java实现动态验证码

代码:

package com.icis.servlet;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

@WebServlet("/vericode")
public class  VeriCodeServlet extends HttpServlet {
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("UTF-8");
        response.setContentType("text/html;charset=utf-8");
        System.out.println(66666);
        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
        //2.1 填充背景色
        Graphics g = image.getGraphics();//画笔对象
        g.setColor(Color.PINK);//设置画笔颜色
        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 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghigklmnopqrstuvwxyz0123456789";
        //String str = "1234567890";
        //生成随机角标
        Random ran = new Random();
        //存储验证码字符串
        StringBuilder stringBuilder = new StringBuilder();

        for (int i = 1; i <= 4; i++) {
            int index = ran.nextInt(str.length());
            //获取字符
            char ch = str.charAt(index);//随机字符
            //
            stringBuilder.append(ch);
            //2.3写验证码
            g.drawString(ch + "", width / 5 * i, height / 2);
        }
        //创建session
        HttpSession session = request.getSession();
        //session存储验证码到域
        session.setAttribute("verycode", stringBuilder.toString());

        //2.4画干扰线
        g.setColor(Color.GREEN);

        //随机生成坐标点

        for (int i = 0; i < 10; i++) {
            int x1 = ran.nextInt(width);
            int x2 = ran.nextInt(width);

            int y1 = ran.nextInt(height);
            int y2 = ran.nextInt(height);
            g.drawLine(x1, y1, x2, y2);
        }


        //3.将图片输出到页面展示
        ImageIO.write(image, "jpg", response.getOutputStream());


    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}

前端html

 <div class="form-inline">
            <label for="vcode">验证码：</label>
            <input type="text" name="verifycode" class="form-control" id="verifycode" placeholder="请输入验证码"
                   style="width: 120px;"/>
            <a href="javascript:refreshCode()"><img src="vericode" title="看不清点击刷新" id="vcode"/></a>
        </div>

javacript

<script>
    function refreshCode() {
        var img = document.getElementById("vcode");
        img.src = "vericode?" + Math.random();

    }
</script>

效果