simplecaptcha验证码

1·导入jar包
2·配置web.xml
 <!-- 验证码 -->
 <servlet>
  <servlet-name>SimpleCaptcha</servlet-name>
  <servlet-class>nl.captcha.servlet.SimpleCaptcha</servlet-class>
 </servlet>

 <servlet>
  <servlet-name>Captcha</servlet-name>
  <servlet-class>nl.captcha.servlet.CaptchaServlet</servlet-class>
  <init-param>
   <param-name>cap.font.color</param-name>
   <param-value>0,0,255</param-value>
  </init-param>
  <init-param>
   <param-name>cap.char.arr</param-name>
   <param-value>1,2,3,4,5,6,7,8,9,0</param-value>
  </init-param>
  <init-param>
   <param-name>cap.border</param-name>
   <param-value>yes</param-value>
  </init-param>
  <init-param>
   <param-name>cap.border.c</param-name>
   <param-value>black</param-value>
  </init-param>
  <init-param>
   <param-name>cap.border.th</param-name>
   <param-value>1</param-value>
  </init-param>
  <init-param>
   <param-name>cap.background.c.to</param-name>
   <param-value>255,255,255</param-value>
  </init-param>
  <init-param>
   <param-name>cap.background.c.from</param-name>
   <param-value>255,255,255</param-value>
  </init-param>
 </servlet>
 <servlet-mapping>
  <servlet-name>Captcha</servlet-name>
  <url-pattern>/Captcha.jpg</url-pattern>
 </servlet-mapping>


3·在jsp和action中判断
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<HTML>
<HEAD>
<META http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<META name="GENERATOR" content="IBM WebSphere Studio">
<TITLE>SimpleCapchaExample.jsp</TITLE>
</HEAD>
<BODY>


<br><br><br><br>

<%

    String c= (String)session.getAttribute(nl.captcha.servlet.Constants.SIMPLE_CAPCHA_SESSION_KEY) ;
    String parm = (String) request.getParameter("captchafield");
   
    out.println(parm + " ? " + c + ":");
   
    if (c != null && parm != null) {
        if (c.equals(parm)) {
            out.println("<b>true</b>");
        }else {
            out.println("<b>false</b>");
        }
    }
   


%>


<br>
Any improvements are welcome at: <a href="mailto:[email protected]?subject=captcha&data=test">[email protected]</a><br>

<br>

<table>
<tr>
    <td><img src="Captcha.jpg">
</td>
<td valign="top">
<form>
<br>sec code:<input type="text" name="captchafield"><br>
<INPUT type="submit" name="submit">
</form>
</td>
</tr>
</table>

 


</BODY>
</HTML>

 

***********************************

已经解决在liunx下显示bug

 

在没有装X11的服务器上会抛出一个HeadlessException错误,很多资料(包括simple captcha的主页)上介绍要加上 -Djava.awt.headless=true 这个启动参数,但是似乎1.5后并没有用。

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