后台通过读取流的形式，实现下载功能

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jsp前台：jsp代码内潜入隐藏的form

                 <div class="accordion"><map name="FPMap0"><area  href="#" onclick="downloads();"  shape="rect" coords="7, 198, 181, 250"></map><ul style="display: inline-block;"><img src="${ctx}/images/lc.gif"  usemap="#FPMap0"/></ul></div><span style="color:#ff0000;"><form id="uploadForm" action="${ctx}/upload/downloadFile" method="post"><input type="hidden" name="fileName" id="fileName" /></form></span>

提交form的js 方法：

<span style="white-space:pre"></span><pre name="code" class="javascript">function downloads() {var fileName="密码重置受理表.doc";$("#fileName").val(fileName);$("#uploadForm").submit();}

controllor 层方法实现

@RequestMapping("/downloadFile")    public String download(String fileName, HttpServletResponse response) {        try {            String path = getRequest().getSession().getServletContext().getRealPath("/") + "docs/" + fileName;            logger.info("#downloadFile#path=" + path);            File file = new File(path);            response.reset();            response.setContentType("application/octet-stream;charset=UTF-8");            response.addHeader("Content-Length", "" + file.length());            String agent = getRequest().getHeader("USER-AGENT");            /*if (null != agent && -1 != agent.indexOf("MSIE") || null != agent && -1 != agent.indexOf("Trident")) {// ie                fileName = java.net.URLEncoder.encode(fileName, "UTF8");            } else if (null != agent && -1 != agent.indexOf("Mozilla")) {// 火狐,chrome等                fileName = new String(fileName.getBytes("UTF-8"), "iso-8859-1");            }*/            fileName =  new String(fileName.getBytes("gbk"), "iso-8859-1");            response.setHeader("Content-disposition", "attachment; filename=" + fileName);            InputStream inputStream = new FileInputStream(file);            OutputStream os = response.getOutputStream();            byte[] b = new byte[2048];            int length;            while ((length = inputStream.read(b)) > 0) {                os.write(b, 0, length);            }            // 这里主要关闭。            os.close();            inputStream.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        // 返回值要注意，要不然就出现下面这句错误！        // java+getOutputStream() has already been called for this response        return null;    }

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