Jquery实现无刷新验证码

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

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

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

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

<%@ 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" alt="" src="verifyCodeServlet"/>  
        <a href="#" onclick="changeImg()">换一张</a>  
        <input type="button" value="验证" onclick="isRightCode()"/>  
        <div id="info"></div>  
    </body>  
</html> 

[url]http://www.iteye.com/post/608953#[/url]

评论

1 楼 l_zh_y 2012-07-06  

点击更换验证码时，input id="veryCode" name="veryCode" type="text"/> 如何更新呢