SpringBoot+WebSocket+定时任务报错：Bean named ‘defaultSockJsTaskScheduler‘ is expected to be of type···

一、项目背景

根据项目需求要使用定时任务+WebSocket不断的往前台推送数据。当项目同时集成WebSocket+定时任务时会报错：Bean named 'defaultSockJsTaskScheduler' is expected to be of type···，报错信息如下

org.springframework.beans.factory.BeanNotOfRequiredTypeException: Bean named 'defaultSockJsTaskScheduler' is expected to be of type 'org.springframework.scheduling.TaskScheduler' but was actually of type 'org.springframework.beans.factory.support.NullBean'
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:395) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:227) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveNamedBean(DefaultListableBeanFactory.java:1172) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveNamedBean(DefaultListableBeanFactory.java:1139) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.resolveSchedulerBean(ScheduledAnnotationBeanPostProcessor.java:315) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.finishRegistration(ScheduledAnnotationBeanPostProcessor.java:256) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:233) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.scheduling.annotation.ScheduledAnnotationBeanPostProcessor.onApplicationEvent(ScheduledAnnotationBeanPostProcessor.java:105) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:172) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:165) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:404) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:361) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.finishRefresh(AbstractApplicationContext.java:898) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:554) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758) [spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) [spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) [spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
	at com.niutrans.localdeploymentserver.LocalDeploymentServerApplication.main(LocalDeploymentServerApplication.java:19) [classes/:na]

二、处理过程回顾

定时任务选择的是Spring自带的定时任务，先在项目中集成了WebSocket，编译，运行，测试后，功能好用。但是再加上定时任务后就报错了。

启动类代码如下：

@SpringBootApplication
@EnableWebSocket
@EnableScheduling
public class TestApplication {

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

}

三、解决方案

手动添加一个定时任务的配置类来创建一个ThreadPoolTaskScheduler对象。

@Configuration
public class ScheduledConfig {
 
	@Bean
	public TaskScheduler taskScheduler() {
		ThreadPoolTaskScheduler scheduling = new ThreadPoolTaskScheduler();
		scheduling.setPoolSize(10);
		scheduling.initialize();
		return scheduling;
	}
}

四、为什么

大致猜测，仅供参考！！！

报错大致意思是：名为'defaultSockJsTaskScheduler'的Bean应为'org.springframework.scheduling.TaskScheduler“但实际上是类型”org.springframework.beans.factory.support.NullBean'。这个异常是由(AbstractBeanFactory.java:395)抛出的。

启动时还会出现警告

2021-01-15 13:28:37.245  WARN 140 --- [           main] o.a.c.loader.WebappClassLoaderBase       : The web application [ROOT] appears to have started a thread named [ForkJoinPool.commonPool-worker-3] but has failed to stop it. This is very likely to create a memory leak. Stack trace of thread:
 sun.misc.Unsafe.park(Native Method)
 java.util.concurrent.ForkJoinPool.awaitWork(ForkJoinPool.java:1824)
 java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1693)
 java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:157)

警告大致意思是：web应用程序[ROOT]似乎启动了一个名为[ForkJoinPool.commonPool-worker-3]但是不能停止这个线程。这很可能会造成内存泄漏。

websocket需要创建线程，定时任务也需要创建线程，应该是websocket和定时任务在创建线程的时候发生了冲突，定时任务创建线程没有成功。

这个时候我们手动创建一个定时任务的线程池，使得定时任务使用自己的线线程池，就能解决冲突。

原文链接：https://blog.csdn.net/weixin_40877388/article/details/108278010