springmvc上传附件出现异常Expected MultipartHttpServletRequest: is a MultipartResolver configured?

异常及解决方案：
java.lang.IllegalArgumentException: Expected MultipartHttpServletRequest: is a MultipartResolver configured?
    at org.springframework.util.Assert.notNull(Assert.java:112)
    at org.springframework.web.method.annotation.RequestParamMethodArgumentResolver.resolveName(RequestParamMethodArgumentResolver.java:151)
    at org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver.resolveArgument(AbstractNamedValueMethodArgumentResolver.java:86)
    ...
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
    at java.lang.Thread.run(Thread.java:662)

解决方法：

spring mvc中上传附件，需要做两步操作

1. 引入包commons-fileupload-1.3.jar，版本号可以根据项目情况调整；
2. 在spring mvc配置文件中增加配置，文件大小限制可根据项目情况调整：

   <!-- 上传文件拦截，设置最大上传文件大小   10M=10*1024*1024(B)=10485760 bytes -->  
   <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">  
       <property name="maxUploadSize" value="10485760" />  
   </bean>

3. 此处我的错误是将bean中的id写成了

   commonsMultipartResolver

4. id="multipartResolver"，这个不能省略，而且名字不能改，否则spring容器找不到。