JAVA验证码的实现参考

java验证码的实现(一)?
1.ImageServlet类的实现：
package com.mobile.control;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
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;
public class ImageServlet extends HttpServlet {
?????? public void doGet(HttpServletRequest request, HttpServletResponse response)
???????????????????? throws ServletException, IOException {
????????????? this.doPost(request, response);
?????? }
?????? // 生成数字和字母的验证码
?????? public void doPost(HttpServletRequest request, HttpServletResponse response)
???????????????????? throws ServletException, IOException {
????????????? BufferedImage img = new BufferedImage(68, 22,
??????????????????????????? BufferedImage.TYPE_INT_RGB);
????????????? // 得到该图片的绘图对象
????????????? Graphics g = img.getGraphics();
????????????? Random r = new Random();
????????????? Color c = new Color(200, 150, 255);
????????????? g.setColor(c);
????????????? // 填充整个图片的颜色
????????????? g.fillRect(0, 0, 68, 22);
????????????? // 向图片中输出数字和字母
????????????? StringBuffer sb = new StringBuffer();
????????????? char[] ch = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();
????????????? int index, len = ch.length;
????????????? for (int i = 0; i < 4; i ++) {
???????????????????? index = r.nextInt(len);
???????????????????? g.setColor(new Color(r.nextInt(88), r.nextInt(188), r.nextInt
(255)));
???????????????????? g.setFont(new Font("Arial", Font.BOLD | Font.ITALIC, 22));// 输出的
字体和大小?????????????????
???????????????????? g.drawString("" + ch[index], (i * 15) + 3, 18);//写什么数字，在图片
的什么位置画
???????????????????? sb.append(ch[index]);
????????????? }
????????????? request.getSession().setAttribute("piccode", sb.toString());
????????????? ImageIO.write(img, "JPG", response.getOutputStream());
?????? }????
}
2.web.xml中的配置
?????? <servlet>
????????????? <servlet-name>ImageServlet</servlet-name>
????????????? <servlet-class>com.mobile.control.ImageServlet</servlet-class>
?????? </servlet>
?????? <servlet-mapping>
????????????? <servlet-name>ImageServlet</servlet-name>
????????????? <url-pattern>/servlet/ImageServlet</url-pattern>
?????? </servlet-mapping>
3.页面源程序
<%@ page contentType="text/html; charset=utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
?????? <head>
????????????? <title>系统登录</title>
????????????? <meta http-equiv="pragma" content="no-cache">
????????????? <meta http-equiv="cache-control" content="no-cache">
????????????? <meta http-equiv="expires" content="0">
????????????? <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
????????????? <meta http-equiv="description" content="This is my page">????????????
?
????????????? <link href="<%=request.getContextPath()%>/jsp/style/stylet.css"
???????????????????? rel="stylesheet" type="text/css">??
????????????? <mce:script type="text/javascript"></mce:script>
?????? </head>
?
?????? <body>
????????????? <div id="box1">
???????????????????? <div id="tab_box">
??????????????????????????? <form action="<%=request.getContextPath() %
>/servlet/LoginServlet" method="post" name="login">
?????????????????????????????????? <span type="text" id="userid"
accesskey="n"
????????????????????????????????????????? tabindex="1"
????????????????????????????????????????? style="font-family: '宋体'; font-size: 12px;
color: #575757" />
?????????????????????????????????? <br />
?????????????????????????????????? <br />
?????????????????????????????????? <label for="passwd" type="password" id="passwd"
tabindex="2"
????????????????????????????????????????? style="font-family: '宋体'; font-size: 12px;
color: #575757" />
?????????????????????????????????? <br />
?????????????????????????????????? <br />??????????????????????????????????????????????
?????????????????????????????????? <label for="verifyCode" id="verifyCode" name="verifyCode"
size="6" />
?????????????????????????????????? <img alt="JAVA验证码的兑现参考" id="safecode" src="<%
=request.getContextPath()%>/servlet/ImageServlet">
?????????????????????????????????? <a href="javascript:reloadVerifyCode();"
mce_href="javascript:reloadVerifyCode();">看不清楚</a>
?????????????????????????????????? <input name="denglu_tijiao" type="submit"
id="denglu_tijiao"
????????????????????????????????????????? tabindex="3" value="确认" />
?????????????????????????????????? <input name="denglu_chongzi" type="reset"
id="denglu_reset"
????????????????????????????????????????? tabindex="4" value="重置" />
?????????????????????????????????? <input type="hidden" name="flag" value="logon">
??????????????????????????? </form>
??????????????????????????? <font color='red'></font>
???????????????????? </div>
????????????? </div>
?????? </body>
</html>