JSP页面验证码实现

首先在JSP页面加上生成图片的链接

<img type="image" src="auth/authCode" id="codeImage" name="codeImage" style="cursor:pointer;"/>，src需要我们自己实现，实现逻辑如下

JSP页面验证码实现

运行后，jsp页面会发出"auth/code"请求生成验证码，并将验证码放置于session中用于验证，运行效果如下

JSP页面验证码实现

我们在jsp页面上加上输入验证码的输入框及提交按钮，点击按钮后进行验证码判断

JSP页面验证码实现

后台会比将收入的验证码与放置于session中的验证码进行比对，并输出结果给JSP页面进行相应处理，当判断为失败，则刷新验证码

JSP页面验证码实现

最后，相对完整的页面和逻辑都已实现，代码如下

JSP页面代码

<%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %>
<%@ page import="java.util.*" %>
<html>
<head>
    <title>Title</title>
</head>
<%--<script src="js/jquery.min.js"></script>--%>
<script src="https://libs.baidu.com/jquery/1.8.3/jquery.js"></script>
<script type="text/javascript">
    function submitForm() {
        var inputCode=$("#authCode").attr("value");
        var list={"inputCode":inputCode};
        $.ajax({
            //请求方式
            type : "POST",
            //请求的媒体类型
            contentType: "application/x-www-form-urlencoded",
            //请求地址
            url : "auth/checkCode",
            //数据，json字符串
            data :list,
            dataType:"json",
            //请求成功
            success : function(result) {
                alert(result);
                if(result=="1"){
                    alert("验证通过");
                }else{
                    alert("验证失败，重新刷新验证码");
                    flushAuthCode();
                }
            },
            //请求失败，包含具体的错误信息
            error : function(e){
                alert(e.responseText);
            }
        });
    }
    function flushAuthCode() {
        //重新刷新验证码
        $("#codeImage").attr("src","auth/authCode?abc="+Math.random());
    }

</script>
<body>

    <form id="authForm" action="checkCode">
        <input type="text" id="authCode" name="authCode">
        <img type="image" src="auth/authCode" id="codeImage" name="codeImage" style="cursor:pointer;"/>
        <button type="button" id="submitBtn" name="submitBtn" value="提交" onclick="submitForm()"/>
    </form>
</body>
</html>

后台代码

package com.founderit.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;

import javax.imageio.ImageIO;
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;

@Controller
@RequestMapping("auth")
public class Auth {
    private char[] codeSequence = { 'A', '1','B', 'C', '2','D','3', 'E','4', 'F', '5','G','6', 'H', '7','I', '8','J',
            'K',   '9' ,'L', '1','M',  '2','N',  'P', '3', 'Q', '4', 'R', 'S', 'T', 'U', 'V', 'W',
            'X', 'Y', 'Z'};
    @RequestMapping("authCode")
    public void getCode(HttpServletResponse response, HttpSession session) throws IOException {
        int width = 63;
        int height = 37;
        Random random = new Random();
        //设置response头信息
        //禁止缓存
        response.setHeader("Pragma", "No-cache");
        response.setHeader("Cache-Control", "no-cache");
        response.setDateHeader("Expires", 0);

        //生成缓冲区image类
        BufferedImage image = new BufferedImage(width, height, 1);
        //产生image类的Graphics用于绘制操作
        Graphics g = image.getGraphics();
        //Graphics类的样式
        g.setColor(this.getColor(200, 250));
        g.setFont(new Font("Times New Roman",0,28));
        g.fillRect(0, 0, width, height);
        //绘制干扰线
        for(int i=0;i<40;i++){
            g.setColor(this.getColor(130, 200));
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int x1 = random.nextInt(12);
            int y1 = random.nextInt(12);
            g.drawLine(x, y, x + x1, y + y1);
        }

        //绘制字符
        String strCode = "";
        for(int i=0;i<4;i++){
            String rand = String.valueOf(codeSequence[random.nextInt(codeSequence.length)]);
            strCode = strCode + rand;
            g.setColor(new Color(20+random.nextInt(110),20+random.nextInt(110),20+random.nextInt(110)));
            g.drawString(rand, 13*i+6, 28);
        }
        //将字符保存到session中用于前端的验证
        session.setAttribute("authCode", strCode.toLowerCase());
        g.dispose();

        ImageIO.write(image, "JPEG", response.getOutputStream());
        response.getOutputStream().flush();
    }

    public  Color getColor(int fc,int bc){
        Random random = new Random();
        if(fc>255)
            fc = 255;
        if(bc>255)
            bc = 255;
        int r = fc + random.nextInt(bc - fc);
        int g = fc + random.nextInt(bc - fc);
        int b = fc + random.nextInt(bc - fc);
        return new Color(r,g,b);
    }

    @RequestMapping(value = "checkCode",method = RequestMethod.POST)
    @ResponseBody
    public String checkAuthCode(@RequestParam(value = "inputCode") String inputCode, HttpServletRequest request){
        String checkCode=(String) request.getSession().getAttribute("authCode");
        //返回1 代表判断通过,0代表失败
        String isCode=checkCode.equals(inputCode)?"1":"0";
        return isCode;
    }
}

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JSP页面验证码实现

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