<代码>包com.sys.web.sesoion; 进口java.io.IOException; 进口java.io.PrintWriter; 进口javax.servlet.ServletException; 进口javax.servlet.http.HttpServlet; 进口javax.servlet.http.HttpServletRequest; 进口javax.servlet.http.HttpServletResponse; 进口java.awt.Graphics; 进口java.awt.image.BufferedImage; 进口java.util.Random; 进口javax.imageio.ImageIO; 进口javax.servlet.http.HttpSession; 公开课CheckCodeServlet扩展HttpServlet { 公共空间doGet (HttpServletRequest请求,HttpServletResponse响应) 抛出ServletException IOException { BufferedImage图像=new BufferedImage (BufferedImage.TYPE_INT_RGB 50, 25日); 图g=image.getGraphics (); g.drawString (Token.getNum () 15 15); ImageIO.write(图片,JPG, response.getOutputStream ()); response.setHeader(“到期”,“1”); response.setHeader (“cache - control”、“no - cache”);//没有缓成 response.setHeader(“杂注”,“no - cache”); } }//用于产生随机数 类标记{ 公共静态字符串getNum () { 随机r=新的随机(); int num=r.nextInt (10000); 返回num + "; } }代码>