使用插件生成验证码

矫情吗；* 2021-09-20 16:14 344阅读 0赞

**第一步:导入插件,放在/ValidateCode/WebContent/WEB-INF/lib/中.**

下载地址: http://www.java2s.com/Code/Jar/k/Downloadkaptcha23jar.htm

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNjc5ODE4_size_16_color_FFFFFF_t_70][]

**第二步:配置web.xml**

<servlet>
          <servlet-name>Kaptcha</servlet-name>
          <servlet-class>com.google.code.kaptcha.servlet.KaptchaServlet</servlet-class>
      </servlet>
      <servlet-mapping>
          <servlet-name>Kaptcha</servlet-name>
          <url-pattern>/kaptcha.jpg</url-pattern>
      </servlet-mapping>

**第三步:画页面**

<%@ page language="java" contentType="text/html; charset=utf-8"
        pageEncoding="utf-8"%>
    <!DOCTYPE html>
    <html>
    <head>
    <meta charset="ISO-8859-1">
    <title>Insert title here</title>
    <script type="text/javascript">
           function reloadCode(){
        	   document.getElementById("imgCode").src="/ValidateCode/kaptcha.jpg"+Math.random();
           }
    </script>
    </head>
    <body>
        <form action="/ValidateCode/kapServlet" method="post">
             <label for="username">用户名:</label>
             <input type="text" id="username" name="username"><br>
             <label for="pwd">密 码:</label>
             <input type="password" id="pwd" name="password"><br>
             <label for="code">验证码:</label>
             <input type="text" name="usercode">
             <img src="/ValidateCode/kaptcha.jpg" id="imgCode" onclick="reloadCode()"><br>
             <input type="submit" value="提交">
        </form>
    </body>
    </html>

action是表示向何处发送数据,写完servlet验证之后再填写.

**第四步:写Servlet**

package yyy.servlet;
    
    import java.io.IOException;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class KapServlet extends HttpServlet {
    	private static final long serialVersionUID = 1L;
        
    	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/html;charset=utf-8");
    		
    		// 假设注册的用户名和密码已经通过校验，我还需要校验验证码是否正确
    		// 获取用户在页面输入的验证码
    		String userCode = request.getParameter("usercode"); //要与表单中验证码输入框中name属性的值一样.
    		// 获取我们后台生成的验证码的结果
    		String validateCodeResult =((String)request.getSession().getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY));	
    		System.out.println(validateCodeResult);
    		// 比对两个验证码是否一致
    		if(validateCodeResult.equals(userCode)) {
    			response.getWriter().write("恭喜，校验成功!");
    		} else {
    			response.getWriter().write("很遗憾，校验失败!");
    		}
    	}
    
    		protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    		// TODO Auto-generated method stub
    		doGet(request, response);
    	}
    
    }

**第五步:继续再配置web.xml**

<servlet>
           <servlet-name>KapServlet</servlet-name>
           <servlet-class>yyy.servlet.KapServlet</servlet-class>
      </servlet>
      <servlet-mapping>
           <servlet-name>KapServlet</servlet-name>
           <url-pattern>/kapServlet</url-pattern>
      </servlet-mapping>

运行结果:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNjc5ODE4_size_16_color_FFFFFF_t_70 1][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNjc5ODE4_size_16_color_FFFFFF_t_70]: /images/20210920/caa35be17d8c4aa49a14a5b5ecebe7a7.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQxNjc5ODE4_size_16_color_FFFFFF_t_70 1]: /images/20210920/a7a250b6b78b453786bd931a4abd7c0c.png