servlet 验证码-蒲公英云

servlet 验证码

傷城~ 2022-06-13 13:53 264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">
    <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->
<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);
    }
}