downloadTemplate('exportExcelServlet.exportExcelServlet','filename',id);

/*** js创建form表单的提交（我的页面没写form表单），采用post方式提交（这里不用改）* @param action action映射地址：web.xml配置了Servlet响应类* @param type： 名称* @param value：表单传给后台的值*/
function downloadTemplate(action, type, value){var form = document.createElement('form');document.body.appendChild(form);form.style.display = "none";form.action = action;form.id = 'excel';form.method = 'post';var newElement = document.createElement("input");  newElement.setAttribute("type","hidden");  newElement.name = type;newElement.value = value;form.appendChild(newElement); form.submit();
}

/*** web.xml：提交Form表单后，响应的处理类* 响应以.exportExcelServlet结尾的Action* @param type： 名称* @param value：表单传给后台的值*/
<servlet><servlet-name>exportExcelServlet</servlet-name><servlet-class>Servlet类所在路径.ExportExcelServlet</servlet-class><load-on-startup>3</load-on-startup>
</servlet><servlet-mapping><servlet-name>exportExcelServlet</servlet-name><url-pattern>*.exportExcelServlet</url-pattern>
</servlet-mapping>

public class ExportExcelServlet extends HttpServlet {/*** serialVersionUID*/private static final long serialVersionUID = -4541729035831587727L;@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {doPost(req, resp);}@Overrideprotected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {//form表单的value传的值Long id = Long.valueOf(req.getParameter("filename"));//调用生成Excel的函数，它生成Excel保存到服务器
        exportExcel(id);try{// 清空输出流
            resp.reset();//获取上面生成Excel的路径String filePath = "路径";//设置编码方式resp.setCharacterEncoding("UTF-8");  // 设定输出文件头resp.setHeader("Content-disposition", "attachment; filename=" + URLEncoder.encode("自定义下载保存的名称","UTF-8"));resp.setContentType("application/ms-excel");// 流的方式读取保存到服务器的ExcelDataInputStream in = new DataInputStream(new FileInputStream(new File(filePath)));// 流的方式输出到浏览器，可下载OutputStream out = resp.getOutputStream();int bytes = 0;byte[] bufferOut = new byte[1024];  while ((bytes = in.read(bufferOut)) != -1) {  out.write(bufferOut, 0, bytes);  }out.close();in.close();//删除刚才保存到服务器的路径的Excel
            RemoveDirectoryUtil.delSingleFile(filePath);} catch(Exception e){e.printStackTrace();}}}