[Java]Spring/SpringBoot实现验证码（Kaptcha的多种自定义使用）

前言

Kaptcha是我项目中在用的一个验证码产生工具，产生的验证码比较漂亮且可定制程度比较高，所以很好用。

可配置的项目如下：

• 字体
• 字体的大小
• 字体颜色
• 验证码内容的范围(数字，字母，中文汉字！)
• 验证码图片的大小，边框，边框粗细，边框颜色
• 验证码的干扰线
• 验证码的样式(鱼眼样式、3D、普通模糊...)

生成的验证码示例：

使用

如果是Maven，加入pom.xml:

<dependency>
      <groupId>com.google.code.kaptcha</groupId> 
      <artifactId>kaptcha</artifactId> 
      <version>2.3</version>
 </dependency>

如果是Gradle，加入build.gradle

implementation("com.google.code.kaptcha:kaptcha:2.3")

新建KaptchaController.java

生成的captcha验证码的文本，存在session的com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY里面，下一次用户提交验证码，只要从session里取出key：com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY，和用户输入的对比就可以了

package com.terrynow.test.controller;

import com.google.code.kaptcha.Producer;
import com.google.code.kaptcha.servlet.KaptchaExtend;
import com.google.code.kaptcha.util.Config;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import javax.imageio.ImageIO;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Properties;

import static com.google.code.kaptcha.Constants.*;

/**
 * @description These values are stored in the com.google.code.kaptcha.Constants class.
 * <p>
 * Constant	Description	Default
 * kaptcha.border	Border around kaptcha. Legal values are yes or no.	yes
 * kaptcha.border.color	Color of the border. Legal values are r,g,b (and optional alpha) or white,black,blue.	black
 * kaptcha.border.thickness	Thickness of the border around kaptcha. Legal values are > 0.	1
 * kaptcha.image.width	Width in pixels of the kaptcha image.	200
 * kaptcha.image.height	Height in pixels of the kaptcha image.	50
 * kaptcha.producer.impl	The image producer.	com.google.code.kaptcha.impl.DefaultKaptcha
 * kaptcha.textproducer.impl	The text producer.	com.google.code.kaptcha.text.impl.DefaultTextCreator
 * kaptcha.textproducer.char.string	The characters that will create the kaptcha.	abcde2345678gfynmnpwx
 * kaptcha.textproducer.char.length	The number of characters to display.	5
 * kaptcha.textproducer.font.names	A list of comma separated font names.	Arial, Courier
 * kaptcha.textproducer.font.size	The size of the font to use.	40px.
 * kaptcha.textproducer.font.color	The color to use for the font. Legal values are r,g,b.	black
 * kaptcha.textproducer.char.space	The space between the characters	2
 * kaptcha.noise.impl	The noise producer.	com.google.code.kaptcha.impl.DefaultNoise
 * kaptcha.noise.color	The noise color. Legal values are r,g,b.	black
 * kaptcha.obscurificator.impl	The obscurificator implementation.	com.google.code.kaptcha.impl.WaterRipple
 * kaptcha.background.impl	The background implementation.	com.google.code.kaptcha.impl.DefaultBackground
 * kaptcha.background.clear.from	Starting background color. Legal values are r,g,b.	light grey
 * kaptcha.background.clear.to	Ending background color. Legal values are r,g,b.	white
 * kaptcha.word.impl	The word renderer implementation.	com.google.code.kaptcha.text.impl.DefaultWordRenderer
 * kaptcha.session.key	The value for the kaptcha is generated and is put into the HttpSession. This is the key value for that item in the session.	KAPTCHA_SESSION_KEY
 * kaptcha.session.date	The date the kaptcha is generated is put into the HttpSession. This is the key value for that item in the session.	KAPTCHA_SESSION_DATE
 */
@Controller
public class KaptchaController extends KaptchaExtend {

    //--kaptcha验证码设置参数
    private Properties props = new Properties();
    private Producer kaptchaProducer = null;

    public KaptchaController() {
        ImageIO.setUseCache(false);

        this.props.put(KAPTCHA_TEXTPRODUCER_CHAR_LENGTH, "4");
        this.props.put(KAPTCHA_TEXTPRODUCER_CHAR_STRING, "1234567890");
        this.props.put(KAPTCHA_BORDER, "no");
        this.props.put(KAPTCHA_IMAGE_WIDTH, "300");
        this.props.put(KAPTCHA_IMAGE_HEIGHT, "100");
        this.props.put(KAPTCHA_TEXTPRODUCER_FONT_SIZE, "80");


        Config config1 = new Config(this.props);
        this.kaptchaProducer = config1.getProducerImpl();
    }

    @RequestMapping({"/captcha.jpg", "**/captcha.jpg"})
    public void captcha(HttpServletResponse response, HttpSession session) throws IOException {
        // flush it in the response
        response.setHeader("Cache-Control", "no-store");
        response.setHeader("Pragma", "no-cache");
        response.setDateHeader("Expires", 0);
        response.setContentType("image/jpeg");

        String capText = this.kaptchaProducer.createText();
        BufferedImage bi = this.kaptchaProducer.createImage(capText);
        ServletOutputStream responseOutputStream = response.getOutputStream();
        // 本次产生的验证码文本存在session里，下次用户提交的时候，从session里取出后，和用户输入的对比来判断验证码是否正确
        session.setAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY, capText);
        ImageIO.write(bi, "jpeg", responseOutputStream);
        // 以下关闭输入流！
        responseOutputStream.flush();
        responseOutputStream.close();
    }

}

上面代码里有英文关于验证码操作的介绍，这边翻译下整理如下：

com.google.code.kaptcha.Constants的参数如下

网页上输出并更换验证码，简单示例不多做介绍：

<img id="captcha" src="/captcha" style="cursor: pointer;" title="点击换一张" />

$(function () { // 刷新验证码，这个根据所使用的JS框架自由实现
    $("#captcha").click(function () { 
        $(this).hide().attr('src', '/captcha?r=' + Math.random()).fadeIn(); 
    });
});