java实现验证码demo

最近要做一个网站，要求实现验证码程序，经过不断调试，终于成功实现功能。

一：验证码生成类

生成验证码的话需要用到java的Graphics类库，画出一个验证码
废话不多说，直接上代码

package verificationCode;


import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.awt.image.RenderedImage;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

import javax.imageio.ImageIO;

public class generateCode {
    private static int width = 150;// 定义图片的width
    private static int height = 48;// 定义图片的height
    private static int codeCount = 4;// 定义图片上显示验证码的个数
    private static int xx = 25;
    private static int fontHeight = 42;
    private static  int codeY = 42;
    private static char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R',
            'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' };

    /**
     * 生成一个map集合
     * code为生成的验证码
     * codePic为生成的验证码BufferedImage对象
     * @return
     */
    public static Map<String,Object> generateCodeAndPic() {
        // 定义图像buffer
        BufferedImage buffImg = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        // Graphics2D gd = buffImg.createGraphics();
        // Graphics2D gd = (Graphics2D) buffImg.getGraphics();
        Graphics gd = buffImg.getGraphics();
        // 创建一个随机数生成器类
        Random random = new Random();
        // 将图像填充为白色
        gd.setColor(Color.WHITE);
        gd.fillRect(0, 0, width, height);

        // 创建字体，字体的大小应该根据图片的高度来定。
        Font font = new Font("Fixedsys", Font.BOLD, fontHeight);
        // 设置字体。
        gd.setFont(font);

        // 画边框。
        gd.setColor(Color.BLACK);
        gd.drawRect(0, 0, width - 1, height - 1);
        gd.setFont(font);
        // 随机产生40条干扰线，使图象中的认证码不易被其它程序探测到。
        int red = 0, green = 0, blue = 0;


        // randomCode用于保存随机产生的验证码，以便用户登录后进行验证。
        StringBuffer randomCode = new StringBuffer();


        // 随机产生codeCount数字的验证码。
        for (int i = 0; i < codeCount; i++) {
            // 得到随机产生的验证码数字。
            String code = String.valueOf(codeSequence[random.nextInt(36)]);
            // 产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。
            red = random.nextInt(255);
            green = random.nextInt(255);
            blue = random.nextInt(255);
            // 用随机产生的颜色将验证码绘制到图像中。
            gd.setColor(new Color(red, green, blue));
            gd.drawString(code, (i + 1) * xx, codeY);

            // 将产生的四个随机数组合在一起。
            randomCode.append(code);
        }
        for (int i = 0; i < 60; i++) {
            red = random.nextInt(255);
            green = random.nextInt(255);
            blue = random.nextInt(255);
            // 用随机产生的颜色将验证码绘制到图像中。
            gd.setColor(new Color(red, green, blue));
            int x = random.nextInt(width);
            int y = random.nextInt(height);
            int xl = random.nextInt(50);
            int yl = random.nextInt(50);
            gd.drawLine(x, y, x + xl, y + yl);
        }
        Map<String,Object> map  =new HashMap<String,Object>();
        //存放验证码
        map.put("code", randomCode);
        //存放生成的验证码BufferedImage对象
        map.put("codePic", buffImg);
        return map;
    }

    public static void main(String[] args) throws Exception {
        //创建文件输出流对象
        File file = new File("WebRoot/image/"+System.currentTimeMillis()+".jpg");
        FileOutputStream out = null;
        try {
            if (!file.exists()) {
                // 先得到文件的上级目录，并创建上级目录，在创建文件
                file.getParentFile().mkdir();
                file.createNewFile();
            }
            out = new FileOutputStream(file);
        Map<String,Object> map = generateCode.generateCodeAndPic();
        ImageIO.write((RenderedImage) map.get("codePic"), "jpeg", out);
        System.out.println("验证码的值为："+map.get("code"));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

二：验证码验证类

package verificationCode;


import java.io.IOException;
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;


@WebServlet("/checkCode")
public class checkCode extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

    }

    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String code = request.getParameter("code");
        response.setCharacterEncoding("utf-8");//保证格式正确
        response.setContentType("text/html");
        // 验证验证码
        String sessionCode = request.getSession().getAttribute("code").toString();
        if (code != null && !"".equals(code) && sessionCode != null && !"".equals(sessionCode)) {
            if (code.equalsIgnoreCase(sessionCode)) {
                response.getWriter().println("验证通过！");
            } else {
                response.getWriter().println("验证失败！");
            }
        } else {
            response.getWriter().println("验证失败！");
        }
    }

}

三：验证码传输类

用到doget方法

package verificationCode;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.awt.image.RenderedImage;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
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 verificationCode.generateCode;
/**
 * Servlet implementation class CodeServlet
 */
@WebServlet("/getCode")
public class CodeServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // 调用工具类生成的验证码和验证码图片
        Map<String, Object> codeMap = generateCode.generateCodeAndPic();

        // 将四位数字的验证码保存到Session中。
        HttpSession session = req.getSession();
        session.setAttribute("code", codeMap.get("code").toString());

        // 禁止图像缓存。
        resp.setHeader("Pragma", "no-cache");
        resp.setHeader("Cache-Control", "no-cache");
        resp.setDateHeader("Expires", 0);

        resp.setContentType("image/jpeg");

        // 将图像输出到Servlet输出流中。
        ServletOutputStream sos;
        try {
            sos = resp.getOutputStream();
            ImageIO.write((RenderedImage) codeMap.get("codePic"), "jpeg", sos);
            sos.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}

四：jsp验证demo

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>验证码页面</title>
<script type="text/javascript"
    src="${pageContext.request.contextPath}/js/jquery.js"></script>
</head>
<body>
    <form action="${pageContext.request.contextPath}/checkCode" method="post">
        请输入验证码：<input type="text" name="code" style="width: 80px;" /> <div id=random> <img id="imgObj" alt="验证码"
            src="${pageContext.request.contextPath}/getCode"> </div><button id="b01" type="button">改变内容</button><br/> <input
            type="submit" value="提交" />
    </form>
</body>
<script type="text/javascript">
    $(function() {
        //response.getWriter().println("验证失败！");
    });

    $("#b01").click( function changeImg() {  


         $("#random").html("<img id='imgObj' alt='验证码' src='${pageContext.request.contextPath}/getCode'>")     
         var imgSrc = $("#imgObj");    
        var src = imgSrc.attr("src");        
        imgSrc.attr("src", chgUrl(src)); 
    });

    // 时间戳
    // 为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳
    function chgUrl(url) {
        var timestamp = (new Date()).valueOf();
        url = url.substring(0, 20);
        if ((url.indexOf("&") >= 0)) {
            url = url + "×tamp=" + timestamp;
        } else {
            url = url + "?timestamp=" + timestamp;
        }
        return url;
    }

</script>
</html>

总结

虽然只是一个小小的demo，但是实际上用到了许多知识，比如生成验证码的画图，传输验证码doget，验证验证码的dopost和ajax动态更换验证码，麻雀虽小五脏俱全啊。

参考网址https://www.cnblogs.com/nanyangke-cjz/p/7049281.html