http://www.cnblogs.com/mbailing/archive/2010/10/26/1861712.html

这里有一些资料，希望对你有用。

publicvoid doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setCharacterEncoding("GBK");
        request.setCharacterEncoding("GBK");
        response.setContentType("text/html");
        String URL ="jdbc:mysql://localhost:3306/test?user=root&"
                +"password=admin&useUnicode=true&characterEncoding=gbk";
        Connection conn =null;
        Statement stmt =null;
        // 判断提交过来的表单是否为文件上传表单
boolean isMultipart = ServletFileUpload.isMultipartContent(request);
        String name =null;
        String fileName =null;
        String path =null;
        if (isMultipart) {
            // 构造文件上传处理对象
            FileItemFactory factory =new DiskFileItemFactory();
            ServletFileUpload upload =new ServletFileUpload(factory);
            Iterator items;
            try {
                // 解析出表单中提交的所有文件内容
                items = upload.parseRequest(request).iterator();
                while (items.hasNext()) {
                    FileItem item = (FileItem) items.next();
                    name = item.getName();
                    // 获取文件名
                    fileName = name.substring(name.lastIndexOf('\\') +1, name
                            .length());
                    // 获取文件上传后的存储路径(上传后的文件将存储到当前应用项目的file文件夹中)
                    // File.separatorChar相当于/
                    String realPath = request.getRealPath("upload");
                    path = realPath + File.separator + fileName;
                    File uploadFile =new File(path);
                    item.write(uploadFile);
                    String sql ="insert into file(filename,filepath) value('"+fileName+"','"+path+"')";
                    Class.forName("com.mysql.jdbc.Driver");
                    conn = DriverManager.getConnection(URL);
                    stmt = conn.createStatement();
                    stmt.execute(sql);
                    PrintWriter out = response.getWriter();
                    out.println("<p align='center'><font size='2'>上传的文件为："
                            + name +"<br>");
                    out.println("<font size='2'>保存的路径是："+ path +"</p>");
                }

            } catch (Exception e) {
            }
        }
    }