JavaMailSender 自动注入 显示错误！

Question

Error creating bean with name 'testController': Unsatisfied dependency expressed through field 'mailSender'; nested exception is org.springframework.beans.factory.

NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.mail.javamail.JavaMailSender' available: expected at least 1 bean which qualifies as autowire candidate. 

Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

一加上

@Autowired

JavaMailSender mailSender 

就会报错...