Kaptcha生成验证码

1.导入jar包如kaptchar.2.3.jar 2.添加配置文件

3.使用方法`

代码语言：javascript复制


 function changeR(node){ // 用于点击时产生不同的验证码 node.src = "/randomcode.jpg?time=" new Date().getTime() ; }

获取验证码并校验代码语言：javascript复制

<body>
    <%
        // 检查是否是正确的验证码
        String k = (String) session
                .getAttribute(com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY);
        String str = request.getParameter("r");
        if (k.equals(str))
            out.print("true");
        out.print(k   "---"   str);
    %>
</body>

4.说明使用加法验证码需要注意（重写）

代码语言：javascript复制

import com.google.code.kaptcha.Producer;
import com.google.code.kaptcha.util.Config;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Properties;
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 javax.servlet.http.HttpSession;

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();
        //直接从验证码集合中选取四位，前两位作为加数1，后两位作为加数2 因此配置需要填写**4**位验证码
        String s1 = capText.substring(0, 2);
        String s2 = capText.substring(2, 4); 
        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();
        }
    }
}

使用文字验证码直接修改文本集合即可，也可以重写类如下

代码语言：javascript复制

` public String getText() { 
 int length = getConfig().getTextProducerCharLength(); 
 //char[] charS = getConfig().getTextProducerCharString();

代码语言：javascript复制

    String[] s = new String[]{"慕","课","网","教","程","验","证","码","实","例"};

    Random rand = new Random();
    StringBuffer sb = new StringBuffer();
    for(int i = 0; i < length; i  ){
        int ind = rand.nextInt(s.length);
        sb.append(s[ind]);
    }
    return sb.toString();
}`

jar 验证码

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