最近在做spring boot 来实现发送邮件的功能，通过网上查到的方法，在build.gradle添加了
compile('org.springframework.boot:spring-boot-starter-mail')
在application.properties中添加spring.mail.host时，启动spring boot
就报了下面的错误
困扰3天了 哪位大神明白指点一下

2018-12-07 09:11:06.921  INFO 2636 --- [           main] ationConfigEmbeddedWebApplicationContext : Closing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@158b9e9: startup date [Fri Dec 07 09:11:05 CST 2018]; root of context hierarchy

2018-12-07 09:11:06.921  WARN 2636 --- [           main] ationConfigEmbeddedWebApplicationContext : Exception thrown from LifecycleProcessor on context close



java.lang.IllegalStateException: LifecycleProcessor not initialized - call 'refresh' before invoking lifecycle methods via the context: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@158b9e9: startup date [Fri Dec 07 09:11:05 CST 2018]; root of context hierarchy

	at org.springframework.context.support.AbstractApplicationContext.getLifecycleProcessor(AbstractApplicationContext.java:427) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:999) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.context.support.AbstractApplicationContext.close(AbstractApplicationContext.java:958) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.boot.SpringApplication.handleRunFailure(SpringApplication.java:750) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]

	at org.springframework.boot.SpringApplication.run(SpringApplication.java:314) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]

	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]

	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]

	at com.downloadweb.KkFrameworkApplication.main(KkFrameworkApplication.java:26) [bin/:na]



2018-12-07 09:11:06.953 ERROR 2636 --- [           main] o.s.b.f.s.DefaultListableBeanFactory     : Destroy method on bean with name 'org.springframework.boot.autoconfigure.internalCachingMetadataReaderFactory' threw an exception



java.lang.IllegalStateException: ApplicationEventMulticaster not initialized - call 'refresh' before multicasting events via the context: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@158b9e9: startup date [Fri Dec 07 09:11:05 CST 2018]; root of context hierarchy

	at org.springframework.context.support.AbstractApplicationContext.getApplicationEventMulticaster(AbstractApplicationContext.java:414) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.context.support.ApplicationListenerDetector.postProcessBeforeDestruction(ApplicationListenerDetector.java:97) ~[spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.beans.factory.support.DisposableBeanAdapter.destroy(DisposableBeanAdapter.java:253) ~[spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.destroyBean(DefaultSingletonBeanRegistry.java:578) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.destroySingleton(DefaultSingletonBeanRegistry.java:554) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.beans.factory.support.DefaultListableBeanFactory.destroySingleton(DefaultListableBeanFactory.java:961) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.destroySingletons(DefaultSingletonBeanRegistry.java:523) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.beans.factory.support.FactoryBeanRegistrySupport.destroySingletons(FactoryBeanRegistrySupport.java:230) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.beans.factory.support.DefaultListableBeanFactory.destroySingletons(DefaultListableBeanFactory.java:968) [spring-beans-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.context.support.AbstractApplicationContext.destroyBeans(AbstractApplicationContext.java:1030) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.context.support.AbstractApplicationContext.doClose(AbstractApplicationContext.java:1006) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.context.support.AbstractApplicationContext.close(AbstractApplicationContext.java:958) [spring-context-4.3.10.RELEASE.jar:4.3.10.RELEASE]

	at org.springframework.boot.SpringApplication.handleRunFailure(SpringApplication.java:750) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]

	at org.springframework.boot.SpringApplication.run(SpringApplication.java:314) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]

	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]

	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.6.RELEASE.jar:1.5.6.RELEASE]

	at com.downloadweb.KkFrameworkApplication.main(KkFrameworkApplication.java:26) [bin/:na]



Exception in thread "main" java.lang.NoClassDefFoundError: org/springframework/mail/javamail/JavaMailSenderImpl

	at java.lang.Class.getDeclaredMethods0(Native Method)

	at java.lang.Class.privateGetDeclaredMethods(Unknown Source)

	at java.lang.Class.getDeclaredMethods(Unknown Source)

	at org.springframework.util.ReflectionUtils.getDeclaredMethods(ReflectionUtils.java:613)

	at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:524)

	at org.springframework.util.ReflectionUtils.doWithMethods(ReflectionUtils.java:510)

	at org.springframework.util.ReflectionUtils.getUniqueDeclaredMethods(ReflectionUtils.java:570)

	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.getTypeForFactoryMethod(AbstractAutowireCapableBeanFactory.java:697)

	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.determineTar