验证码

1.jaba文件

public class ValidateCodeServlet extends HttpServlet{
 /** 验证码图片的宽度 */
    private int width = 60; 
    /** 验证码图片的高度 */ 
    private int height = 25; 
    /** 验证码字符个数 */ 
    private int codeCount = 4; 
    // 字符间距 
    private int x = 0; 
    // 字体高度 
    private int fontHeight; 
    private int codeY; 
 
    char[] codeSequence = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 
            'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 
            'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' }; 
   
    /**
     * 初始化验证图片属性
     */ 
    public void init() throws ServletException { 
        // 从web.xml中获取初始信息 
        // 宽度 
        String strWidth = this.getInitParameter("width");
        // 高度 
        String strHeight = this.getInitParameter("height");
        // 字符个数 
        String strCodeCount = this.getInitParameter("codeCount");
 
        // 将配置的信息转换成数值 
        try { 
            if (strWidth != null && strWidth.length() != 0) { 
                width = Integer.parseInt(strWidth); 
            } 
            if (strHeight != null && strHeight.length() != 0) { 
                height = Integer.parseInt(strHeight); 
            } 
            if (strCodeCount != null && strCodeCount.length() != 0) { 
                codeCount = Integer.parseInt(strCodeCount); 
            } 
        } catch (NumberFormatException e) {
            e.printStackTrace();
        } 
 
        x = width / (codeCount + 1); 
        fontHeight = height - 2; 
        codeY = height - 4;
    }
    protected void service(HttpServletRequest req, HttpServletResponse resp) 
            throws ServletException, java.io.IOException {
        // 定义图像buffer 
        BufferedImage buffImg = new BufferedImage(width, height, 
                BufferedImage.TYPE_INT_RGB); 
        Graphics2D g = buffImg.createGraphics(); 
 
        // 创建一个随机数生成器类 
        Random random = new Random(); 
 
        // 将图像填充为白色 
        g.setColor(Color.WHITE); 
        g.fillRect(0, 0, width, height); 
 
        // 创建字体，字体的大小应该根据图片的高度来定。 
        Font font = new Font("Fixedsys", Font.PLAIN | Font.BOLD, fontHeight); 
        // 设置字体。 
        g.setFont(font); 
 
        // 画边框。 
        g.setColor(Color.BLACK); 
        g.drawRect(0, 0, width - 1, height - 1); 
 
        // 随机产生160条干扰线，使图象中的认证码不易被其它程序探测到。 
        g.setColor(Color.pink); 
        for (int i = 0; i < 160; i++) { 
            int x = random.nextInt(width); 
            int y = random.nextInt(height); 
            int xl = random.nextInt(12); 
            int yl = random.nextInt(12); 
            g.drawLine(x, y, x + xl, y + yl); 
        } 
 
        // randomCode用于保存随机产生的验证码，以便用户登录后进行验证。 
        StringBuffer randomCode = new StringBuffer(); 
        int red = 0, green = 0, blue = 0; 
 
        // 随机产生codeCount数字的验证码。 
        for (int i = 0; i < codeCount; i++) { 
            // 得到随机产生的验证码数字。 
            String strRand = String.valueOf(codeSequence[random.nextInt(36)]); 
            // 产生随机的颜色分量来构造颜色值，这样输出的每位数字的颜色值都将不同。 
            red = random.nextInt(255); 
            green = random.nextInt(255); 
            blue = random.nextInt(255); 
 
            // 用随机产生的颜色将验证码绘制到图像中。 
            g.setColor(new Color(red, green, blue)); 
            g.drawString(strRand, (i + 1) * x - 6, codeY); 
 
            // 将产生的四个随机数组合在一起。 
            randomCode.append(strRand); 
        } 
        // 将四位数字的验证码保存到Session中。 
        HttpSession session = req.getSession();
        session.setAttribute("verificationCodeCGS" , randomCode.toString()); 
 
        // 禁止图像缓存。 
        resp.setHeader("Pragma", "no-cache"); 
        resp.setHeader("Cache-Control", "no-cache"); 
        resp.setDateHeader("Expires", 0); 
 
        // 设置响应的类型格式为图片格式 
        resp.setContentType("image/jpeg"); 
 
        // 将图像输出到Servlet输出流中。 
        ServletOutputStream sos = resp.getOutputStream(); 
        ImageIO.write(buffImg, "jpeg", sos); 
        sos.close();
 }
   
}

 

2.web.xml

<servlet> 
  <servlet-name>ValidateCodeServlet</servlet-name>
  <servlet-class>com.kplus.lu.servlet.ValidateCodeServlet</servlet-class> 
  <init-param> 
   <param-name>width</param-name> 
   <param-value>60</param-value> 
  </init-param>
  <init-param> 
   <param-name>height</param-name> 
   <param-value>20</param-value> 
  </init-param> 
  <init-param> 
   <param-name>codeCount</param-name> 
   <param-value>4</param-value> 
  </init-param> 
 </servlet>
 <servlet-mapping> 
  <servlet-name>ValidateCodeServlet</servlet-name> 
  <url-pattern>/validatecode.jpg</url-pattern> 
 </servlet-mapping>

 

3.html

<img src="validatecode.jpg" id="imgCode2" onclick="changeCode();" width="25%" style="cursor:pointer;"/>

<script>

function changeCode(){
  $("#imgCode2").attr("src","");//为了兼容IE
  $("#imgCode2").attr("src","validatecode.jpg");
}

</script>