在Spring项目时报错：
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'demoController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.springdemo.service.DemoDeviceService com.springdemo.controller.DemoController.demoDeviceService; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [com.springdemo.service.DemoDeviceService] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
web.xml中配置了：
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
classpath:spring.xml,
classpath:spring-hibernate.xml
</param-value>
</context-param>
Tomcat启动日志: No Spring WebApplicationInitializer types detected on classpath
但是没有配置：
<listener>
<listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>
配置后后正常
Tomcat启动日志: Initializing Spring root WebApplicationContext
Spring提供ServletContentListener的一个实现类ContextLoaderListener监听器，该类可以作为Listener使用，在启动Tomcat容器的时候，该类的作用就是自动装载ApplicationContext的配置信息，如果没有设置contextConfigLocation的初始参数则会使用默认参数WEB-INF路径下的application.xml文件。如果需要自定义读取多个配置文件或者修改默认路径，则可以在web.xml中设置：
<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
classpath:spring.xml,
classpath:spring-hibernate.xml
</param-value>
</context-param>
ContextLoaderListener会读取这些XML文件并产生 WebApplicationContext对象，然后将这个对象放置在ServletContext的属性
里，这样我们只要可以得到Servlet就可 以得到WebApplicationContext对象，并利用这个对象访问spring 容器管理的bean。
初始成功之后显示如下
信息: Initializing Spring root WebApplicationContext