浅谈用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

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

Java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();
    urlurl = url.substring(0,17);
    if((url.indexOf("&")>=0)){
        urlurl = url + "×tamp=" + timestamp;
    }else{
        urlurl = 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();
 urlurl = url.substring(0,17);
 if((url.indexOf("&")>=0)){
  urlurl = url + "×tamp=" + timestamp;
 }else{
  urlurl = 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

Java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" 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.javaeye.com/post/608953#[/url]