Jsp+servlet 验证码案例

来源：互联网发布：网络查水表是什么意思编辑：程序博客网时间：2024/06/05 18:09

昨晚在csdn看到一位前辈写一个ajax+servlet+jsp验证，顿时心血来潮，在阅读前辈的代码下我亲手体验一下，做了一个验证码生成工具类，以供大家做个参考。

1：添加VeriyCodeUtils类生成验证码图像

package com.servlet;import java.awt.Color;import java.awt.Font;import java.awt.Graphics2D;import java.awt.image.BufferedImage;import java.io.OutputStream;import java.util.Random;import javax.imageio.ImageIO;/** *  * @author hubiao *验证码生成器 * 用到API * BufferedImage 创建一个图像 * Graphics2D  绘制 * fillRect(x,y,width,height);背景 * font()字体 * drawRect();边框 * drawLine();线 * drwaString:图像数据 * ImageIO 生成图像 */public class VeriyCodeUtils {/** * @param output 保存验证图像的流 * @return  验证码 */public static String newVeriyCode(OutputStream output){int width = 90;int height = 40;int codeCount = 5;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' };  //创建图像对象,8位RGBBufferedImage buffered = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);//通过Crapahices来绘制图像到BufferedImage中Graphics2D gra = buffered.createGraphics();//设置图片背景：白色gra.setColor(Color.WHITE);gra.fillRect(0, 0, width, height);//设置字体,字体大小根据图片高度决定gra.setFont(new Font("Fixedsys",Font.PLAIN,height-2));//设置边框：黑色,1cmgra.setColor(Color.BLACK);gra.drawRect(0, 0, width-1, height-1);//生成10条黑色干扰线gra.setColor(Color.BLACK);Random ran = new Random(); for(int i = 0; i < 70;i++){int x = ran.nextInt(255);int y = ran.nextInt(255);int x1 = ran.nextInt(255);int y1 = ran.nextInt(255);gra.drawLine(x, y,x+x1, y+y1);//画直线}//生成验证码StringBuffer sb = new StringBuffer();int r = 0,g = 0,b = 0; for(int i = 0; i < codeCount; i++){String strRand = String.valueOf(codeSequence[ran.nextInt(codeSequence.length)]);//对每位验证码都生成不同的颜色，增加识别系统难度r = ran.nextInt(255);g = ran.nextInt(255);b = ran.nextInt(255);gra.setColor(new Color(r, g, b));gra.drawString(strRand, (i+1)*13, height-4);sb.append(strRand);}try {ImageIO.write(buffered, "jpeg", output);} catch (Exception e) {throw new RuntimeException(e);}return sb.toString();}}

2：servlet使用验证码

protected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {//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");                //生成验证码图像String veriyCode = VeriyCodeUtils.newVeriyCode(resp.getOutputStream());//将验证码保存到session中HttpSession session = req.getSession();session.setAttribute("validateCode", veriyCode);}

3：JSP页面使用验证码

</head>  <script type="text/javascript">function createCode(){ var t = new Date().getTime();//防止页面缓存，使用时间搓var srcImg = document.getElementById("srcImg");srcImg.src="/ImgVeifyWeb/vity.do?"+t; }  </script>  <body>  <h1>${requestScope.code}</h1>  <img id="srcImg" src="<c:url value="/vity.do"></c:url>" />  #这里使用直接让img访问servlet,通过response响应一个图像流  <a href="##" id="codeId" onclick="createCode()">换一张</a>  <form action="<c:url value="/hello.do"></c:url>" method="post">  <input type="text" name="codeVify"/>  <input type="submit" value="提交"/>  </form>  </body>

3：校验验证码

protected void doPost(HttpServletRequest req, HttpServletResponse resp)throws ServletException, IOException {HttpSession session = req.getSession();Object validateCode = session.getAttribute("validateCode");System.out.println(validateCode);String codeVify = req.getParameter("codeVify");if(codeVify==null || codeVify.equals("")){req.setAttribute("code","验证证不能为空");req.getRequestDispatcher("/index.jsp").forward(req, resp);return;}else if(!validateCode.toString().equalsIgnoreCase(codeVify)){req.setAttribute("code","验证证错误");req.getRequestDispatcher("/index.jsp").forward(req, resp);return;}System.out.println("下面开始 做其他业务操作....");}

校验图如下：

3 1