1.错误信息 

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'userController': Unsatisfied dependency expressed through field 'iUserService'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'IUserServiceImpl': Unsatisfied dependency expressed through field 'userMapper'; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'com.ywj.ssm.mapper.UserMapper' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

2.解决误区 

我刚碰到这个问题的时候根据错误信息我一直以为是我自己的注解或者是扫描路径有错误导致依赖关系没有成功找到所以导致的报错然后实际上并不是，所以我浪费了很多的时间

解决方法在web.xml种加上

 <!-- 读取Spring上下文的监听器 -->
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>

然后再贴出我修改后的web.xml文件供大家参考

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd"
         version="3.1">
  <display-name>Archetype Created Web Application</display-name>
  <!-- Spring和web项目集成start -->
  <!-- spring上下文配置文件 -->
  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>classpath:applicationContext.xml</param-value>
  </context-param>
  <!-- 读取Spring上下文的监听器 -->
  <listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
  </listener>
  <!-- Spring和web项目集成end -->

  <!-- 防止Spring内存溢出监听器 -->
  <listener>
    <listener-class>org.springframework.web.util.IntrospectorCleanupListener</listener-class>
  </listener>

  <!-- 中文乱码处理 -->
  <filter>
    <filter-name>encodingFilter</filter-name>
    <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
    <!--web.xml 3.0的新特性，是否支持异步-->
    <async-supported>true</async-supported>
    <init-param>
      <param-name>encoding</param-name>
      <param-value>UTF-8</param-value>
    </init-param>
  </filter>
  <filter-mapping>
    <filter-name>encodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>

  <!-- Spring MVC servlet -->
  <servlet>
    <servlet-name>SpringMVC</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <!--此参数可以不配置，默认值为：/WEB-INF/springmvc-servlet.xml-->
    <init-param>
      <param-name>contextConfigLocation</param-name>
      <param-value>classpath:spring-mvc.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
    <!--web.xml 3.0的新特性，是否支持异步-->
    <async-supported>true</async-supported>
  </servlet>
  <servlet-mapping>
    <servlet-name>SpringMVC</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
</web-app>