ajax请求下载文件

    function download() {
        // 请求地址
        var url = "${baseURL}/portal/visitorrecord/visitorrecordPortalAction!uploadSignatureByWorkno.action";
        // 分装form表单
        var form = $("<form></form>").attr("action", url).attr("method", "post");
        // 封装参数
        form.append($("<input></input>").attr("type", "hidden").attr("name", "outPutPdf").attr("value", outPutPdf));
        form.append($("<input></input>").attr("type", "hidden").attr("name", "fileName").attr("value", fileName));
        // 提交
        form.appendTo('body').submit().remove();
    }
	
	
	
	
	
	后台：
	public void uploadSignatureByWorkno() throws Exception {
        HttpServletRequest request = ServletActionContext.getRequest();
        HttpServletResponse response = ServletActionContext.getResponse();
        //获取PDF模板路径
        String outPutPdf = request.getParameter("outPutPdf");
        if (outPutPdf != null && !"".equals(outPutPdf)) {
            // 下载本地文件
            String fileName = request.getParameter("fileName"); // 文件的默认保存名
            //System.out.println(fileName);
            // 读到流中
            InputStream inStream = new FileInputStream(outPutPdf);// 文件的存放路径
            // 设置输出的格式
            response.reset();
            String userAgent = request.getHeader("User-Agent");
            // 针对IE或者以IE为内核的浏览器：解决中文乱码问题
            if (userAgent.contains("MSIE") || userAgent.contains("Trident")) {
                fileName = java.net.URLEncoder.encode(fileName, "UTF-8");
            } else {
                // 非IE浏览器的处理：
                fileName = new String(fileName.getBytes("UTF-8"), "ISO-8859-1");
            }
            response.setHeader("Content-disposition",
                    String.format("attachment; filename=\"%s\"", fileName));
            response.setContentType("application/pdf;charset=utf-8");
            response.setCharacterEncoding("UTF-8");
            // 循环取出流中的数据
            byte[] b = new byte[100];
            int len;
            try {
                OutputStream out = response.getOutputStream();
                while ((len = inStream.read(b)) > 0)
                    out.write(b, 0, len);
                inStream.close();
                out.flush();
                out.close();
            } catch (IOException e) {
                LOGGER.error("文件下载出现异常Exception！", e);
            }
        } else {
            try {
                throw new Exception("未找到文件");
            } catch (Exception e) {
                LOGGER.error("未找到上传的文件！");
            }
        }

    }