使用spring MVC框架进行文件上传，步骤如下：

1：配置web.xml文件。定义DispatcherServlet，DispatcherServlet处理的请求（.htm）也在同一个web.xml文件里使用url-mapping定义映射。

 <servlet>
  <servlet-name>upload</servlet-name>
  <servlet-class>org.springframework.web.servlet.DispatcherServlet
  </servlet-class>
  <load-on-startup>1</load-on-startup>
 </servlet>
 
 <servlet-mapping>
  <servlet-name>upload</servlet-name>
  <url-pattern>*.htm</url-pattern>
 </servlet-mapping>
2：定义upload-servlet.xml文件。
<bean id="multipartResolver"
       class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!-- set the max upload size100MB -->
        <property name="maxUploadSize">
        <value>104857600</value>
    </property>
    <property name="maxInMemorySize">
        <value>4096</value>
    </property>
   </bean>
 <bean id="urlMapping"
  class="org.springframework.web.servlet.handler.SimpleUrlHandlerMapping">       
 <property name="mappings">           
  <props>               
  <prop key="/upload.htm">uploadController</prop>           
  </props>       
 </property>   
 </bean>
     <bean id="uploadController" class="FileUploadController">
      <property name="commandClass"><value>FileUploadBean</value></property>
      <property name="uploadDir"><value>E:/</value></property>
      <property name="formView"><value>fail</value></property>
  <property name="successView"><value>confirmation</value></property>
</bean>  
3：定义控制类，commandClass及方法。控制类中最重要的方法是initBinder()它给spring注册了一个编辑器对
request中的multipart实体进行处理，如果没有这个方法，上传将不能进行。
<--------------------------控制类------------------->
public class FileUploadController extends SimpleFormController {
    private static Log log =
        LogFactory.getLog(FileUploadController.class);
    private String uploadDir;//上传文件路径

    protected ModelAndView onSubmit(HttpServletRequest request,
            HttpServletResponse response, Object cmd, BindException errors)
            throws Exception {

            FileUploadBean bean = (FileUploadBean) cmd;
            byte[] bytes = bean.getFile();
          
            //cast to multipart file so we can get additional information
            MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;
            CommonsMultipartFile file = (CommonsMultipartFile) multipartRequest.getFile("file");

            String uploadDir = this.getUploadDir();

            File dirPath = new File(uploadDir);
            if (!dirPath.exists()) {
                dirPath.mkdirs();
            }
            String sep = System.getProperty("file.separator");
            if (log.isDebugEnabled()) {
                log.debug("uploading to: " + uploadDir + sep +
                file.getOriginalFilename());
                }
            File uploadedFile = new File(uploadDir + sep
                    + file.getOriginalFilename());
            FileCopyUtils.copy(bytes, uploadedFile);
            System.out.println("********************************");
            System.out.println(uploadedFile.getAbsolutePath());
            System.out.println(bytes.length);
            System.out.println("********************************");
           
     
        return new ModelAndView(getSuccessView() + ".jsp");
    }

    protected void initBinder(HttpServletRequest request,
            ServletRequestDataBinder binder) throws ServletException {
        binder.registerCustomEditor(byte[].class,
                new ByteArrayMultipartFileEditor());
    }
    public void setUploadDir(String uploadDir){
        this.uploadDir = uploadDir;
    }
    public String getUploadDir(){
        return this.uploadDir;
    }
}