Java如何實(shí)現(xiàn)kaptcha網(wǎng)頁(yè)驗(yàn)證碼驗(yàn)證

更新時(shí)間：2025年01月06日 11:17:24 作者：一個(gè)愛(ài)運(yùn)動(dòng)的程序員

在做關(guān)于SSM項(xiàng)目之商鋪系統(tǒng)時(shí),了解到了kaptcha實(shí)現(xiàn)網(wǎng)頁(yè)驗(yàn)證碼驗(yàn)證,感覺(jué)就很有趣,所以便開(kāi)始學(xué)習(xí)記錄了起來(lái),復(fù)制粘貼即可用

Java實(shí)現(xiàn)kaptcha網(wǎng)頁(yè)驗(yàn)證碼驗(yàn)證

首先來(lái)了解一下什么是驗(yàn)證碼：

驗(yàn)證碼（CAPTCHA) ∶是一種區(qū)分用戶(hù)是計(jì)算機(jī)還是人的公共全自動(dòng)程序。
作用∶可以防止惡意破解密碼、刷票、論壇灌水，有效防止某個(gè)黑客對(duì)某一個(gè)特定注冊(cè)用戶(hù)用特定程序暴力破解方式進(jìn)行不斷的登陸嘗試。實(shí)際上用驗(yàn)證碼是現(xiàn)在很多網(wǎng)站通行的方式（比如招商銀行的網(wǎng)上個(gè)人銀行，百度社區(qū)），我們利用比較簡(jiǎn)易的方式實(shí)現(xiàn)了這個(gè)功能。

下面便一起來(lái)了解kaptcha吧

首先要了解什么是kaptcha？

它一個(gè)java開(kāi)源的驗(yàn)證碼工具包，kaptcha 是一個(gè)非常實(shí)用的驗(yàn)證碼生成工具，可以通過(guò)配置生成多樣化的驗(yàn)證碼。
當(dāng)然除了kaptcha可以實(shí)現(xiàn)驗(yàn)證碼外，還可以通過(guò)servlet、jcaptcha來(lái)實(shí)現(xiàn)驗(yàn)證碼。

kaptcha工作的原理：

調(diào)用 com.google.code.kaptcha.servlet.KaptchaServlet，生成一個(gè)圖片。
同時(shí)將生成的驗(yàn)證碼字符串放到 HttpSession中。

相關(guān)文章：

SpringBoot整合kaptcha驗(yàn)證碼，復(fù)制粘貼即可用

我的項(xiàng)目目錄：

一、引入Maven依賴(lài)

pom.xml:

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

二、編寫(xiě)Servlet

kaptcha可配置項(xiàng)參考：

kaptcha.border --------------------------------------------------是否有邊框默認(rèn)為true 我們可以自己設(shè)置yes，no
kaptcha.border.color -------------------------------------------邊框顏色默認(rèn)為Color.BLACK
kaptcha.border.thickness -------------------------------------邊框粗細(xì)度默認(rèn)為1
kaptcha.producer.impl -----------------------------------------驗(yàn)證碼生成器默認(rèn)為DefaultKaptcha
kaptcha.textproducer.impl ------------------------------------驗(yàn)證碼文本生成器默認(rèn)為DefaultTextCreator
kaptcha.textproducer.char.string ----------------------------驗(yàn)證碼文本字符內(nèi)容范圍默認(rèn)為abcde2345678gfynmnpwx
kaptcha.textproducer.char.length ---------------------------驗(yàn)證碼文本字符長(zhǎng)度默認(rèn)為5
kaptcha.textproducer.font.names ---------------------------驗(yàn)證碼文本字體樣式默認(rèn)為new Font(“Arial”, 1, fontSize), new Font(“Courier”, 1, fontSize)
kaptcha.textproducer.font.size ------------------------------驗(yàn)證碼文本字符大小默認(rèn)為40
kaptcha.textproducer.font.color -----------------------------驗(yàn)證碼文本字符顏色默認(rèn)為Color.BLACK
kaptcha.textproducer.char.space -------------------------- 驗(yàn)證碼文本字符間距默認(rèn)為2
kaptcha.noise.impl ----------------------------------------------驗(yàn)證碼噪點(diǎn)生成對(duì)象默認(rèn)為DefaultNoise
kaptcha.noise.color ---------------------------------------------驗(yàn)證碼噪點(diǎn)顏色默認(rèn)為Color.BLACK
kaptcha.obscurificator.impl ------------------------------------驗(yàn)證碼樣式引擎默認(rèn)為WaterRipple
kaptcha.word.impl -----------------------------------------------驗(yàn)證碼文本字符渲染默認(rèn)為DefaultWordRenderer
kaptcha.background.impl --------------------------------------驗(yàn)證碼背景生成器默認(rèn)為DefaultBackground
kaptcha.background.clear.from ------------------------------驗(yàn)證碼背景顏色漸進(jìn) 默認(rèn)為Color.LIGHT_GRAY
kaptcha.background.clear.to ----------------------------------驗(yàn)證碼背景顏色漸進(jìn) 默認(rèn)為Color.WHITE
kaptcha.image.width --------------------------------------------驗(yàn)證碼圖片寬度默認(rèn)為200
kaptcha.image.height -------------------------------------------驗(yàn)證碼圖片高度默認(rèn)為50

