The experience of using enctype="multipart/form-data" of form form

When using a form to transmit data, if the form adds the attribute enctype="multipart/form-data", then when the form request is passed to another jsp or servlet,
you cannot use request.getParameter() to get each form element of the value.
This can be used in general (API provided by the upload component):
boolean isMultipart = ServletFileUpload.isMultipartContent(request);
if (isMultipart) {
  // Create a factory for disk-based file items
  org.apache.commons.fileupload.FileItemFactory factory = new DiskFileItemFactory ();

  // Create a new file upload handler
  ServletFileUpload upload = new ServletFileUpload(factory);
  // Parse the request
  List /* FileItem */items = upload.parseRequest(request);

  // Process the uploaded items
  Iterator iter = items .iterator();

  while (iter.hasNext()) {
   org.apache.commons.fileupload.FileItem item = (org.apache.commons.fileupload.FileItem) iter
     .next();
   if (item.isFormField()) {
    String name = item.getFieldName();
    String value = item .getString("GBK");
    //out.println(name + "=" + value);
    params.put(name.toUpperCase(), value.trim());
   } ......
=== ===================================================== ===========================
When using multipart/form-data to upload, the request sent is different from the general http, and it needs to be converted before it can be read Other parameters.  
   
  If you use spring, it provides a MultiRequestResolver, just need:  
  MultipartHttpServletRequest multipartRequest = (MultipartHttpServletRequest) request;  
  Then you can read the parameters normally:  
  multipartRequest.getParameter("xxx");  
   
  以下是spring的处理方法，必须首先安装commons-fileupload组件：  
   
  public   MultipartHttpServletRequest   resolveMultipart(HttpServletRequest   request)   throws   MultipartException   {  
  DiskFileUpload   fileUpload   =   this.fileUpload;  
  String   enc   =   determineEncoding(request);  
   
  //   use   prototype   FileUpload   instance   if   the   request   specifies  
  //   its   own   encoding   that   does   not   match   the   default   encoding  
  if   (!enc.equals(this.defaultEncoding))   {  
  fileUpload   =   new   DiskFileUpload();  
  fileUpload.setSizeMax(this.fileUpload.getSizeMax());  
  fileUpload.setSizeThreshold(this.fileUpload.getSizeThreshold());  
  fileUpload.setRepositoryPath(this.fileUpload.getRepositoryPath());  
  fileUpload.setHeaderEncoding(enc);  
  }  
   
  try   {  
  List   fileItems   =   fileUpload.parseRequest(request);  
  Map   parameters   =   new   HashMap();  
  Map   multipartFiles   =   new   HashMap();  
  for   (Iterator   it   =   fileItems.iterator();   it.hasNext();)   {  
  FileItem   fileItem   =   (FileItem)   it.next();  
  if   (fileItem.isFormField())   {  
  String   value   =   null;  
  try   {  
  value   =   fileItem.getString(enc);  
  }  
  catch   (UnsupportedEncodingException   ex)   {  
  logger.warn("Could   not   decode   multipart   item   '"   +   fileItem.getFieldName()   +  
          "'   with   encoding   '"   +   enc   +   "':   using   platform   default");  
  value   =   fileItem.getString();  
  }  
  String[]   curParam   =   (String[])   parameters.get(fileItem.getFieldName());  
  if   (curParam   ==   null)   {  
  //   simple   form   field  
  parameters.put(fileItem.getFieldName(),   new   String[]   {   value   });  
  }  
  else   {  
  //   array   of   simple   form   fields  
  String[]   newParam   =   StringUtils.addStringToArray(curParam,   value);  
  parameters.put(fileItem.getFieldName(),   newParam);  
  }  
  }  
  else   {  
  //   multipart   file   field  
  CommonsMultipartFile   file   =   new   CommonsMultipartFile(fileItem);  
  multipartFiles.put(file.getName(),   file);  
  if   (logger.isDebugEnabled())   {  
  logger.debug("Found   multipart   file   ["   +   file.getName()   +   "]   of   size   "   +   file.getSize()   +  
          "   bytes   with   original   filename   ["   +   file.getOriginalFilename()   +   "],   stored   "   +  
          file.getStorageDescription());  
  }  
  }  
  }  
  /*****   注意   parameters   就是普通的text之类的字段的值   *****/  














    <td height="30" align="right">Upload business license image:</td>
    <td><INPUT TYPE="FILE" NAME="uploadfile" SIZE="34" onChange="checkimage()" ></td>
  </tr>
must add ENCTYPE="multipart/form-data".
The meaning of enctype="multipart/form-data" in the form is to set the MIME encoding of the form. By default, this encoding format is application/x-www-form-urlencoded, which cannot be used for file uploading; only when multipart/form-data is used, the file data can be completely transmitted, and the following operations are performed.
enctype=\"multipart/ form-data\" is to upload binary data; the value of input in the form is passed in binary format.
The value of the input in the form is passed in binary format, so the request will not get the value. That is to say, if this code is added, the transfer will be unsuccessful with request. When adding the

form value to the database, use the following:
SmartUpload su = new SmartUpload();//Create a new SmartUpload object
su.getRequest().getParameterValues (); Take the array value
su.getRequest().