html - 使用多部分/表单数据时如何从请求中获取字符串参数？

Question

<分区>

Answer 1

这是因为当你有表单 enctype="multipart/form-data" 时。您无法使用 request.getParameter("paramnName"); 获取其他表单字段。它总是会给你 NULL。

您必须使用 FormItem 的 isFormField() 来检查其常规字段或文件。

例子:

        try {
            ServletFileUpload upload = new ServletFileUpload();
            response.setContentType("text/plain"); 

            FileItemIterator iterator = upload.getItemIterator(request);

            while (iterator.hasNext()) {
              FileItemStream item = iterator.next();

              InputStream stream = item.openStream();

              if (item.isFormField()) {
                  System.out.println("Got a form field: " + item.getFieldName()  + " " +item);

              } else{
                  System.out.println("Got an uploaded file: " + item.getFieldName() +
                          ", name = " + item.getName());
                int len;
                byte[] buffer = new byte[8192];
                while ((len = stream.read(buffer, 0, buffer.length)) != -1) {

                  response.getOutputStream().write(buffer, 0, len);

                }

            }

        }
} catch (FileUploadException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}