Servlet下载文件

@Override
    public void init() throws ServletException {
        // 获取项目在文件系统中的根目录
        string = getServletContext().getRealPath(File.separator);
    }

@Override
    protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {
        //配置文件路径
        String filePath = string + "download" + File.separator + "18612.jpg";
        //通过UUID获取宇宙唯一文件名，并将其中‘-’连接符去掉
        String fileName=UUID.randomUUID().toString().replace("-", "");
        // 设置下载文件名
        response.setHeader("content-disposition",
                "attachment;filename="+fileName+".jpg");
        // 获取输出流
        ServletOutputStream outputStream = response.getOutputStream();
        // 把文件写入tomcat
        InputStream inputStream = new FileInputStream(new File(filePath));
        byte[] b = new byte[1024];
        int len = 0;
        while ((len = inputStream.read(b)) != -1) {
            //输出到浏览器
            outputStream.write(b, 0, len);
        }
        if (inputStream!=null) {
            inputStream.close();
        }
        if (outputStream!=null) {
            outputStream.close();
        }
    }