解决当FORM的ENCTYPE="multipart/form-data" 时request.getParameter()获取不到值的方法

部分转载于:

http://blog.csdn.net/georgejin/article/details/1706647

http://www.cnblogs.com/loveyunk/p/6089032.html

http://www.cnblogs.com/greenteaone/p/4186619.html

from表单中向后台传递参数的同时要上传文件，所以ENCTYPE="multipart/form-data" 必须要加在form里面,可是这样的话，我在servlet里面用request.getParameter()方法无论如何都只是获得null值.

我这里使用的是commons fileupload的jar包(commons-fileupload-1.2.jar).

先附录之前写的上传文件的工具类:

 public class FileUploadAndDown {

     private Logger logger = Logger.getLogger(FileUploadAndDown.class);

     public String upload(ServletConfig servletconfig, HttpServletRequest request)throws FileUploadException{
         HttpSession session = request.getSession();
         String username = session.getAttribute("username").toString();
         DiskFileUpload fu = new DiskFileUpload();
         // 判断表单是否设置了mutipart/form-data
         boolean isMultipart = DiskFileUpload.isMultipartContent(request);
         if (!isMultipart){
             return null;
         }else{
             fu.setHeaderEncoding(request.getCharacterEncoding());
             // 设置允许用户上传文件大小,单位:字节
             fu.setSizeMax(10*1024*1024);
             // 设置最多只允许在内存中存储的数据,单位:字节
             fu.setSizeThreshold(4*1024*1024);
             // 设置一旦文件大小超过getSizeThreshold()的值时数据存放在硬盘的目录
             String temp = System.getProperty("user.home")+File.separator+"catalogupload";
             fu.setRepositoryPath(temp);
             File file = new File(temp);
             if (!file.exists() || !file.isDirectory()) {
                 file.mkdir();
             }
             // 开始读取上传信息

             List fileItems = fu.parseRequest(request);
             // 依次处理每个上传的文件

             Iterator iter = fileItems.iterator();
             // 如果需要上传多个文件，将if改称while即可
             while(iter.hasNext()) {
                 FileItem item = (FileItem) iter.next();
                 // 忽略其他不是文件域的所有表单信息

                 if (!item.isFormField()) {
                     String name = item.getName();
                     String time = DateUtil.getDateTime("yyyyMMddHHmmss");
                     name = username + "_" + time + FileNameUtil.extractFileExt(name);
                     try {
                         String namepath = servletconfig.getServletContext().getRealPath("poster");
                         file = new File(namepath);
                         if(!file.exists()){
                             file.mkdirs();
                         }
                         name = namepath+File.separator+name;
                         item.write(new File(name));
                         logger.info("上传海报名为:" + name);
                         return name;
                     } catch (Exception e) {
                         logger.error("上传海报保存异常" + e.getMessage());
                         return null;
                     }
                 }
             }
         }
         return "";
     }
 }

对应的jsp页面

         <form name="form1" action="deleteMmobject.do" method="post" enctype="multipart/form-data" target="displayprocess" >
             导入要删除列表文件 &nbsp;&nbsp;&nbsp;
             <input type="hidden" id="deleteFlagHidden" name="deleteFlagHidden" value="" />
             <input type="hidden" name="action" value="" />

             <input type="file" name="filepath" />
             <input name="deleteMmobject_radio" id="selfDelete" type="radio" value="自删除" onclick="selfDeleteFun()"; checked />自删除
             <input name="deleteMmobject_radio" id="sendToBoDelete" type="radio" value="同时下发删除到下游" onclick="sendToBoDeleteFun()" />同时下发删除到下游
             <input type="button" value="确定" onclick="deleteFun()"/>
             <!-- <input type="submit"  value="确定" /> -->
         </form>

通过servlet里面用request.getParameter("id名称")方法无论如何都只是获得null值.   通过更换上传依赖的jar包(jspsmartupload.jar)

新加代码如下:

     public Map<String,String> uploadUseJspSmart(ServletConfig servletconfig, HttpServletRequest request, HttpServletResponse response)throws FileUploadException{
         Map<String,String> uploadParametersMap = new HashMap<String,String>();
         HttpSession session = request.getSession();
         String username = session.getAttribute("username").toString();

         com.jspsmart.upload.SmartUpload smartUpload = new com.jspsmart.upload.SmartUpload();
         File file = null;
         String fileName = null;
         try {
             smartUpload.initialize(servletconfig, request, response);
             smartUpload.setTotalMaxFileSize(100000000);
             smartUpload.setAllowedFilesList("txt,excel");
             smartUpload.setDeniedFilesList("exe,bat,jsp,htm,html,,");

             smartUpload.upload();
             // 得到上传的文件对象
             com.jspsmart.upload.File smartFile = smartUpload.getFiles().getFile(0);

             fileName = smartFile.getFileName();
             String time = DateUtil.getDateTime("yyyyMMddHHmmss");
             fileName = username + "_" + time + FileNameUtil.extractFileExt(fileName);
             String namepath = System.getProperty("user.home")+File.separator+"catalogupload";

             file = new File(namepath);
             if(!file.exists()){
                 file.mkdirs();
             }
             fileName = namepath+File.separator+fileName;
             smartFile.saveAs(fileName);
             logger.info("通过JspSamrt上传文件名为:" + fileName+"成功");
             //这里可以顺利得到jsp页面form表单中对应的"deleteFlagHidden"参数
             String deleteFlagHidden = smartUpload.getRequest().getParameter("deleteFlagHidden");
             uploadParametersMap.put("fileName", fileName);
             uploadParametersMap.put("deleteFlagHidden", deleteFlagHidden);
             return uploadParametersMap;
         } catch (Exception e1) {
             e1.printStackTrace();
             logger.info("通过JspSamrt上传文件名为:" + fileName+"失败");
         }
         return null;
     }