java后台下载方法

    public void fileDownload() throws UnsupportedEncodingException {
        String fileidd= this.getParameter("获取ID");
        SysFile sysFile = sysFileManager.getById(根据id(fileidd)查询);
        File file = new File(AppUtil.getAppAbsolutePath()+sysFile.getPicpath()//获取路径);
        if (file.exists()) {
            this.getResponse().setContentType("application/force-download");// 设置强制下载不打开
            this.getResponse().addHeader("Content-Disposition", "attachment;fileName="+ java.net.URLEncoder.encode(sysFile.getFilename()//获取文件名, "UTF-8"));// 设置文件名

            byte[] buffer = new byte[1024];
            FileInputStream fis = null;
            BufferedInputStream bis = null;
            try {
                fis = new FileInputStream(file);
                bis = new BufferedInputStream(fis);
                OutputStream os = this.getResponse().getOutputStream();
                int i = bis.read(buffer);
                while (i != -1) {
                    os.write(buffer, 0, i);
                    i = bis.read(buffer);
                }
                System.out.println("success");
            } catch (Exception e) {
                e.printStackTrace();
            } finally {
                if (bis != null) {
                    try {
                        bis.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
                if (fis != null) {
                    try {
                        fis.close();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        }