简易的验证码实现

第一种:随机图片

第二种;代码生成

　　　　java代码：

@WebServlet("/checkCodeServlet")
public class checkCodeServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {


    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        int width = 100;
        int height = 50;

        //1、创建一对象，在内存中图片（验证码图片对象）
        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
        //2.美化图片
        Graphics g = image.getGraphics();//创建画笔对象
        g.setColor(Color.pink);//设置画笔的颜色
        g.fillRect(0,0,width,height);

        //2.2画边框
        g.setColor(Color.blue);
        g.drawRect(0,0,width-1,height-1);

        String str = "ABCDEFGHKIJMNOPQRSTUWXYZabcdefghijklmnopqrstuwxyz0123456789";
        //生成随机角标
        Random random = new Random();
        for (int i = 1; i<=4;i++) {
            int index = random.nextInt(str.length());
            //获取字符
            char ch = str.charAt(index);
            //写验证码
            g.drawString(ch+"",width/5*i,height/2);
        }
        //画干扰线
        g.setColor(Color.green);
        for (int i = 0; i < 10; i++) {
            int x1 = random.nextInt(width);
            int x2 = random.nextInt(width);

            int y1 = random.nextInt(width);
            int y2 = random.nextInt(width);
            g.drawLine(x1,x2,y1,y2);
        }
        //3.将图片输出到页面
        ImageIO.write(image,"jpg",response.getOutputStream());
    }
}

　　　　html页面;

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script>
        /*
        * 分析：
        *      点击图片或者超链接，需要换一张图片
        *      1.给超链接和图片添加点击事件
        *      2.重新设置图片的src属性值*/
        window.onload = function () {
            //获取图片对象
            var image = document.getElementById("checkCode");
            image.onclick = function () {
                //加时间戳
                var date = new Date().getTime();
                image.src="/day17_tomact_war_exploded/checkCodeServlet?"+date;
            }
        }
    </script>
</head>
<body>
    <img src="/day17_tomact_war_exploded/checkCodeServlet" id="checkCode">
    <a id="change" href="javascript:void(0)">看不清换一张图片？</a>
</body>
</html>

 

验证码插件:

@WebServlet("/checkCode")
public class CheckCodeServlet extends HttpServlet {
    public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {
        
        //服务器通知浏览器不要缓存
        response.setHeader("pragma","no-cache");
        response.setHeader("cache-control","no-cache");
        response.setHeader("expires","0");
        
        //在内存中创建一个长80，宽30的图片，默认黑色背景
        //参数一：长
        //参数二：宽
        //参数三：颜色
        int width = 80;
        int height = 30;
        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
        
        //获取画笔
        Graphics g = image.getGraphics();
        //设置画笔颜色为灰色
        g.setColor(Color.GRAY);
        //填充图片
        g.fillRect(0,0, width,height);
        
        //产生4个随机验证码，12Ey
        String checkCode = getCheckCode();
        //将验证码放入HttpSession中
        request.getSession().setAttribute("CHECKCODE_SERVER",checkCode);
        
        //设置画笔颜色为黄色
        g.setColor(Color.YELLOW);
        //设置字体的小大
        g.setFont(new Font("黑体",Font.BOLD,24));
        //向图片上写入验证码
        g.drawString(checkCode,15,25);
        
        //将内存中的图片输出到浏览器
        //参数一：图片对象
        //参数二：图片的格式，如PNG,JPG,GIF
        //参数三：图片输出到哪里去
        ImageIO.write(image,"PNG",response.getOutputStream());
    }
    /**
     * 产生4位随机字符串 
     */
    private String getCheckCode() {
        String base = "0123456789ABCDEFGabcdefg";
        int size = base.length();
        Random r = new Random();
        StringBuffer sb = new StringBuffer();
        for(int i=1;i<=4;i++){
            //产生0到size-1的随机值
            int index = r.nextInt(size);
            //在base字符串中获取下标为index的字符
            char c = base.charAt(index);
            //将c放入到StringBuffer中去
            sb.append(c);
        }
        return sb.toString();
    }
    public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doGet(request,response);
    }
}

 

 

 posted on 2019-11-06 22:31  爱舔奶盖的小野狼  阅读(147)  评论(0)    收藏  举报