java uses kaptcha plugin to generate graphic verification code

Generate graphic captcha using kaptcha plugin

When doing maintenance on a project recently, the customer suggested that the previous verification code was too simple and needed to be replaced with a relatively complex verification code, so this time, kaptcha was used to generate the graphic verification code.

First, download the jar package

If it is a maven project, use maven to download directly,

<dependency>
    <groupId>com.github.penggle</groupId>
    <artifactId>kaptcha</artifactId>
    <version>2.3.2</version>
</dependency>

If it is not managed by maven, download the jar package directly and put it
under
lib

Configure spring beans

Because I use the springmvc architecture, I configure it directly in application.xml,

    <bean id="captchaProducer" class="com.google.code.kaptcha.impl.DefaultKaptcha">
        <property name="config">
            <bean class="com.google.code.kaptcha.util.Config">
                <constructor-arg type="java.util.Properties">
                     <props>
                        <prop key="kaptcha.border">yes</prop>
                        <prop key="kaptcha.border.color">228,228,228</prop>
                        <prop key="kaptcha.border.thickness">1</prop>
                        <prop key="kaptcha.image.width">260</prop>
                        <prop key="kaptcha.image.height">50</prop>
                        <prop key="kaptcha.producer.impl">com.google.code.kaptcha.impl.DefaultKaptcha</prop>
                        <prop key="kaptcha.textproducer.impl">com.google.code.kaptcha.text.impl.DefaultTextCreator</prop>
                        <prop key="kaptcha.textproducer.char.string">abcdefhjkmnopqrstuvwxyz2345678</prop>
                        <prop key="kaptcha.textproducer.char.length">5</prop>
                        <prop key="kaptcha.textproducer.font.names">宋体,楷体,微软雅黑</prop>
                        <prop key="kaptcha.textproducer.font.size">40</prop>
                        <prop key="kaptcha.textproducer.char.space">5</prop>
                        <prop key="kaptcha.session.key">KAPTCHA_SESSION_KEY</prop>
                        <prop key="kaptcha.session.date">KAPTCHA_SESSION_DATE</prop>
                    </props> 
                </constructor-arg>
            </bean>
        </property>
    </bean>

This is a captchaProducer configured, mainly relying on this bean to generate the verification code

Create a tool class KaptchaUtils.java

package com.hzseek.util;

import java.awt.image.BufferedImage;
import javax.servlet.http.HttpSession;
import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.google.code.kaptcha.Producer;

public class KaptchaUtils {

    private static Producer captchaProducer;

    private static Logger logger = LoggerFactory.getLogger(KaptchaUtils.class);

    public void setCaptchaProducer(Producer captchaProducer) {
        KaptchaUtils.captchaProducer = captchaProducer;
    }

    public static BufferedImage getKapthaImage(HttpSession session) {
        String capText = captchaProducer.createText();
        logger.info("getKapthaImage :" + capText);
        session.setAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY, capText);

        return captchaProducer.createImage(capText);
    }

    public static boolean validCode(HttpSession session, String code) {
        if(StringUtils.isEmpty(code))
            return false;
        else
            return code.equals(session.getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY));
    }
}

call in the controller layer

Because I use struts2, the image stream is output directly in the execute method.

package com.hzseek.web.action;

import java.awt.image.BufferedImage;
import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import org.springside.modules.web.struts2.Struts2Utils;
import com.hzseek.util.KaptchaUtils;
import com.opensymphony.xwork2.ActionSupport;

@SuppressWarnings("serial")
public class KaptchaAction extends ActionSupport{

    @Override
    public String execute() throws Exception {
        HttpServletResponse response = Struts2Utils.getResponse();

        response.setHeader("Cache-Control", "no-store");
        response.setHeader("Pragma", "no-cache");
        response.setDateHeader("Expires", 0);
        response.setContentType("image/jpeg");

        //利用生成的字符串构建图片
        BufferedImage image = KaptchaUtils.getKapthaImage(Struts2Utils.getSession());
        ServletOutputStream out = response.getOutputStream();
        ImageIO.write(image, "jpeg", out); 
        try {
            out.flush();
        } catch (Exception e) {
            e.printStackTrace();
        } finally{
            out.close();
        }
        return null;
    }
}

front-end code

call directly through the url

<img id="validCodeImage" src="${request.contextPath}/kaptcha.action"/><a href="javascript:changeValidCode('#validCodeImage');" tabindex="5">看不清，换一张</a>

If you want to click to switch, you can add a js method

function changeValidCode(obj) {
    $(obj).attr('src','${request.contextPath}/kaptcha.action?id=' + Math.random());
}

Effect

The following are the kaptcha graphic verification code configurable items

Constant	describe	Defaults
kaptcha.border	Image border, legal values: yes , no	yes
kaptcha.border.color	Border color, legal values: r,g,b (and optional alpha) or white,black,blue.	black
kaptcha.border.thickness	Border thickness, legal value: >0	1
kaptcha.image.width	picture width	200
kaptcha.image.height	Picture high	50
kaptcha.producer.impl	Image implementation class	com.google.code.kaptcha.impl.DefaultKaptcha
kaptcha.textproducer.impl	Text implementation class	com.google.code.kaptcha.text.impl.DefaultTextCreator
kaptcha.textproducer.char.string	A collection of text from which the captcha value is obtained	abcde2345678gfynmnpwx
kaptcha.textproducer.char.length	verification code length	5
kaptcha.textproducer.font.names	font	Arial, Courier
kaptcha.textproducer.font.size	font size	40px.
kaptcha.textproducer.font.color	Font color, legal values: r,g,b or white,black,blue.	black
kaptcha.textproducer.char.space	text spacing	2
kaptcha.noise.impl	Interference implementation class	com.google.code.kaptcha.impl.DefaultNoise
kaptcha.noise.color	Interference color, legal values: r,g,b or white,black,blue.	black
kaptcha.obscurificator.impl	Image styles: Water Ripple com.google.code.kaptcha.impl.WaterRipple Fisheye com.google.code.kaptcha.impl.FishEyeGimpy Shadow com.google.code.kaptcha.impl.ShadowGimpy	com.google.code.kaptcha.impl.WaterRipple
kaptcha.background.impl	background implementation class	com.google.code.kaptcha.impl.DefaultBackground
kaptcha.background.clear.from	background color gradient, start color	light grey
kaptcha.background.clear.to	background color gradient, end color	white
kaptcha.word.impl	text renderer	com.google.code.kaptcha.text.impl.DefaultWordRenderer
kaptcha.session.key	session key	KAPTCHA_SESSION_KEY
kaptcha.session.date	session date	KAPTCHA_SESSION_DATE

Readers can choose according to their own needs, and they can experiment by themselves, which is quite interesting.