在web.xml文件中配置kaptcha與它的servlet映射等。

web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<!-- 登陸驗(yàn)證碼Kaptcha 2-->
<servlet>
	<servlet-name>Kaptcha</servlet-name>
	<servlet-class>
		com.google.code.kaptcha.servlet.KaptchaServlet
	</servlet-class>
	<init-param>
		<description>圖片邊框，合法值：yes , no</description>
		<param-name>kaptcha.border</param-name>
		<param-value>yes</param-value>
	</init-param>
	<init-param>
		<description>
			邊框顏色，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>邊框厚度，合法值：>0</description>
		<param-name>kaptcha.border.thickness</param-name>
		<param-value>1</param-value>
	</init-param>
	<init-param>
		<description>圖片寬 200</description>
		<param-name>kaptcha.image.width</param-name>
		<param-value>200</param-value>
	</init-param>
	<init-param>
		<description>圖片高 50</description>
		<param-name>kaptcha.image.height</param-name>
		<param-value>50</param-value>
	</init-param>
	<init-param>
		<description>圖片實(shí)現(xiàn)類(lèi)</description>
		<param-name>kaptcha.producer.impl</param-name>
		<param-value>
			com.google.code.kaptcha.impl.DefaultKaptcha
		</param-value>
	</init-param>
	<init-param>
		<description>文本實(shí)現(xiàn)類(lèi)</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，驗(yàn)證碼值從此集合中獲取</description>
		<param-name>kaptcha.textproducer.char.string</param-name>
		<param-value>1234567890</param-value>
		  <!--<param-value>abcde2345678gfynmnpwx</param-value>-->
	</init-param>
	<init-param>
		<description>驗(yàn)證碼長(zhǎng)度 5</description>
		<param-name>kaptcha.textproducer.char.length</param-name>
		<param-value>5</param-value>
	</init-param>
	<init-param>
		<description>字體 Arial, Courier</description>
		<param-name>kaptcha.textproducer.font.names</param-name>
		<param-value>Arial, Courier</param-value>
	</init-param>
	<init-param>
		<description>字體大小 40px.</description>
		<param-name>kaptcha.textproducer.font.size</param-name>
		<param-value>40</param-value>
	</init-param>
	<init-param>
		<description>
			字體顏色，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>文字間隔 2</description>
		<param-name>kaptcha.textproducer.char.space</param-name>
		<param-value>2</param-value>
	</init-param>
	<init-param>
		<description>干擾實(shí)現(xiàn)類(lèi)</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>
			干擾顏色，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>
			圖片樣式： 水紋com.google.code.kaptcha.impl.WaterRipple
			魚(yú)眼com.google.code.kaptcha.impl.FishEyeGimpy
			陰影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>背景實(shí)現(xiàn)類(lèi)</description>
		<param-name>kaptcha.background.impl</param-name>
		<param-value>
			com.google.code.kaptcha.impl.DefaultBackground
		</param-value>
	</init-param>
	<init-param>
		<description>背景顏色漸變，開(kāi)始顏色</description>
		<param-name>kaptcha.background.clear.from</param-name>
		<param-value> black</param-value>
	</init-param>
	<init-param>
		<description>背景顏色漸變，結(jié)束顏色</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中存放驗(yàn)證碼的key鍵
		</description>
		<param-name>kaptcha.session.key</param-name>
		<param-value>KAPTCHA_SESSION_KEY</param-value>
	</init-param>
	<init-param>
		<description>
			生成kaptcha的日期被放入HttpSession中。這是會(huì)話(huà)中該項(xiàng)的鍵值。
		</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>


