现在大部分的登录或验证系统都拥有了字母或数字图片的验证码，自己也一时兴起，根据网上的demo自己也尝试了一下，很有意思！
下面则是这次实验的效果图：
1.登陆页jsp：
<html>
<head><base href="/">
<meta charset="UTF-8">
<title>登陆页面</title>
<meta name="viewport"
content="width=device-width,initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no"/>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" href="css/login.css">
<script language="javascript" src="js/jquery-1.9.0.min.js"></script>
<script language="javascript" src="js/login/login.js"></script>
</head>
<body>
<div class="login_form">
<form name='myForm' action='' method='post' >
<input type="text" name="userName" id="userName" placeholder="请输入用户名">
<input type="password" name="password" id="password" placeholder="请输入密码">
</form>
<input class="check_input" type="text" placeholder="请输入验证码">
<img id="imgVerify" src="" alt="点击更换验证码" width="112" height="36" onclick="getVerify(this);">//首次获取验证码图片，也可在此将src设为访问路径/getVerify
<div class="login_form_warn_lable"></div>
<div class="login_form_warn">
<span class="warn_text">用户名或密码错误</span>
</div>
<div class="login_form_submit">
<button class="btn_submit" onclick="login();">登 录</button>
</div>
</div>
</body>
</html>
2.登陆页面js：
$(document.body).ready(function () {
//首次获取验证码
$("#imgVerify").attr("src","/getVerify?"+Math.random());
});
//点击登录按钮
function login(){
//校验验证码
checkSum();
}
//提交表单
function submitForm(){
document.myForm.action = "/login";
document.myForm.submit();
}
//获取验证码
function getVerify(obj){
obj.src = "/getVerify?"+Math.random();
}
//校验验证码
function checkSum(){
var inputStr = $(".check_input").val();
if(inputStr!=null && inputStr!=""){
inputStr = inputStr.toUpperCase();//将输入的字母全部转换成大写
$.ajax({
url : "checkVerify",
data: {inputStr:inputStr},
success : function(datas) {
if(datas == "T"){
submitForm();//提交表单
}else{
$(".check_input").val("");
$(".warn_text").text("验证码输入错误！");
$(".login_form_warn").css("display","block");
}
}
});
}else{
$(".warn_text").text("请输入验证码");
$(".login_form_warn").css("display","block");
}
}
3.（springMVC框架）java后台controller获取和校验验证码：
/**
* 登录页面生成验证码
*/
@RequestMapping(value = "getVerify")
public void getVerify(HttpServletRequest request, HttpServletResponse response){
response.setContentType("image/jpeg");//设置相应类型,告诉浏览器输出的内容为图片
response.setHeader("Pragma", "No-cache");//设置响应头信息，告诉浏览器不要缓存此内容
response.setHeader("Cache-Control", "no-cache");
response.setDateHeader("Expire", 0);
RandomValidateCode randomValidateCode = new RandomValidateCode();
try {
randomValidateCode.getRandcode(request, response);//输出验证码图片方法
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 登录页面校验验证码
*/
@RequestMapping(value = "checkVerify")
@ResponseBody
public String checkVerify(String inputStr, HttpSession session){
//从session中获取随机数
String random = (String) session.getAttribute("RANDOMVALIDATECODEKEY");
if(random.equals(inputStr)){
return "TURE";//验证码正确
}else{
return "FALSE";//验证码错误
}
}
4.验证码图片生成工具类：
/**
* 验证码生成类
* <p>
* @author admin
*
*/
public class RandomValidateCode {
public static final String RANDOMCODEKEY= "RANDOMVALIDATECODEKEY";//放到session中的key
//private String randString = "0123456789";//随机产生只有数字的字符串 private String
private String randString = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生只有字母的字符串
//private String randString = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//随机产生数字与字母组合的字符串
private int width = 95;// 图片宽
private int height = 25;// 图片高
private int lineSize = 40;// 干扰线数量
private int stringNum = 4;// 随机产生字符数量
private Random random = new Random();
/*
* 获得字体
*/
private Font getFont() {
return new Font("Fixedsys", Font.CENTER_BASELINE, 18);
}
/*
* 获得颜色
*/
private Color getRandColor(int fc, int bc) {
if (fc > 255)
fc = 255;
if (bc > 255)
bc = 255;
int r = fc + random.nextInt(bc - fc - 16);
int g = fc + random.nextInt(bc - fc - 14);
int b = fc + random.nextInt(bc - fc - 18);
return new Color(r, g, b);
}
/**
* 生成随机图片
*/
public void getRandcode(HttpServletRequest request,
HttpServletResponse response) {
HttpSession session = request.getSession();
// BufferedImage类是具有缓冲区的Image类,Image类是用于描述图像信息的类
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_BGR);
Graphics g = image.getGraphics();// 产生Image对象的Graphics对象,改对象可以在图像上进行各种绘制操作
g.fillRect(0, 0, width, height);
g.setFont(new Font("Times New Roman", Font.ROMAN_BASELINE, 18));
g.setColor(getRandColor(110, 133));
// 绘制干扰线
for (int i = 0; i <= lineSize; i++) {
drowLine(g);
}
// 绘制随机字符
String randomString = "";
for (int i = 1; i <= stringNum; i++) {
randomString = drowString(g, randomString, i);
}
//将生成的随机字符串保存到session中，而jsp界面通过session.getAttribute("RANDOMCODEKEY")，
//获得生成的验证码，然后跟用户输入的进行比较
session.removeAttribute(RANDOMCODEKEY);
session.setAttribute(RANDOMCODEKEY, randomString);
g.dispose();
try {
// 将内存中的图片通过流动形式输出到客户端
ImageIO.write(image, "JPEG", response.getOutputStream());
} catch (Exception e) {
e.printStackTrace();
}
}
/*
* 绘制字符串
*/
private String drowString(Graphics g, String randomString, int i) {
g.setFont(getFont());
g.setColor(new Color(random.nextInt(101), random.nextInt(111), random
.nextInt(121)));
String rand = String.valueOf(getRandomString(random.nextInt(randString
.length())));
randomString += rand;
g.translate(random.nextInt(3), random.nextInt(3));
g.drawString(rand, 13 * i, 16);
return randomString;
}
/*
* 绘制干扰线
*/
private void drowLine(Graphics g) {
int x = random.nextInt(width);
int y = random.nextInt(height);
int xl = random.nextInt(13);
int yl = random.nextInt(15);
g.drawLine(x, y, x + xl, y + yl);
}
/*
* 获取随机的字符
*/
public String getRandomString(int num) {
return String.valueOf(randString.charAt(num));
}
}
文章出处：https://blog.csdn.net/u012836851/article/details/52368570