kaptcha生成验证码例子
下载地址：
http://code.google.com/p/kaptcha/
生成图片 jsp页面
<%@page import="javax.imageio.ImageIO"%>
<%@page import="java.awt.image.BufferedImage"%>
<%@page import="com.yongmail.web.ImageCode"%>
<%@page import="com.yongmail.utils.ToolUtil"%>
<%
String sid = request.getParameter("sid");
if (ToolUtil.isEmpty(sid))
return;
out.clear();
response.setDateHeader("Expires", 0);
// Set standard HTTP/1.1 no-cache headers.
response.setHeader("Cache-Control",
"no-store, no-cache, must-revalidate");
// Set IE extended HTTP/1.1 no-cache headers (use addHeader).
response.addHeader("Cache-Control", "post-check=0, pre-check=0");
// Set standard HTTP/1.0 no-cache header.
response.setHeader("Pragma", "no-cache");
// return a jpeg
response.setContentType("image/jpeg");
// create the text for the image
String capText = ImageCode.getProducer().createText();
// store the text in the session
request.getSession().setAttribute(sid, capText);
// create the image with the text
BufferedImage bi = ImageCode.getProducer().createImage(capText);
ServletOutputStream outStr = response.getOutputStream();
// write the data out
ImageIO.write(bi, "jpg", outStr);
try {
outStr.flush();
} finally {
outStr.close();
}
%>
显示页面
<%@ page contentType="text/html; charset=utf-8" language="java" import="java.sql.*" errorPage="" %>
<%@page import="com.yongmail.utils.TimeUtil"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>申请账号</title>
</head>
<%
String id = request.getSession().getId();
String countId = TimeUtil.genId();
%>
<body>
<form action="submitApply.jsp?countId=<%=countId %>" method="post">
<input name="" type="text" />
<input type="submit" name="Submit" value="提交" />
</form>
<% out.print("<img src=\"getCode.jsp?sid="+id+"_"+countId+"\"/>"); %>
</body>
</html>
提交后取得验证码示例
<%@ page contentType="text/html; charset=utf-8" language="java" errorPage="" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>注册</title>
</head>
<body>
<%
String countId = request.getParameter("countId");
System.out.println((String)request.getSession().getAttribute(request.getSession().getId()+"_"+countId));
%>
</body>
</html>
ImageCode类
import java.util.Properties;
import com.google.code.kaptcha.Producer;
import com.google.code.kaptcha.util.Config;
public class ImageCode {
private static Producer kaptchaProducer = null;
private static Properties props = new Properties();
private static Config config = new Config(props);
public static Producer getProducer(){
if(kaptchaProducer == null){
kaptchaProducer = (Producer) config.getProducerImpl();
}
return kaptchaProducer;
}
}