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

三、編寫(xiě)：頁(yè)面、判斷與跳轉(zhuǎn)

1、只有數(shù)字的驗(yàn)證碼

index.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>randomcode</title>
<script type="text/javascript">
	function changeR(node){
		// 用于點(diǎn)擊時(shí)產(chǎn)生不同的驗(yàn)證碼
		node.src = "randomcode.jpg?time="+new Date().getTime() ;	
	}
</script>
</head>
<body>
<img alt="random" src="randomcode.jpg" onclick="changeR(this)" style="cursor: pointer;">
	<form action="check.jsp">
		<input type="text" name="r">
		<input type="submit" value="確認(rèn)">
	</form>	
</body>
</html>

check.jsp:

<%@ page language="java" contentType="text/html; charset=UTF-8"
	pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>check</title>
</head>
<body>
	<%
		// 檢查是否是正確的驗(yàn)證碼
		String k = (String) session
				.getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
		String str = request.getParameter("r");
		str = new String(str.getBytes("iso-8859-1"),"utf-8");
		if (k.equals(str))
			out.print("輸入驗(yàn)證碼正確！");
		else
			out.print("輸入驗(yàn)證碼錯(cuò)誤?。?！");
		out.print("驗(yàn)證碼為：" + k + ",你輸入的驗(yàn)證碼為：" + str);
	%>
</body>
</html>

結(jié)果為：

2、含義數(shù)字、字母、中文的驗(yàn)證碼

以上便是數(shù)字驗(yàn)證碼，那如果加字母和中文呢？？？

更改web.xml的文本實(shí)現(xiàn)類(lèi)，導(dǎo)入自己創(chuàng)建的類(lèi)：

我的web.xml的引入和我類(lèi)的位置：(自行尋找到進(jìn)行更換)

<init-param>
			<description>文本實(shí)現(xiàn)類(lèi)</description>
			<param-name>kaptcha.textproducer.impl</param-name>
			<param-value>
				com.kaptcha.ChineseText
			</param-value>
		</init-param>

ChineseText.java:

package com.kaptcha;

import java.util.Random;

import com.google.code.kaptcha.text.TextProducer;
import com.google.code.kaptcha.util.Configurable;

public class ChineseText extends Configurable implements TextProducer {
	public String getText() {
		int length = getConfig().getTextProducerCharLength();
		String finalWord = "", firstWord = "";
		int tempInt = 0;
		String[] array = { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9",
				"a", "b", "c", "d", "e", "f","g", "h", "i", "j", "k"};

