jquery实现无刷新验证码的简单实例

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" 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>

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