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标题 jquery实现无刷新验证码的简单实例
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    下面小编就为大家带来一篇jquery实现无刷新验证码的简单实例。小编觉得挺不错的，现在分享给大家，也给大家做个参考。
    1. 思路:
    页面上的验证码图片是servlet,采用jquery实现异步校验信息
    2. 所用到的文件
    VerifyCodeServlet.java   --用于生成图片的servlet
    ResultServlet.java  --用于校验验证码正确性的servlet
    verifyCode.js  --校验的js文件
    jquery.js  --jquery包里的源文件
    verifyCode.jsp  --页面
    3. 代码
    VerifyCodeServlet.java
    Java代码
    import java.awt.Color;  
    import java.awt.Font;  
    import java.awt.Graphics2D;  
    import java.awt.image.BufferedImage;  
    import java.util.Random;  
    import javax.imageio.ImageIO;  
    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 VerifyCodeServlet 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 = 20;  
      // 验证码字符个数  
      private int codeCount = 4;  
      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) {  
        }  
        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, 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.BLACK);  
        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, 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("validateCode", randomCode.toString());  
        // 禁止图像缓存。  
        resp.setHeader("Pragma", "no-cache");  
        resp.setHeader("Cache-Control", "no-cache");  
        resp.setDateHeader("Expires", 0);  
        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();  
      }  
    } 
    import java.awt.Color;
    import java.awt.Font;
    import java.awt.Graphics2D;
    import java.awt.image.BufferedImage;
    import java.util.Random;
    import javax.imageio.ImageIO;
    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 VerifyCodeServlet 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 = 20;
     // 验证码字符个数
     private int codeCount = 4;
     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) {
     }
     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, 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.BLACK);
     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, 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("validateCode", randomCode.toString());
     // 禁止图像缓存。
     resp.setHeader("Pragma", "no-cache");
     resp.setHeader("Cache-Control", "no-cache");
     resp.setDateHeader("Expires", 0);
     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();
     }
    }
    ResultServlet.java
    Java代码 
    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 ResultServlet extends HttpServlet {  
      /**  
       * The doGet method of the servlet. <br>  
       *  
       * This method is called when a form has its tag value method equals to get.  
       *  
       * @param request the request send by the client to the server  
       * @param response the response send by the server to the client  
       * @throws ServletException if an error occurred  
       * @throws IOException if an error occurred  
       */ 
      public void doGet(HttpServletRequest request, HttpServletResponse response)  
          throws ServletException, IOException {  
        doPost(request, response);  
      }  
      /**  
       * The doPost method of the servlet. <br>  
       *  
       * This method is called when a form has its tag value method equals to post.  
       *  
       * @param request the request send by the client to the server  
       * @param response the response send by the server to the client  
       * @throws ServletException if an error occurred  
       * @throws IOException if an error occurred  
       */ 
      public void doPost(HttpServletRequest request, HttpServletResponse response)  
          throws ServletException, IOException {  
        response.setContentType("text/html;charset=utf-8");  
        String validateC = (String) request.getSession().getAttribute("validateCode");  
        String veryCode = request.getParameter("c");  
        PrintWriter out = response.getWriter();  
        if(veryCode==null||"".equals(veryCode)){  
          out.println("验证码为空");  
        }else{  
          if(validateC.equals(veryCode)){  
            out.println("验证码正确");  
          }else{  
            out.println("验证码错误");  
          }  
        }  
        out.flush();  
        out.close();  
      }  
    } 
    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 ResultServlet extends HttpServlet {
     /**
     * The doGet method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to get.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
     public void doGet(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
     doPost(request, response);
     }
     /**
     * The doPost method of the servlet. <br>
     *
     * This method is called when a form has its tag value method equals to post.
     * 
     * @param request the request send by the client to the server
     * @param response the response send by the server to the client
     * @throws ServletException if an error occurred
     * @throws IOException if an error occurred
     */
     public void doPost(HttpServletRequest request, HttpServletResponse response)
      throws ServletException, IOException {
     response.setContentType("text/html;charset=utf-8");
     String validateC = (String) request.getSession().getAttribute("validateCode");
     String veryCode = request.getParameter("c");
     PrintWriter out = response.getWriter();
     if(veryCode==null||"".equals(veryCode)){
      out.println("验证码为空");
     }else{
      if(validateC.equals(veryCode)){
      out.println("验证码正确");
      }else{
      out.println("验证码错误");
      }
     }
     out.flush();
     out.close();
     }
    }
    verifyCode.js
    Js代码
    function changeImg(){  
      var imgSrc = $("#imgObj");  
      var src = imgSrc.attr("src");  
      imgSrc.attr("src",chgUrl(src));  
    }  
    //时间戳  
    //为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳  
    function chgUrl(url){  
      var timestamp = (new Date()).valueOf();  
      url = url.substring(0,17);  
      if((url.indexOf("&")>=0)){  
        url = url + "×tamp=" + timestamp;  
      }else{  
        url = url + "?timestamp=" + timestamp;  
      }  
      return url;  
    }  
    function isRightCode(){  
      var code = $("#veryCode").attr("value");  
      code = "c=" + code;  
      $.ajax({  
        type:"POST",  
        url:"resultServlet",  
        data:code,  
        success:callback  
      });  
    }  
    function callback(data){  
      $("#info").html(data);  
    } 
    function changeImg(){
     var imgSrc = $("#imgObj");
     var src = imgSrc.attr("src");
     imgSrc.attr("src",chgUrl(src));
    }
    //时间戳
    //为了使每次生成图片不一致，即不让浏览器读缓存，所以需要加上时间戳
    function chgUrl(url){
     var timestamp = (new Date()).valueOf();
     url = url.substring(0,17);
     if((url.indexOf("&")>=0)){
     url = url + "×tamp=" + timestamp;
     }else{
     url = url + "?timestamp=" + timestamp;
     }
     return url;
    }
    function isRightCode(){
     var code = $("#veryCode").attr("value");
     code = "c=" + code;
     $.ajax({
     type:"POST",
     url:"resultServlet",
     data:code,
     success:callback
     });
    }
    function callback(data){
     $("#info").html(data);
    }
    verifyCode.jsp
    Html代码
    <%@ page language="java" contentType="text/html; charset=UTF-8"  
      pageEncoding="UTF-8"%>  
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">  
    <html>  
      <head>  
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">  
        <script type="text/javascript" src="js/verifyCode.js"></script>  
        <script type="text/javascript" src="js/jquery.js"></script>  
        <title>test verify code</title>  
      </head>  
      <body>  
        <input id="veryCode" name="veryCode" type="text"/>  
        <img id="imgObj" src="verifyCodeServlet"/>  
        <a href="#" onclick="changeImg()">换一张</a>  
        <input type="button" value="验证" onclick="isRightCode()"/>  
        <div id="info"></div>  
      </body>  
    </html> 
    以上这篇jquery实现无刷新验证码的简单实例就是小编分享给大家的全部内容了，希望能给大家一个参考
随便看

　

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更新时间：2025/5/19 17:03:54