		Random rand = new Random();

		for (int i = 0; i < length; i++) {
			switch (rand.nextInt(array.length)) {
			case 1:
				tempInt = rand.nextInt(26) + 65;
				firstWord = String.valueOf((char) tempInt);
				break;
			case 2:
				int r1,
				r2,
				r3,
				r4;
				String strH,
				strL;			// high&low
				r1 = rand.nextInt(3) + 11;
				if (r1 == 13) {
					r2 = rand.nextInt(7);
				} else {
					r2 = rand.nextInt(16);
				}

				r3 = rand.nextInt(6) + 10;
				if (r3 == 10) {
					r4 = rand.nextInt(15) + 1;
				} else if (r3 == 15) {
					r4 = rand.nextInt(15);
				} else {
					r4 = rand.nextInt(16);
				}

				strH = array[r1] + array[r2];
				strL = array[r3] + array[r4];

				byte[] bytes = new byte[2];
				bytes[0] = (byte) (Integer.parseInt(strH, 16));
				bytes[1] = (byte) (Integer.parseInt(strL, 16));

				firstWord = new String(bytes);
				break;
			default:
				tempInt = rand.nextInt(10) + 48;
				firstWord = String.valueOf((char) tempInt);
				break;
			}
			finalWord += firstWord;
		}
		return finalWord;
	}
}

這個(gè)的效果：

3、兩個(gè)數(shù)相加的驗(yàn)證碼

運(yùn)行都是OK的，學(xué)到這里那兩個(gè)數(shù)的算式驗(yàn)證碼應(yīng)該如何實(shí)現(xiàn)呢？？？

首先，我們就要更改servlet里的kaptcha的默認(rèn)的KaptchaServlet，自己在寫(xiě)一個(gè),還有就是我們的是兩個(gè)數(shù)的算法，那也就要更改驗(yàn)證碼長(zhǎng)度的長(zhǎng)度，還有更改我們上面實(shí)現(xiàn)的中文和字母換回默認(rèn)值。

先更改一下web.xml:(自行尋找進(jìn)行更換)

<servlet-class>
			com.kaptcha.KaptchaServlet
		</servlet-class>

	<init-param>
	<description>文本實(shí)現(xiàn)類(lèi)</description>
	<param-name>kaptcha.textproducer.impl</param-name>
	<param-value>
		com.google.code.kaptcha.text.impl.DefaultTextCreator
	</param-value>
</init-param>

		<init-param>
			<description>驗(yàn)證碼長(zhǎng)度 2</description>
			<param-name>kaptcha.textproducer.char.length</param-name>
			<param-value>2</param-value>
		</init-param>

KaptchaServlet.java:

package com.kaptcha;

import com.google.code.kaptcha.Producer;
import com.google.code.kaptcha.util.Config;

import javax.imageio.ImageIO;
import javax.servlet.Servlet;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Properties;

public class KaptchaServlet extends HttpServlet implements Servlet {
	private Properties props;
	private Producer kaptchaProducer;
	private String sessionKeyValue;

	public KaptchaServlet() {
		this.props = new Properties();

		this.kaptchaProducer = null;

		this.sessionKeyValue = null;
	}

	public void init(ServletConfig conf) throws ServletException {
		super.init(conf);

		ImageIO.setUseCache(false);

		Enumeration initParams = conf.getInitParameterNames();
		while (initParams.hasMoreElements()) {
			String key = (String) initParams.nextElement();
			String value = conf.getInitParameter(key);
			this.props.put(key, value);
		}

		Config config = new Config(this.props);
		this.kaptchaProducer = config.getProducerImpl();
		this.sessionKeyValue = config.getSessionKey();
	}

	public void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		resp.setDateHeader("Expires", 0L);

		resp.setHeader("Cache-Control", "no-store, no-cache, must-revalidate");

		resp.addHeader("Cache-Control", "post-check=0, pre-check=0");

		resp.setHeader("Pragma", "no-cache");

		resp.setContentType("image/jpeg");

		String capText = this.kaptchaProducer.createText();
		String s1 = capText.substring(0, 1);
		String s2 = capText.substring(1, 2);
		int r = Integer.valueOf(s1).intValue() + Integer.valueOf(s2).intValue();

		req.getSession().setAttribute(this.sessionKeyValue, String.valueOf(r));

		BufferedImage bi = this.kaptchaProducer.createImage(s1+"+"+s2+"=?");

		ServletOutputStream out = resp.getOutputStream();

		ImageIO.write(bi, "jpg", out);
		try {
			out.flush();
		} finally {
			out.close();
		}
	}
}

效果為：