springmvc处理图片上传时使用MultipartFile 接收为null。

Question

1.使用富文本编辑器上传图片，在controller中使用MultipartFile接收为null。debug发现，request经过dispatcherServlet是有值的。而且可以正常映射到方法中去。
2.springmvc中的配置：

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
    <!-- 设定默认编码 -->
    <property name="defaultEncoding" value="UTF-8"></property>
    <!-- 设定文件上传的最大值5MB，5*1024*1024 -->
    <property name="maxUploadSize" value="5242880"></property>
</bean>

3.DEBUG信息：
DEBUG [http-bio-90-exec-10] - DispatcherServlet with name 'web' processing GET request for [/js/kindeditor-4.1.10/lang/zh_CN.js]
DEBUG [http-bio-90-exec-10] - Looking up handler method for path /js/kindeditor-4.1.10/lang/zh_CN.js
DEBUG [http-bio-90-exec-10] - Did not find handler method for [/js/kindeditor-4.1.10/lang/zh_CN.js]
DEBUG [http-bio-90-exec-10] - Matching patterns for request [/js/kindeditor-4.1.10/lang/zh_CN.js] are [/js/**]
DEBUG [http-bio-90-exec-10] - URI Template variables for request [/js/kindeditor-4.1.10/lang/zh_CN.js] are {}
DEBUG [http-bio-90-exec-10] - Mapping [/js/kindeditor-4.1.10/lang/zh_CN.js] to HandlerExecutionChain with handler [ResourceHttpRequestHandler [locations=[ServletContext resource [/js/]], resolvers=[org.springframework.web.servlet.resource.PathResourceResolver@105fda6b]]] and 1 interceptor
DEBUG [http-bio-90-exec-10] - Last-Modified value for [/js/kindeditor-4.1.10/lang/zh_CN.js] is: -1
DEBUG [http-bio-90-exec-10] - Null ModelAndView returned to DispatcherServlet with name 'web': assuming HandlerAdapter completed request handling
DEBUG [http-bio-90-exec-10] - Successfully completed request
DEBUG [http-bio-90-exec-10] - DispatcherServlet with name 'web' processing GET request for [/js/kindeditor-4.1.10/plugins/multiimage/images/swfupload.swf]
DEBUG [http-bio-90-exec-10] - Looking up handler method for path /js/kindeditor-4.1.10/plugins/multiimage/images/swfupload.swf
DEBUG [http-bio-90-exec-10] - Did not find handler method for [/js/kindeditor-4.1.10/plugins/multiimage/images/swfupload.swf]
DEBUG [http-bio-90-exec-10] - Matching patterns for request [/js/kindeditor-4.1.10/plugins/multiimage/images/swfupload.swf] are [/js/**]
DEBUG [http-bio-90-exec-10] - URI Template variables for request [/js/kindeditor-4.1.10/plugins/multiimage/images/swfupload.swf] are {}
DEBUG [http-bio-90-exec-10] - Mapping [/js/kindeditor-4.1.10/plugins/multiimage/images/swfupload.swf] to HandlerExecutionChain with handler [ResourceHttpRequestHandler [locations=[ServletContext resource [/js/]], resolvers=[org.springframework.web.servlet.resource.PathResourceResolver@105fda6b]]] and 1 interceptor
DEBUG [http-bio-90-exec-10] - Last-Modified value for [/js/kindeditor-4.1.10/plugins/multiimage/images/swfupload.swf] is: -1
DEBUG [http-bio-90-exec-10] - Null ModelAndView returned to DispatcherServlet with name 'web': assuming HandlerAdapter completed request handling
DEBUG [http-bio-90-exec-10] - Successfully completed request
DEBUG [http-bio-90-exec-10] - DispatcherServlet with name 'web' processing POST request for [/pic/upload]
DEBUG [http-bio-90-exec-10] - Found multipart file [uploadFile] of size 345594 bytes with original filename [natalie.png], stored at [D:ideaWorkspace2e3mallwebtargettomcatworkTomcatlocalhost_upload_605390ea_b9db_44ee_9bf4_b426b27db686_00000001.tmp]
DEBUG [http-bio-90-exec-10] - Looking up handler method for path /pic/upload
DEBUG [http-bio-90-exec-10] - Returning handler method [public java.util.Map cn.e3mall.controller.PictureController.fileUpload(org.springframework.web.multipart.MultipartFile)]
DEBUG [http-bio-90-exec-10] - Returning cached instance of singleton bean 'pictureController'
DEBUG [http-bio-90-exec-10] - Skip CORS processing, request is a same-origin one

Answer 1

发完一分钟就意识到了这犯的是低级错误，在controller的方法形参类型虽然为MultipartFile，但参数名必须为uploadFile，否则无法映射成功，自然接收不到request域中的对象，果然不要出了什么事情立马去网上找答案。很多做法完全是背道而驰。
谨以此为戒。

Answer 2

我们学的时候说可以改变参数名啊 现在都是attach 实现信息新增的时候可以上传成功 但是在修改信息的时候 将原来的旧图片删除 重新新增一个图片的时候就获取不到值了 是怎么回事 求大神指教