Spring+JCaptcha验证码使用示例

1，导入jcaptcha.jar包，这里用的是1.0版本

2，编写captcha-context.xml配置文件（非必须，可在spring配置文件中直接添加）：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://www.springframework.org/schema/beans
         http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="captchaService" class="com.octo.captcha.service.multitype.GenericManageableCaptchaService">
        <constructor-arg index="0" ref="imageEngine"/>
        <constructor-arg type="int" index="1" value="180"/>
        <constructor-arg type="int" index="2" value="100000"/>
        <constructor-arg type="int" index="3" value="75000"/>
    </bean>
    <bean id="imageEngine" class="com.octo.captcha.engine.GenericCaptchaEngine">
        <constructor-arg index="0">
            <list>
                <ref bean="captchaFactory"/>
            </list>
        </constructor-arg>
    </bean>

    <bean id="captchaFactory" class="com.octo.captcha.image.gimpy.GimpyFactory">
        <constructor-arg>
            <ref bean="wordgen"/>
        </constructor-arg>
        <constructor-arg>
            <ref bean="wordtoimage"/>
        </constructor-arg>
    </bean>

    <bean id="wordgen" class= "com.octo.captcha.component.word.wordgenerator.RandomWordGenerator">
        <!--可选字符-->
        <constructor-arg>
            <value>0123456789</value>
            <!-- <value>abcdefghijklmnopquvwxyz</value> -->
        </constructor-arg>
    </bean>

    <bean id="wordtoimage" class="com.octo.captcha.component.image.wordtoimage.ComposedWordToImage">
        <constructor-arg index="0">
            <ref bean="fontGenRandom"/>
        </constructor-arg>
        <constructor-arg index="1">
            <ref bean="backGenUni"/>
        </constructor-arg>
        <constructor-arg index="2">
            <ref bean="decoratedPaster"/>
        </constructor-arg>
    </bean>

    <bean id="fontGenRandom" class="com.octo.captcha.component.image.fontgenerator.RandomFontGenerator">
        <!--最小字体-->
        <constructor-arg index="0">
            <value>16</value>
        </constructor-arg>
        <!--最大字体-->
        <constructor-arg index="1">
            <value>20</value>
        </constructor-arg>
        <constructor-arg index="2">
            <list>
                <bean class="java.awt.Font">
                    <constructor-arg index="0"><value>Arial</value></constructor-arg>
                    <constructor-arg index="1"><value>0</value></constructor-arg>
                    <constructor-arg index="2"><value>12</value></constructor-arg>
                </bean>
            </list>
        </constructor-arg>
    </bean>
    <bean id="backGenUni" class="com.octo.captcha.component.image.backgroundgenerator.FunkyBackgroundGenerator">
        <!--背景宽度-->
        <constructor-arg index="0">
            <value>90</value>
        </constructor-arg>
        <!--背景高度-->
        <constructor-arg index="1">
            <value>30</value>
        </constructor-arg>
    </bean>

    <bean id="decoratedPaster" class="com.octo.captcha.component.image.textpaster.DecoratedRandomTextPaster">
        <!--最大字符长度-->
        <constructor-arg type="java.lang.Integer" index="0">
            <value>4</value>
        </constructor-arg>
        <!--最小字符长度-->
        <constructor-arg type="java.lang.Integer" index="1">
            <value>4</value>
        </constructor-arg>
        <!--文本颜色-->
        <constructor-arg index="2">
            <ref bean="colorGen"/>
        </constructor-arg>
        <!--文本混淆-->
        <constructor-arg index="3">
            <list>
                <ref bean="baffleDecorator"/>
            </list>
        </constructor-arg>
    </bean>
    <bean id="baffleDecorator" class="com.octo.captcha.component.image.textpaster.textdecorator.BaffleTextDecorator">
        <constructor-arg type="java.lang.Integer" index="0"><value>1</value></constructor-arg>
        <constructor-arg type="java.awt.Color" index="1"><ref bean="colorWrite"/></constructor-arg>
    </bean>
    <bean id="colorGen" class="com.octo.captcha.component.image.color.SingleColorGenerator">
        <constructor-arg type="java.awt.Color" index="0">
            <ref bean="colorBlack"/>
        </constructor-arg>
    </bean>
    <bean id="colorWrite" class="java.awt.Color">
        <constructor-arg type="int" index="0">
            <value>255</value>
        </constructor-arg>
        <constructor-arg type="int" index="1">
            <value>255</value>
        </constructor-arg>
        <constructor-arg type="int" index="2">
            <value>255</value>
        </constructor-arg>
    </bean>
    <bean id="colorBlack" class="java.awt.Color">
        <constructor-arg type="int" index="0">
            <value>50</value>
        </constructor-arg>
        <constructor-arg type="int" index="1">
            <value>50</value>
        </constructor-arg>
        <constructor-arg type="int" index="2">
            <value>50</value>
        </constructor-arg>
    </bean>
</beans>

3，编写JcaptchaServlet响应请求提供验证码输出:

protected void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, IOException {

        byte[] captchaChallengeAsJpeg = null;
        // 输出jpg的字节流
        ByteArrayOutputStream jpegOutputStream = new ByteArrayOutputStream();
        try {
            // get the session id that will identify the generated captcha.
            // the same id must be used to validate the response, the session id
            // is a good candidate!

            String captchaId = session.getSessionId(request);
            BufferedImage challenge = captchaService.getImageChallengeForID(
                    captchaId, request.getLocale());
            // a jpeg encoder
            JPEGImageEncoder jpegEncoder = JPEGCodec
                    .createJPEGEncoder(jpegOutputStream);
            jpegEncoder.encode(challenge);
        } catch (IllegalArgumentException e) {
            response.sendError(HttpServletResponse.SC_NOT_FOUND);
            return;
        } catch (CaptchaServiceException e) {
            response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            return;
        }

        captchaChallengeAsJpeg = jpegOutputStream.toByteArray();

        // flush it in the response
        response.setHeader("Cache-Control", "no-store");
        response.setHeader("Pragma", "no-cache");
        response.setDateHeader("Expires", 0);
        response.setContentType("image/" + CAPTCHA_IMAGE_FORMAT);

        ServletOutputStream responseOutputStream = response.getOutputStream();
        responseOutputStream.write(captchaChallengeAsJpeg);
        responseOutputStream.flush();
        responseOutputStream.close();
    }

4，在web.xml中添加该servlet：

<!-- Jcaptcha -->
    <servlet>
        <servlet-name>Jcaptcha</servlet-name>
        <servlet-class>cn.xxx.JcaptchaServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>Jcaptcha</servlet-name>
        <url-pattern>/captcha.jpg</url-pattern>
    </servlet-mapping>

5，在html中显示验证码只需要以下代码：

<div><img src="${base }/captcha.jpg" onclick="this.src='${base}/captcha.jpg?'+Math.random()"/></div>
<div class="input_capt">验证码: <input type="text"id="captcha" name="captcha" />

6，后台验证的话，只需要调用ImageCaptchaService的一个方法即可：

imageCaptchaService.validateResponseForID(session.getSessionId(getRequest()), captcha);