kaptcha驗證碼的使用，kaptcha如何生成驗證碼

kaptcha驗證碼的使用
1.首先在pom.xml文件中導入Maven依賴

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

2.在web.xml文件中配置一個servlet

<servlet>
		<!-- 生成圖片的Servlet -->
		<servlet-name>Kaptcha</servlet-name>
		<servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>
		<!-- 是否有邊框 -->
	<init-param>		
               <param-name>kaptcha.border</param-name>
		<param-value>no</param-value>
	</init-param>
		<!-- 字體顏色 -->
		<init-param>
	    <param-name>kaptcha.textproducer.font.color</param-name>
		<param-value>red</param-value>
		</init-param>
	<!-- 圖片寬度 -->
		<init-param>
		<param-name>kaptcha.image.width</param-name>
		<param-value>135</param-value>
	</init-param>
		<!-- 使用哪些字符生成驗證碼 -->
	<init-param>
		<param-name>kaptcha.textproducer.char.string</param-name>
			<param-value>ACDEFHKPRSTWX345679</param-value>
		</init-param>
		<!-- 圖片高度 -->
		<init-param>
			<param-name>kaptcha.image.height</param-name>
			<param-value>50</param-value>
		</init-param>
		<!-- 字體大小 -->
		<init-param>
			<param-name>kaptcha.textproducer.font.size</param-name>
			<param-value>43</param-value>
		</init-param>
		<!-- 干擾線的顏色 -->
		<init-param>
			<param-name>kaptcha.noise.color</param-name>
			<param-value>black</param-value>
		</init-param>
		<!-- 字符個數 -->
		<init-param>
			<param-name>kaptcha.textproducer.char.length</param-name>
			<param-value>4</param-value>
		</init-param>
		<!-- 使用哪些字體 -->
		<init-param>
			<param-name>kaptcha.textproducer.font.names</param-name>
			<param-value>Arial</param-value>
		</init-param>
	</servlet>
	<!-- 映射的url -->
	<servlet-mapping>
		<servlet-name>Kaptcha</servlet-name>
		<url-pattern>/Kaptcha</url-pattern>
	</servlet-mapping>

3.頁面代碼如下

<div class="item-inner">
	<label for="j_captcha" class="item-title label">驗證碼</label>
	 <input id="j_captcha" name="j_captcha" type="text" 
	  class="form-control in" placeholder="驗證碼" />
		<div class="item-input">
					<img id="captcha_img" alt="點擊更換" title="點擊更換"
			               onclick="changeVerifyCode(this)" src="../Kaptcha" />
		</div>
</div>

向後端提交數據

var verifyCodeActual = $('#j_captcha').val();
		if (!verifyCodeActual) {
			$.toast('請輸入驗證碼！');
			return;
		}
		formData.append("verifyCodeActual", verifyCodeActual);

4.js交互

function changeVerifyCode(img) {
	img.src = "../Kaptcha?" + Math.floor(Math.random() * 100);
}

5.後端驗證

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.equalsIgnoreCase(verifyCodeExpected)) {
			return false;
		}
		return true;
	}
}



import javax.servlet.http.HttpServletRequest;

public class HttpServletRequestUtil {
	public static int getInt(HttpServletRequest request, String name) {

		try {
			return Integer.decode(request.getParameter(name));
		} catch (Exception e) {
			return -1;
		}
	}

	public static long getLong(HttpServletRequest request, String name) {

		try {
			return Long.valueOf(request.getParameter(name));
		} catch (Exception e) {
			return -1;
		}
	}

	public static Double getDouble(HttpServletRequest request, String name) {

		try {
			return Double.valueOf(request.getParameter(name));
		} catch (Exception e) {
			return -1d;
		}
	}

	public static Boolean getBoolean(HttpServletRequest request, String name) {

		try {
			return Boolean.valueOf(request.getParameter(name));
		} catch (Exception e) {
			return false;
		}
	}

	public static String getString(HttpServletRequest request, String name) {
		try {
			String result = request.getParameter(name);
			if (result != null) {
				result = result.trim();
			}
			if ("".equals(result))
				result = null;
			return result;
		} catch (Exception e) {
			return null;
		}

	}
}