Java实现验证码制作之一Kaptcha验证码

Kaptcha验证码是google提供的验证码插件，使用起来相对简单，设置的干扰线以及字体扭曲不易让其他人读取破解。

这里我们需要导入一个 kaptcha-2.3.jar
下载地址：http://pan.baidu.com/s/1dDzw7Bj

jar包中有个 KaptchaServlet 的servlet,每次访问都会保存在session 作用域当中

默认保存的名称是 KAPTCHA_SESSION_KEY 你也可以自己设定保存过名称

看xml中的注释的 “session中存放验证码的key键” 配置,同时你也可以根据个人的需求去设置其他验证码的参数属性

//web.xml 配置

<servlet>
<servlet-name>kaptcha</servlet-name>
<servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>

<!– <init-param>
           <description>图片边框，合法值：yes , no</description>
           <param-name>kaptcha.border</param-name>
           <param-value>yes</param-value>
       </init-param>
       <init-param>
           <description>
               边框颜色，合法值： r,g,b (and optional alpha) 或者
               white,black,blue.
           </description>
           <param-name>kaptcha.border.color</param-name>
           <param-value>black</param-value>
       </init-param>
       <init-param>
           <description>边框厚度，合法值：>0</description>
           <param-name>kaptcha.border.thickness</param-name>
           <param-value>1</param-value>
       </init-param>
       <init-param>
           <description>图片宽 200</description>
           <param-name>kaptcha.image.width</param-name>
           <param-value>200</param-value>
       </init-param>
       <init-param>
           <description>图片高 50</description>
           <param-name>kaptcha.image.height</param-name>
           <param-value>50</param-value>
       </init-param>
       <init-param>
           <description>图片实现类</description>
           <param-name>kaptcha.producer.impl</param-name>
           <param-value>
               com.google.code.kaptcha.impl.DefaultKaptcha
           </param-value>
       </init-param>
       <init-param>
           <description>文本实现类</description>
           <param-name>kaptcha.textproducer.impl</param-name>
          <param-value>
               com.google.code.kaptcha.text.impl.DefaultTextCreator
           </param-value>
       </init-param>
       <init-param>
           <description>文本集合，验证码值从此集合中获取</description>
           <param-name>kaptcha.textproducer.char.string</param-name>
           <param-value>QWERTYUIOPASDFGHJKLZXCVBNM1234567890</param-value>
       </init-param>
       <init-param>
           <description>验证码长度 5</description>
           <param-name>kaptcha.textproducer.char.length</param-name>
           <param-value>5</param-value>
       </init-param>
       <init-param>
           <description>字体 Arial, Courier</description>
           <param-name>kaptcha.textproducer.font.names</param-name>
           <param-value>Arial, Courier</param-value>
       </init-param>
       <init-param>
           <description>字体大小 40px.</description>
           <param-name>kaptcha.textproducer.font.size</param-name>
           <param-value>40</param-value>
       </init-param>
       <init-param>
           <description>
               字体颜色，合法值： r,g,b 或者 white,black,blue.
           </description>
           <param-name>kaptcha.textproducer.font.color</param-name>
           <param-value>black</param-value>
       </init-param>
       <init-param>
           <description>文字间隔 2</description>
           <param-name>kaptcha.textproducer.char.space</param-name>
           <param-value>2</param-value>
       </init-param>
       <init-param>
           <description>干扰实现类</description>
           <param-name>kaptcha.noise.impl</param-name>
           <param-value>
               <!– com.google.code.kaptcha.impl.NoNoise –>
               com.google.code.kaptcha.impl.DefaultNoise
           </param-value>
       </init-param>
       <init-param>
           <description>
               干扰颜色，合法值： r,g,b 或者 white,black,blue.
           </description>
           <param-name>kaptcha.noise.color</param-name>
           <param-value>black</param-value>
       </init-param>
       <init-param>
           <description>
               图片样式：水纹com.google.code.kaptcha.impl.WaterRipple
               鱼眼com.google.code.kaptcha.impl.FishEyeGimpy
               阴影com.google.code.kaptcha.impl.ShadowGimpy
           </description>
           <param-name>kaptcha.obscurificator.impl</param-name>
           <param-value>
               com.google.code.kaptcha.impl.WaterRipple
           </param-value>
       </init-param>
       <init-param>
           <description>背景实现类</description>
           <param-name>kaptcha.background.impl</param-name>
           <param-value>
               com.google.code.kaptcha.impl.DefaultBackground
           </param-value>
       </init-param>
       <init-param>
           <description>背景颜色渐变，开始颜色</description>
           <param-name>kaptcha.background.clear.from</param-name>
           <param-value>green</param-value>
       </init-param>
       <init-param>
           <description>背景颜色渐变，结束颜色</description>
           <param-name>kaptcha.background.clear.to</param-name>
           <param-value>white</param-value>
       </init-param>
       <init-param>
           <description>文字渲染器</description>
           <param-name>kaptcha.word.impl</param-name>
           <param-value>
               com.google.code.kaptcha.text.impl.DefaultWordRenderer
           </param-value>
       </init-param>
       <init-param>
           <description>
               session中存放验证码的key键
           </description>
           <param-name>kaptcha.session.key</param-name>
           <param-value>KAPTCHA_SESSION_KEY</param-value>
       </init-param>
       <init-param>
           <description>
               The date the kaptcha is generated is put into the
               HttpSession. This is the key value for that item in the
               session.
           </description>
           <param-name>kaptcha.session.date</param-name>
           <param-value>KAPTCHA_SESSION_DATE</param-value>
       </init-param>–>
</servlet>

