1. Configure Maven coordinates
<!-- https://mvnrepository.com/artifact/com.github.penggle/kaptcha -->
<dependency>
<groupId>com.github.penggle</groupId>
<artifactId>kaptcha</artifactId>
<version>2.3.2</version>
</dependency>
2. Configure Web.xml
<!-- Configure the verification code plugin servlet class-->
<servlet>
<servlet-name>kaptcha</servlet-name>
<servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>
<!-- Configure parameters for the verification code plugin servlet class -->
<!-- Border setting yes no -->
<init-param>
<param-name>kaptcha.border</param-name>
<param-value>no</param-value>
</init-param>
<!-- Border color color name such as: red blue black, etc. It can also be RGB: 105,179,90 -->
<init-param>
<param-name>kaptcha.border.color</param-name>
<param-value>red</param-value>
</init-param>
<!-- border width-->
<init-param>
<param-name>kaptcha.border.thickness</param-name>
<param-value>5</param-value>
</init-param>
<!-- The character source of the verification code is compatible with Chinese -->
<init-param>
<param-name>kaptcha.textproducer.char.string</param-name>
<param-value> 1234567890 character source to generate verification code </param-value>
</init-param>
<!-- Number of characters to generate result-->
<init-param>
<param-name>kaptcha.textproducer.char.length</param-name>
<param-value>5</param-value>
</init-param>
<!-- character font to generate the result -->
<init-param>
<param-name>kaptcha.textproducer.font.names</param-name>
<param-value>Microsoft Yahei,Arial,Italic</param-value>
</init-param>
<!-- Character size of the generated result -->
<init-param>
<param-name>kaptcha.textproducer.font.size</param-name>
<param-value>40</param-value>
</init-param>
<!-- Character color of the generated result -->
<init-param>
<param-name>kaptcha.textproducer.font.color</param-name>
<param-value>blue</param-value>
</init-param>
<!-- Character kerning of the resulting result -->
<init-param>
<param-name>kaptcha.textproducer.char.space</param-name>
<param-value>2</param-value>
</init-param>
<!-- Interference Line Generator-->
<init-param>
<param-name>kaptcha.noise.impl</param-name>
<param-value>com.google.code.kaptcha.impl.DefaultNoise</param-value>
</init-param>
<!-- Interference line color-->
<init-param>
<param-name>kaptcha.noise.color</param-name>
<param-value>BLACK</param-value>
</init-param>
<!-- Interference line background gradient color gradient from left to right -->
<init-param>
<param-name>kaptcha.background.clear.from</param-name>
<param-value>green</param-value>
</init-param>
<!-- Interference line background gradient color gradient from right to left -->
<init-param>
<param-name>kaptcha.background.clear.to</param-name>
<param-value>yellow</param-value>
</init-param>
<!-- Captcha image width-->
<init-param>
<param-name>kaptcha.image.width</param-name>
<param-value>200</param-value>
</init-param>
<!-- Captcha image height-->
<init-param>
<param-name>kaptcha.image.height</param-name>
<param-value>50</param-value>
</init-param>
</servlet>
<!-- CAPTCHA request name mapping
//Get the verification code from the server from the session
String kaptchaServer = (String)request.getSession().getAttribute
(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
-->
<servlet-mapping>
<servlet-name>kaptcha</servlet-name>
<url-pattern>/mykaptcha</url-pattern>
</servlet-mapping>
Third, write jsp pages
4. Verification
Five, the error solution
严重: Servlet.service() for servlet jsp threw exception
java.lang.LinkageError: loader constraint violation: loader (instance of org/apache/jasper/servlet/JasperLoader) previously initiated loading for a different type with name "javax/servlet/http/HttpServletRequest"
<!-- Add Servlet -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
</dependency>
replace with
<!-- Add Servlet -->
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
<scope>provided</scope>
</dependency>
