Jsp网站登录数字+字母验证码实现
image.jsp创建验证码图片、CreateImage.jsp输入验证码界面把值传给验证的页面checkImage.jsp. 我只修改了下if (rand.equalsIgnoreCase(input)) 不然验证的时候区分大小写.总的来说还行很实用! 验证码图片的文件image.jsp <%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" pageEncoding="UTF-8" %> <%!Color getRandColor(int fc, int bc) {//给定范围获得随机颜色 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); }%> <% //设置页面不缓存 response.setHeader("Pragma", "No-cache"); response.setHeader("Cache-Control", "no-cache"); response.setDateHeader("Expires", 0); // 在内存中创建图象 int width = 80, height = 20; BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 获取图形上下文 Graphics g = image.getGraphics(); //生成随机类 Random random = new Random(); // 设定背景色 g.setColor(getRandColor(200, 250)); g.fillRect(0, 0, width, height); //设定字体 g.setFont(new Font("Times New Roman", Font.BOLD, 18)); //画边框 g.setColor(new Color(0, 0, 0)); g.drawRect(0, 0, width - 1, height - 1); // 随机产生155条干扰线,使图象中的认证码不易被其它程序探测到 g.setColor(getRandColor(160, 200)); for (int i = 0; i < 155; i++) { int x = random.nextInt(width); int y = random.nextInt(height); int xl = random.nextInt(12); int yl = random.nextInt(12); g.drawLine(x, y, x + xl, y + yl); } // 取随机产生的认证码(4位数字) String sRand = ""; for (int i = 0; i < 4; i++) { String rand = null; //随机生成数字或者字母 if (random.nextInt(10) > 5) { rand = String.valueOf((char)(random .nextInt(10) + 48)); } else { rand = String.valueOf((char)(random .nextInt(26) + 65)); } sRand += rand; // 将认证码显示到图象中 g.setColor(new Color(random.nextInt(80), random .nextInt(80), random.nextInt(80))); //调用函数出来的颜色相同,可能是因为种子太接近,所以只能直接生成 g.drawString(rand, 15 * i + 10, 16); } // 将认证码存入SESSION session.setAttribute("rand", sRand); // 图象生效 g.dispose(); // 输出图象到页面 ImageIO.write(image, "JPEG", response.getOutputStream()); %> 使用验证码图片的文件CreateImage.jsp <%@ page contentType="text/html;charset=gb2312" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>认证码输入页面</title> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <META HTTP-EQUIV="Pragma" CONTENT="no-cache"> <META HTTP-EQUIV="Cache-Control" CONTENT="no-cache"> <META HTTP-EQUIV="Expires" CONTENT="0"> </head> <body> <form method=post action="checkImage.jsp"> <table> <tr> <td align=left>系统产生的认证码:</td> <td><img id="code" border=0 src="image.jsp"><a href="#" onClick="javascript:var dt=new Date();document.getElementById('code').src='image.jsp?dt='+dt;">看不清验证码请单击这里</a></td> <!--这里的image.jsp?dt='+dt;很重要,如果只是改为image.jsp则不会有图片改变的效果,因为浏览器认为SRC没有改变,所以一定要生成一个随时在改变的dt来实现这一功能--> </tr> <tr> <td align=left>输入上面的认证码:</td> <td><input type=text name=rand maxlength=4 value=""></td> </tr> <tr> <td colspan=2 align=center><input type=submit value="提交检测"></td> </tr> </table> </form> </body> </html> 验证的页面checkImage.jsp <%@ page contentType="text/html; charset=gb2312" language="java" import="java.sql.*" errorPage="" %> <html> <head> <title>认证码验证页面</title> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"> <META HTTP-EQUIV="Pragma" CONTENT="no-cache"> <META HTTP-EQUIV="Cache-Control" CONTENT="no-cache"> <META HTTP-EQUIV="Expires" CONTENT="0"> </head> <body> <% String rand = (String)session.getAttribute("rand"); String input = request.getParameter("rand"); %> 系统产生的认证码为: <%= rand %><br> 您输入的认证码为: <%= input %><br> <br> <% if (rand.equalsIgnoreCase(input)) { %> <font color=green>输入相同,认证成功!</font> <% } else { %> <font color=red>输入不同,认证失败!</font> <% } %> </body> </html>