jquery实现无刷新图片验证(转)

ImageServlet.java

 package com.yu;
  
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  import javax.servlet.http.HttpSession;
  import javax.servlet.ServletException;
  import javax.servlet.ServletOutputStream;
  import javax.imageio.ImageIO;
  import java.io.IOException;
  import java.awt.image.BufferedImage;
  import java.awt.*;
  import java.util.Random;
  
  
  public class ImageServlet extends HttpServlet {
      protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
          doGet(request, response);
      }
  
      protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
     }
 
     // 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");
          
 56         System.out.println("strWidth=="+strWidth+"strHeight=="+strHeight+"strCodeCount=="+strCodeCount);
  
          // 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.cyan);
        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

 

package com.yu;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import java.io.IOException;
import java.io.PrintWriter;

/**
 * Created by IntelliJ IDEA.
 * User: Administrator
 * Date: 2009-11-18
 * Time: 21:25:44
 * To change this template use File | Settings | File Templates.
 */
public class ResultServlet extends HttpServlet {


        public void doGet(HttpServletRequest request, HttpServletResponse response)
                throws ServletException, IOException {

            doPost(request, response);
        }
        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");
            System.out.println(veryCode);
            System.out.println(validateC);
            PrintWriter out = response.getWriter();
            veryCode=veryCode.toUpperCase();
            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();
        }

    }

 changeImg.js

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();
          urlurl = url.substring(0, 17);
         if ((url.indexOf("?") >= 0)) {
             urlurl = url + "&t=" + timestamp;
         } else {
             urlurl = url + "?t=" + timestamp;
         }
         return urlurl;
     }
}
function isRightCode() {
     var code = $("#veryCode").attr("value");
 
     $.ajax({
         type:"POST",
         url:"ResultServlet",
         data:"c="+code,
         success:callback
     });
}
 
function callback(data) {
     $("#info").html(data);
}
 

 ajax.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
 <html>
 <head><title>ajax</title>
     <script type="text/javascript" src="/js/jquery-1.2.6.js"></script>
     <script type="text/javascript" src="/js/changImage.js"></script>
 </head>
 <body>
  <input id="veryCode" name="veryCode" type="text"/>
         <img id="imgObj" alt="" src="ImageServlet"/>
          <a href="#" onclick="changeImg()">换一张</a>
         <input type="button" value="验证" onclick="isRightCode()"/>
          <div id="info"></div> 
 </body>
 </html>

  web.xml

<?xml version="1.0" encoding="UTF-8"?>
 <web-app xmlns="http://java.sun.com/xml/ns/javaee"
          xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
           http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
          version="2.5">
 
     <servlet>
         <servlet-name>AjaxServlet</servlet-name>
         <servlet-class>com.yu.AjaxServlet</servlet-class>
     </servlet>
     <servlet>
         <servlet-name>ImageServlet</servlet-name>
         <servlet-class>com.yu.ImageServlet</servlet-class>
         <init-param>
             <param-name>width</param-name>
             <param-value>80</param-value>
         </init-param>
         <init-param>
             <param-name>height</param-name>
             <param-value>25</param-value>
         </init-param>
         <init-param>
             <param-name>codeCount</param-name>
             <param-value>4</param-value>
         </init-param>
     </servlet>
     <servlet>
         <servlet-name>ResultServlet</servlet-name>
         <servlet-class>com.yu.ResultServlet</servlet-class>
     </servlet>
     <servlet-mapping>
         <servlet-name>AjaxServlet</servlet-name>
         <url-pattern>/AjaxServlet</url-pattern>
     </servlet-mapping>
     <servlet-mapping>
         <servlet-name>ImageServlet</servlet-name>
         <url-pattern>/ImageServlet</url-pattern>
     </servlet-mapping>
     <servlet-mapping>
         <servlet-name>ResultServlet</servlet-name>
         <url-pattern>/ResultServlet</url-pattern>
     </servlet-mapping>
 </web-app>