jsp+servlet验证码验证

骑猪看日落 2021-05-03 10:25 622阅读 0赞

# 一. servlet绘制生成验证码 #

index.jsp – 前台页面

<body>
      <form action="<%=request.getContextPath() %>/servlet/LoginServlet" method="get">
          验证码:<input type="text" name="VerifyCode" size=6 />
           <img onclick="reloadCode()" src="<%=request.getContextPath() %>/servlet/ImgServlet" id="img" /> <br>
           <input type="submit" name="submit" value="提交" /> 
      </form>   
            <script> function reloadCode(){ document.getElementById("img").src="<%=request.getContextPath() %>/servlet/ImgServlet?"+Math.random();; } </script>
      </body>

ImgServlet.java – 绘制验证码图片

package servlet;
    
    import java.awt.Color;
    import java.awt.Graphics;
    import java.awt.image.BufferedImage;
    import java.io.IOException;
    import java.io.PrintWriter;
    import java.util.Random;
    
    import javax.imageio.ImageIO;
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class ImgServlet extends HttpServlet {
    
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            BufferedImage bfi = new BufferedImage(68, 22, BufferedImage.TYPE_INT_RGB); //图像缓冲区
            Graphics g = bfi.getGraphics();
            StringBuffer sb = new StringBuffer();
            /*画背景框*/
            Color color = new Color(200,215,250); 
            g.setColor(color);
            g.fillRect(0, 0, 68,30); 
            /*第一个数字*/
            Random r = new Random();
            int tmp1 = r.nextInt(20);
            g.setColor(new Color(r.nextInt(100),r.nextInt(100),r.nextInt(100))); //设置随机颜色
            g.drawString(tmp1+"",3, 18);
            /*加号*/
            g.setColor(new Color(r.nextInt(100),r.nextInt(100),r.nextInt(100))); //设置随机颜色
            g.drawString("+",18, 18); 
            /*第二个数字*/
            int tmp2 = r.nextInt(20);
            g.setColor(new Color(r.nextInt(100),r.nextInt(100),r.nextInt(100))); //设置随机颜色
            g.drawString(tmp2+"",33, 18); 
            /*等号*/
            g.setColor(new Color(r.nextInt(100),r.nextInt(100),r.nextInt(100))); //设置随机颜色
            g.drawString("=",48, 18); 
            /*问号*/
            g.setColor(new Color(r.nextInt(100),r.nextInt(100),r.nextInt(100))); //设置随机颜色
            g.drawString("?",57, 18);
            /*保存到session*/
            int result = tmp1+tmp2;
            request.getSession().setAttribute("VerifyCode", result+"");
            /*写入response输出流*/
            ImageIO.write(bfi, "JPG", response.getOutputStream());
        }
    }

LoginServlet.java – 校验与处理

package servlet;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class LoginServlet extends HttpServlet {
    
    
        public void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {
            response.setContentType("text/html;charset=utf-8");
            String re = request.getParameter("VerifyCode");
            String answer =(String)request.getSession().getAttribute("VerifyCode");
            PrintWriter out = response.getWriter();
            if(re.equals(answer)){  
                out.printf("验证成功");
            }else{
                out.printf("验证失败");
            }
            out.flush();
            out.close();
        }
    
    }

# 二. 使用kaptcha验证码组件 #

1.. 添加kaptcha的jar包到项目lib库  
2..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>

3.. 页面调用

<body>
      <form action="<%=request.getContextPath() %>/servlet/LoginServlet" method="get">
          验证码:<input type="text" name="VerifyCode" size=6 />
           <img onclick="reloadCode()" src="kaptcha.jpg" id="img" /> <br>
           <input type="submit" name="submit" value="提交" /> 
      </form>   
            <script> function reloadCode(){ document.getElementById("img").src="kaptcha.jpg?"+Math.random();; } </script>
      </body>

4..验证用户输入是否正确

/*获取session中的验证码*/
    String captcha = ((String) request.getSession().getAttribute(
    com.google.code.kaptcha.Constants.KAPTCHA_SESSION_KEY));

## kaptcha详细配置： ##

在web.xml的该servlet中配置初始化参数

| 属性                       | param name                       | param value                                                  |
| -------------------------- | -------------------------------- | ------------------------------------------------------------ |
| 文本实现类                 | kaptcha.textproducer.impl        | com.google.code.kaptcha.text.impl.DefaultTextCreator         |
| 验证码值配置               | kaptcha.textproducer.char.string | abcde2345678gfynmnpwx(自定义)                                |
| 验证码的长度               | kaptcha.textproducer.char.length | 数字                                                         |
| 字体                       | kaptcha.textproducer.font.names  | 字体                                                         |
| 字体颜色                   | kaptcha.textproducer.font.color  | r,g,b 或者 white,black,blue                                  |
| 验证码宽度                 | kaptcha.textproducer.img.width   | 数字                                                         |
| 验证码高度                 | kaptcha.textproducer.img.height  | 数字                                                         |
| 干扰实现类                 | kaptcha.noise.impl               | com.google.code.kaptcha.impl.DefaultNoise/NoNoise            |
| 干扰颜色                   | kaptcha.noise.color              | r,g,b 或者 white,black,blue                                  |
| 图片样式                   | kaptcha.obscurificator.impl      | 水纹com.google.code.kaptcha.impl.WaterRipple； 鱼眼com.google.code.kaptcha.impl.FishEyeGimpy； 阴影com.google.code.kaptcha.impl.ShadowGimpy |
| 背景实现类                 | kaptcha.background.impl          | com.google.code.kaptcha.impl.DefaultBackground               |
| 背景渐变色(开始/结束)      | kaptcha.background.clear.from/to | r,g,b 或者 white,black,blue                                  |
| 文字渲染器                 | kaptcha.word.impl                | com.google.code.kaptcha.text.impl.DefaultWordRenderer        |
| session中存放验证码的key键 | kaptcha.session.key              | KAPTCHA_SESSION_KEY                                          |