一.配置kaptcha的jar包

　　

　　pom.xml配置：

<-- 目前只有2.3.2版本-->    
<!-- https://mvnrepository.com/artifact/com.github.penggle/kaptcha -->
        <dependency>
            <groupId>com.github.penggle</groupId>
            <artifactId>kaptcha</artifactId>
            <version>2.3.2</version>
        </dependency>

 二.kaptcha样式配置

　　web.xml:配置kaptcha的servlet及部分样式

    <servlet>
        <servlet-name>Kaptcha</servlet-name>
        <servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>
        <!-- 定义验证码样式 -->
        <!-- 是否有边框 -->
        <init-param>
            <param-name>kaptcha.border</param-name>
            <!-- 没有边框 no -->
            <param-value>no</param-value>
        </init-param>
        <!-- 字体颜色 -->
        <init-param>
            <param-name>kaptcha.textproducer.font.color</param-name>
            <param-value>red</param-value>
        </init-param>
        <!-- 图片宽度 -->
        <init-param>
            <param-name>kaptcha.image.width</param-name>
            <param-value>135</param-value>
        </init-param>
        <!-- 使用哪些字符生成验证码 -->
        <init-param>
            <param-name>kaptcha.textProducer.char.string</param-name>
            <param-value>ACDEFHKPRSTWX345679</param-value>
        </init-param>
        <!-- 图片高度 -->

        <init-param>
            <param-name>kaptcha.image.height</param-name>
            <param-value>50</param-value>
        </init-param>
        <!-- 字体大小 -->
        <init-param>
            <param-name>kaptcha.textproducer.font.size</param-name>
            <param-value>43</param-value>
        </init-param>
        <!-- 干扰线的颜色 -->
        <init-param>
            <param-name>kaptcha.noise.color</param-name>
            <param-value>black</param-value>
        </init-param>
        <!-- 验证码字符个数 -->
        <init-param>
            <param-name>kaptcha.textproducer.char.length</param-name>
            <param-value>4</param-value>
        </init-param>
            <!-- 字体 -->
        <init-param>
            <param-name>kaptcha.textproducer.font.names</param-name>
            <param-value>Aria</param-value>
        </init-param>    
    </servlet>
    <servlet-mapping>
    <servlet-name>Kaptcha</servlet-name>
    <url-pattern>/Kaptcha</url-pattern>
    </servlet-mapping>

 

　　kaptcha详细参数：

三.后端验证

　　从前端接收验证码并验证是否正确：

import javax.servlet.http.HttpServletRequest;

public class CodeUtil {
    public static boolean checkVerifyCode(HttpServletRequest request) {
        String verifyCodeExpected = (String) request.getSession()
                .getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
        String verifyCodeActual = HttpServletRequestUtil.getString(request, "verifyCodeActual");
        if (verifyCodeActual == null || !verifyCodeActual.equals(verifyCodeExpected)) {
            return false;

        }
        return true;
    }
}

 ·　　前端部分js代码：

.....
<!-- 获取输入框验证码-->
var verifyCodeActual=$('#j_captcha').val();
            if(!verifyCodeActual){
                $.toast("请输出验证码");
                return;
            }
<!--通过ajax异步提交-->
            formData.append('verifyCodeActual',verifyCodeActual);
            $ajax({
                url:registerShopUrl,
                type:'POST',
                data:formData,
                contentType:false,
                processData:false,
                cacche:false,
                success:function(data){
                     if(data.success){
                         $.toast("提交成功");
                     }
                     else{
                         $.toast("提交失败:"+data.errMsg);
                     }
                     $('#captcha_img').click();
                }
            })