文件上传需要用到阿帕奇的commons-fileupload.jar组件，本帖带有附件
将commons-fileupload.jar导入WEB-INF/lib下
 
Servlet类，记住要在XML中作相应的配置。
保存路径为该项目下temp路径
public class Upload extends HttpServlet {

public void doPost(HttpServletRequest request, HttpServletResponse response)
      throws IOException, ServletException {
    parseRequest(request);
    
  }

public HashMap parseRequest(HttpServletRequest request) {
     HashMap<String,String> paramMap = new HashMap<String,String>();
     DiskFileUpload dfu = new DiskFileUpload(); //获取文件上传处理对象.
     dfu.setSizeMax(1024 * 1024 * 100);//设置允许上传文件大小上限.
     dfu.setSizeThreshold(4096);//设置缓冲区大小.
     dfu.setRepositoryPath(this.getServletContext().getRealPath("/temp/buffer"));//设置临时文件夹.
     try {
         List list = dfu.parseRequest(request);//解析request.
         Iterator it = list.iterator();
         while (it.hasNext()) {
             FileItem fi = (FileItem) it.next();
             if (fi.isFormField()) {//如果是普通文本.
                 paramMap.put(fi.getFieldName(), fi.getString());
             } else {//否则是文件.
                 String tmpFileName = "";
                 if (!fi.getName().equals("")) {// 如果有传文件.
                     tmpFileName = FileName.getRndFileName(fi.getName()); 
                   //将文件保存到服务器.
                     fi.write(new File(this.getServletContext().getRealPath("/temp/" + tmpFileName)));
                 }
                 paramMap.put(fi.getFieldName(), tmpFileName);
             } }    
     } catch (Exception e) {     e.printStackTrace();    }
        return paramMap;
     }

}
 
JSP中的上传构建，将表单提交到之前Servlet的地址
<body>
     <form name="myform" id="myform" action="./servlet/fileupload" method="post" enctype="multipart/form-data">
             File:<br>
             <input type="file" name="myfile"><br>
             <br>
             <input type="submit" name="submit" value="Commit">
        </form>

    </body>