Error creating bean with name 'xxx' defined in URL [xxx]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [xxx]: Constructor threw exception; nested exception is java.lang.NullPointerException
問題是在idea里正常執行，但是打包後啟動就會報錯

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2020-10-10 10:48:27.769 ERROR 19548 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'stationManager' defined in URL [jar:file:/D:/project/xxx/target/xxx.jar!/BOOT-INF/classes!/com/xxx/work/StationManager.class]: Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.xxx.work.StationManager]: Constructor threw exception; nested exception is java.lang.NullPointerException
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1229)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1128)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:535)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:495)
        at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:317)
        at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
        at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:315)
        at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
        at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:759)
        at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:869)
        at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550)
        at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:140)
        at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:762)
        at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:398)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:330)
        at com.xxx.AppApplication.main(AppApplication.java:25)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48)
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:87)
        at org.springframework.boot.loader.Launcher.launch(Launcher.java:50)
        at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51)
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.xxx.work.StationManager]: Constructor threw exception; nested exception is java.lang.NullPointerException
        at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:182)
        at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:87)
        at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1221)
        ... 23 common frames omitted
Caused by: java.lang.NullPointerException: null
        at com.xxx.Configuration.ApplicationContextProvider.getBean(ApplicationContextProvider.java:53)
        at com.xxx.work.StationManager.<init>(StationManager.java:28)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
        at java.lang.reflect.Constructor.newInstance(Unknown Source)
        at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:170)
        ... 25 common frames omitted
 

解決：刪掉報錯的stationManager（因為是上一個專案複製過來的沒用到的檔案）就可以正常執行jar包了，我也不知道為什麼！