enctype="multipart/form-data"的表单无法获取表单中除了type=file以外的其他参数 commons-fileupload 获取除file外其他参数

                        <form id="uploadFileForm" action="UploadServlet" target="hiddenFrame" method="post" enctype="multipart/form-data">
                            <input id="fileInput" type="file" onchange="uploadFile();" name="upload" >
                            <input type="hidden" value="/image/" name="directory">
                        </form>

package UI.FileManage;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.util.Iterator;
import java.util.List;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

public class UploadServlet extends HttpServlet {

    @SuppressWarnings("unchecked")
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=UTF-8");
        String errorMessage = null;
        try {
            DiskFileItemFactory fac = new DiskFileItemFactory();
            ServletFileUpload upload = new ServletFileUpload(fac);
            upload.setHeaderEncoding("utf-8");
            List fileList = null;
            fileList = upload.parseRequest(request);

            String dir = ((FileItem)fileList.get(1)).getString();   //获取directory参数
            if (dir == null) {
                dir = "/";
            }
            String savePath = getServletContext().getRealPath("/test" + dir);
            System.out.println("save at:" + savePath);
            File f1 = new File(savePath);
            if (!f1.exists()) {
                f1.mkdirs();
            }
            
            Iterator<FileItem> it = fileList.iterator();
            String name = "";
            while (it.hasNext()) {
                FileItem item = it.next();
                if (!item.isFormField()) {
                    name = item.getName();
                    File file = new File(savePath + File.separatorChar + name);
                    if (file.exists()) {
                        errorMessage = "该文件已经存在！请重命名后再上传。";
                    }
                    item.write(file);
                    item.delete();  //释放输出流
                }
            }
            if (errorMessage == null) {
                response.getWriter().print("<script> parent.finishUploading(1);</script>");
            } else {
                response.getWriter().print("<script> parent.finishUploading(0,'" + errorMessage + "');</script>");
            }
        } catch (Exception exception) {
            response.getWriter().print("<script> parent.finishUploading(0,'上传失败，请重试。');</script>");
        }
    }
}