servlet 验证码

傷城~ 2022-06-13 13:53 154阅读 0赞

## 手工实现 ##

import java.awt.Color;
    import java.awt.Font;
    import java.awt.Graphics;
    import java.awt.Image;
    import java.awt.image.BufferedImage;
    import java.io.IOException;
    import java.util.Random;
    
    import javax.imageio.ImageIO;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import cn.dsna.util.images.ValidateCode;
    
    public class Demo3 extends HttpServlet{ 
    
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp)
                throws ServletException, IOException {
            ValidateCode vc = new ValidateCode(110,50);
            vc.write(resp.getOutputStream());
            int width = 110;
            int height = 25;
            BufferedImage img = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
    
            //创建画笔
            Graphics g = img.getGraphics();
            //上背景色
            g.setColor(Color.PINK);
            g.fillRect(1, 1, width-2, height-2);
            //给边框颜色
            g.setColor(Color.RED);
            g.drawRect(1, 1, width, height);
    
            //设置文字
            g.setColor(Color.BLUE);
            g.setFont(new Font("宋体", Font.PLAIN,15));
            Random rand = new Random();
            int cnt = 20;
            for (int i=0; i<4; i++){
                g.drawString(rand.nextInt(10)+"", cnt, 20);
                cnt+=20;
            }
            for (int i=0; i<4; i++){
                g.drawLine(rand.nextInt(width), rand.nextInt(height),rand.nextInt(width), rand.nextInt(height));
            }
            //将图片以流对象输出到客户端
            ImageIO.write(img, "jpg", resp.getOutputStream());
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp)
                throws ServletException, IOException {
            // TODO 自动生成的方法存根
            super.doPost(req, resp);
        }
    
    }

### html显示验证码 ###

<!DOCTYPE html>
    <html>
      <head>
        <title>Login.html</title>
        <meta name="keywords" content="keyword1,keyword2,keyword3">
        <meta name="description" content="this is my page">
        <meta name="content-type" content="text/html; charset=UTF-8">
    
        
    
    <script type="text/javascript"> function changeCode(){ var img = document.getElementsByTagName("img")[0]; img.src="/day1/demo1?time="+new Date().getTime(); } </script>
      </head>
    
      <body>
        <form action="#" method="post">
            用户名:<input type="text" ><br>
            密码：<input type="password" ><br>
            验证码:<input type="text" >
            <img src="/day1/demo1" onclick="changeCode()"/><a href="javascript:changeCode()">看不清 换一张</a><br>
            <input type="submit" value="登入"/><br>
        </form>
      </body>
    </html>

## 通过jar包实现 ##

就换成两行代码即可，都实现好了直接用

package demo2;
    
    import java.awt.Color;
    import java.awt.Font;
    import java.awt.Graphics;
    import java.awt.Image;
    import java.awt.image.BufferedImage;
    import java.io.IOException;
    import java.util.Random;
    
    import javax.imageio.ImageIO;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    import cn.dsna.util.images.ValidateCode;
    
    public class Demo3 extends HttpServlet{ 
    
        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp)
                throws ServletException, IOException {
            ValidateCode vc = new ValidateCode(110,50);
            vc.write(resp.getOutputStream());
        }
    
        @Override
        protected void doPost(HttpServletRequest req, HttpServletResponse resp)
                throws ServletException, IOException {
            // TODO 自动生成的方法存根
            super.doPost(req, resp);
        }
    
    }