下面小编就为大家带来一篇jquery实现无刷新验证码的简单实例。小编觉得挺不错的，现在分享给大家，也给大家做个参考。

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.

*

* 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.

*

* 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.

*

* 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.

*

* 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"%>

换一张

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