<servlet-mapping>
<servlet-name>kaptcha</servlet-name>
<url-pattern>/randomcode.jpg</url-pattern>
</servlet-mapping>

<servlet>
   <servlet-name>loginServlet</servlet-name>
   <servlet-class>com.test.servlet.LoginServlet</servlet-class>
</servlet>
<servlet-mapping>
     <servlet-name>loginServlet</servlet-name>
     <url-pattern>/login.do</url-pattern>
</servlet-mapping>

<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>

//index.jsp 代码

<form action=”<%=request.getContextPath()%>/login.do” method=”get” >
<center>
   <div>
           验证码：<input type=”text” name=”code2″ />
<img alt=”验证码” src=”<%=request.getContextPath()%>/randomcode.jpg” id=”code2″ onclick=”relodCode(this,’randomcode.jpg’)”/>
</div>
<input type=”submit” value=”提交”/>
</center>
</form>
<script type=”text/javascript”>
    function relodCode(obj,url){
       var time=new Date();
       obj.src=”<%=request.getContextPath()%>/”+url+”?time=”+time;
    }
</script>

//提交验证 servlet

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class LoginServlet extends HttpServlet {
   @Override
   protected void doGet(HttpServletRequest req, HttpServletResponse resp)
           throws ServletException, IOException {

       //获取 kaptchaServlet 保存生成的验证码
       String code=(String)req.getSession().getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);

       String code2=req.getParameter(“code2”);
       System.out.println(“code=”+code);
        System.out.println();
       PrintWriter out=null;
       String msg=”输入有误!”;
       try {
           resp.setContentType(“text/html;charset=utf-8”);
           out=resp.getWriter();
           if(code2.equals(code)){
               msg=”输入正确!”;
           }
           out.print(msg+”\tcode=”+code+”\tcode2=”+code2);
       } catch (Exception e) {
           e.printStackTrace();
       }finally{
           if(null!=out) out.close();
       }
       super.doGet(req, resp);
   }

   @Override
   protected void doPost(HttpServletRequest req, HttpServletResponse resp)
           throws ServletException, IOException {
       doGet(req, resp);
   }
}

//效果图(点击验证码刷新)

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