captcha验证码入门



kaptcha是一个简单易用的验证码生成工具，而且支持中文，你还可以配置其很多属性。

用法：

1、首先到http://code.google.com/p/kaptcha/downloads/list把压缩文件下下来，然后把里面的jar文件加到自己的web项目中。

2在web.xml中配置servlet，代码如下：

<servlet>
        <servlet-name>Kaptchaservlet-name>
        <servlet-class>com.google.code.kaptcha.servlet.KaptchaServletservlet-class>
    servlet>

    <servlet-mapping>
        <servlet-name>Kaptchaservlet-name>
        <url-pattern>/kaptchaurl-pattern>
    servlet-mapping>

		Kaptcha
		com.google.code.kaptcha.servlet.KaptchaServlet
	

	
		Kaptcha
		/kaptcha
	

3.页面代码：

<div id="login" class="container" style="">
        <h2>用户登录h2>
        <form action="#" method="post" accept-charset="utf-8"
            class="navbar-form pull-left">
            <img src="kaptcha" /> <br>
            <input type="text" name="kaptcha" value="" /> <br>
            <p><a class="btn btn-primary" id="upload_btn">上传 a>
        form>
    div>

		
用户登录
		

			 

			 

			
上传 
		
	

4.服务器端代码：

String kaptchaExpected = (String)request.getSession() .getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
String kaptchaReceived = request.getParamater("kaptcha");
if (kaptchaReceived == null || !kaptchaReceived.equalsIgnoreCase(kaptchaExpected)){ setError("kaptcha", "Invalid validation code.");}

String kaptchaExpected = (String)request.getSession() .getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY); 
String kaptchaReceived = request.getParamater("kaptcha"); 
if (kaptchaReceived == null || !kaptchaReceived.equalsIgnoreCase(kaptchaExpected)){ setError("kaptcha", "Invalid validation code.");} 

以上就完成了kaptcha的一个简单的使用，你还可以根据自己的需要进行更详细的配置

<servlet-name>Kaptchaservlet-name>
  <servlet-class>com.google.code.kaptcha.servlet.KaptchaServletservlet-class>

  <init-param>
   <param-name>kaptcha.borderparam-name>
   <param-value>yesparam-value>
  init-param>

  <init-param>
   <param-name>kaptcha.border.colorparam-name>
   <param-value>105,179,90param-value>
  init-param>

  <init-param>
   <param-name>kaptcha.textproducer.implparam-name>
   <param-value>org.cric.util.ChineseTextparam-value>
  init-param>

  <init-param>
   <param-name>kaptcha.textproducer.font.colorparam-name>
   <param-value>blackparam-value>
  init-param>

  <init-param>
   <param-name>kaptcha.image.widthparam-name>
   <param-value>130param-value>
  init-param>

  <init-param>
   <param-name>kaptcha.image.heightparam-name>
   <param-value>44param-value>
  init-param>

  <init-param>
   <param-name>kaptcha.textproducer.font.sizeparam-name>
   <param-value>30param-value>
  init-param>

  <init-param>
   <param-name>kaptcha.textproducer.char.lengthparam-name>
   <param-value>4param-value>
  init-param>

  <init-param>
   <param-name>kaptcha.textproducer.font.namesparam-name>
   <param-value>宋体,楷体,微软雅黑param-value>
  init-param>

 servlet>

Kaptcha
  com.google.code.kaptcha.servlet.KaptchaServlet
  
  
   kaptcha.border
   yes
  
  
  
   kaptcha.border.color
   105,179,90
  
  
  
   kaptcha.textproducer.impl
   org.cric.util.ChineseText
  
  
  
   kaptcha.textproducer.font.color
   black
  
  
  
   kaptcha.image.width
   130
  
  
  
   kaptcha.image.height
   44
  
  
  
   kaptcha.textproducer.font.size
   30
  
  
  
   kaptcha.textproducer.char.length
   4
  
  
  
   kaptcha.textproducer.font.names
   宋体,楷体,微软雅黑