protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setCharacterEncoding("UTF-8");//设置服务器的编码，默认是ISO-8859-1
        response.setContentType("text/html; charset = utf-8");//告诉浏览器服务器的编码格式
        response.getWriter().write("你好，JAVA");
    }

 protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        ServletOutputStream out=response.getOutputStream();
        File file=new File("图片路径");
        FileInputStream fi = new FileInputStream(file);
        byte[] buf = new byte[1024];
        int len = 0;
        while ((len = fi.read(buf)) != -1) {
            out.write(buf, 0, len); // 将数组中的指定长度的数据写入到输出流中。
        }
        fi.close();
        out.close();
    }