session校验图片认证码

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生成验证码的servlet

public class ImgServlet extends HttpServlet {private static final long serialVersionUID = 1L;public static final int WIDTH = 120;public static final int HEIGHT = 25;protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {BufferedImage image = new BufferedImage(WIDTH,HEIGHT,BufferedImage.TYPE_INT_RGB);Graphics g = image.getGraphics();//1、设置背景色setBackGroud(g);//2.设置边框setBorder(g);//3.画干扰线drawRandomLine(g);//4.写随机数String random = drawRandomNum((Graphics2D)g);request.getSession().setAttribute("checkcode", random);//5.图形写给浏览器 response.setContentType("image/jpeg");//发图控制浏览器不要缓存response.setDateHeader("expries", -1);response.setHeader("cache-control", "no-cache");response.setHeader("Pragma", "no-cache");ImageIO.write(image, "jpg", response.getOutputStream());}private void setBackGroud(Graphics g) {g.setColor(Color.WHITE);//填充矩形g.fillRect(0, 0, WIDTH, HEIGHT);}private void setBorder(Graphics g) {g.setColor(Color.BLUE);g.drawRect(1, 1, WIDTH-2, HEIGHT-2);}private void drawRandomLine(Graphics g) {g.setColor(Color.GREEN);for(int i=0; i<5; i++){int x1 = new Random().nextInt(WIDTH);int y1 = new Random().nextInt(HEIGHT);int x2 = new Random().nextInt(WIDTH);int y2 = new Random().nextInt(HEIGHT);g.drawLine(x1, y1, x2, y2);}}//产生随机数并返回private String drawRandomNum(Graphics2D g) {g.setColor(Color.RED);g.setFont(new Font("宋体",Font.BOLD,20));//中文字所在区间  [\u4e00-\u9fa5]String base = "ABCDEFGHIJK";int x = 10;StringBuilder sb = new StringBuilder();for(int i=0; i<4; i++){//设置旋转角度int degree = new Random().nextInt()%30;//生成正负30内数String ch = base.charAt(new Random().nextInt(base.length()))+"";sb.append(ch);g.rotate(degree*Math.PI/180, x, 20);g.drawString(ch, x, 20);g.rotate(-degree*Math.PI/180, x, 20);//旋转回去x+=30;}return sb.toString();}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}}

提交表单

<html><head><meta charset="UTF-8"><title>Insert title here</title><script type="text/javascript">//实现图片转换的函数/* function changeImage(img){img.src = img.src+"?"+new Date().getTime();} */</script></head><body><form action="/day07/ImgCheck">用户名：<input type="text" name="username"><br>密    码：<input type="password" name="password"><br>验证码：<input type="text" name="checkcode"><img src="/day07/ImgServlet" onclick="this.src=this.src+'?'+new Date().getTime()" alt="换一张" style="cursor:pointer"><br><input type="submit" value="提交"></form></body></html>

验证的servlet

public class ImgCheck extends HttpServlet {private static final long serialVersionUID = 1L;protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {String c_checkcode = request.getParameter("checkcode");String s_checkcode = (String) request.getSession().getAttribute("checkcode");if(c_checkcode!=null && s_checkcode!=null && c_checkcode.equals(s_checkcode)){System.out.println("登陆成功");}else{System.out.println("验证失败");}}protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {doGet(request,response);}}

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