javaweb Servlet 下载文件

public class DownServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String realPath = "D:\Java\javaweb-02-servlet\downFileServlet\src\main\resources\1.png";
        System.out.println("下载的路径：" + realPath);
        String fileName = realPath.substring(realPath.lastIndexOf("\") + 1);
        resp.setHeader("Content-Disposition","attachment;filename="+URLEncoder.encode(fileName,"UTF-8"));
        FileInputStream in = new FileInputStream(realPath);
        int len = 0;
        byte[] buffer = new byte[1024];
        ServletOutputStream out = resp.getOutputStream();
        while ((len=in.read(buffer))>0){
            out.write(buffer,0,len);
        }
        in.close();
        out.close();
    }
}