java简单实现文件下载

//文件下载
 public void download(HttpServletRequest request,
                      HttpServletResponse response, String storeName, String contentType)throws Exception{
     request.setCharacterEncoding("UTF-8");
     BufferedInputStream bis = null;
     BufferedOutputStream bos = null;

     //获取项目根目录
     String ctxPath = request.getSession().getServletContext()
             .getRealPath("/resource/download/");

     //获取下载文件露肩
     String downLoadPath = ctxPath+storeName;
     //获取文件的长度
     long fileLength = new File(downLoadPath).length();

     //设置文件输出类型
     response.setContentType("application/octet-stream");
     response.setHeader("Content-disposition", "attachment; filename="
             + new String(storeName.getBytes("utf-8"), "ISO8859-1"));
     //设置输出长度
     response.setHeader("Content-Length", String.valueOf(fileLength));
     //获取输入流
     bis = new BufferedInputStream(new FileInputStream(downLoadPath));
     //输出流
     bos = new BufferedOutputStream(response.getOutputStream());
     byte[] buff = new byte[2048];
     int bytesRead;
     while (-1 != (bytesRead = bis.read(buff, 0, buff.length))) {
         bos.write(buff, 0, bytesRead);
     }
     //关闭流
     bis.close();
     bos.close();
 }