JSP无法获取表单元素的值

Question

添加了一个文件域,因为要上传文件,然后在JSP页面中就获取不到值了,用SmartUpload对象的getRequest方法仍然获取不到值,我想请问这是什么原因,怎么解决

Answer 1

常见的错误原因是
1、form的method没有设为post。
2、form的enctype没有设为"multipart/form-data"。

Answer 2

public void doAdd_books(HttpServletRequest request,HttpServletResponse response)
throws ServletException, IOException {try {DiskFileUpload fu = new DiskFileUpload();// 代表当前上传文件磁盘对象// 设置最大文件尺寸，这里是4MBfu.setSizeMax(4194304);// 设置缓冲区大小，这里是4kb
fu.setSizeThreshold(4096);// 设置临时目录：fu.setRepositoryPath("D:\\");// 得到所有的文件：List fileItems= fu.parseRequest(request);// 解析请求对象Iterator i = fileItems.iterator();// 依次处理每一个文件：
books_bean books = new books_bean();while (i != null && i.hasNext()) {FileItem item = (FileItem) i.next();
// 简单的表单if (item.isFormField()) {System.out.print("form field:");System.out.print("==" + item.getFieldName() + " ");System.out.print(item.getString());String param_name = item.getFieldName();
if (param_name.equals("book_name")) {books.setBook_name(new String(item.getString().getBytes("ISO-8859-1")));} else if (param_name.equals("book_author")) {books.setBook_author(new String(item.getString().getBytes("ISO-8859-1")));} else if (param_name.equals("book_concern")) {
books.setBook_concern(new String(item.getString().getBytes("ISO-8859-1")));} else if (param_name.equals("fk_group_id")) {books.setFk_group_id(Integer.parseInt(item.getString()));}
else if (param_name.equals("book_market_price")) {books.setBook_market_price(Float.parseFloat(item.getString()));} else if (param_name.equals("book_favourable_price")) {
books.setBook_favourable_price(Float.parseFloat(item.getString()));} else if (param_name.equals("book_image")) {books.setBook_image(new String(item.getString().getBytes("ISO-8859-1")));}
else if (param_name.equals("book_info")) {books.setBook_info(new String(item.getString().getBytes("ISO-8859-1")));}}// 文件域else if (!item.isFormField()) {String fileName = item.getName().substring(item.getName().lastIndexOf("\\"));books.setBook_image("image/"+fileName.substring(1,fileName.length()));BufferedInputStream in = new BufferedInputStream(item.getInputStream());// 文件存储在工程的upload
//太多了，写不完