this.redisTaskExecutor);
  }
  if (this.redisSubscriptionExecutor != null) {
    container.setSubscriptionExecutor(this.redisSubscriptionExecutor);
  }
  container.addMessageListener(this.sessionRepository(), Arrays.asList(new PatternTopic("__keyevent@*:del"), new PatternTopic("__keyevent@*:expired")));
  container.addMessageListener(this.sessionRepository(), Collections.singletonList(new PatternTopic(this.sessionRepository().getSessionCreatedChannelPrefix() + "*")));
  return container;
}
RedisMessageListenerContainer正是處理監(jiān)聽的類，RedisMessageListenerContainer設(shè)置了不為空的redisTaskExecutor，因為spring session默認(rèn)沒有配置該Executor，那RedisMessageListenerContainer在處理監(jiān)聽時怎么使用線程呢？我們接著看RedisMessageListenerContainer的源碼：
public void afterPropertiesSet() {
  if (this.taskExecutor == null) {
    this.manageExecutor = true;
    this.taskExecutor = this.createDefaultTaskExecutor();
  }
  if (this.subscriptionExecutor == null) {
    this.subscriptionExecutor = this.taskExecutor;
  }
  this.initialized = true;
}
protected TaskExecutor createDefaultTaskExecutor() {
  String threadNamePrefix = this.beanName != null ? this.beanName + "-" : DEFAULT_THREAD_NAME_PREFIX;
  return new SimpleAsyncTaskExecutor(threadNamePrefix);
}