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>

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，也希望大家多多支持。