<!DOCTYPE html>
<html>
<!-- head -->
<head>
<meta charset="utf-8">
<title>图片登录验证</title>
<meta name="renderer" content="webkit">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
<style>
body{margin: 10px;}
.demo-carousel{height: 200px; line-height: 200px; text-align: center;}
.code {
width: 400px;
margin: 0 auto;
}
.input-val {
width: 295px;
background: #ffffff;
height: 2.8rem;
padding: 0 2%;
border-radius: 5px;
border: none;
border: 1px solid rgba(0,0,0,.2);
font-size: 1.0625rem;
}
#canvas {
float: right;
display: inline-block;
border: 1px solid #ccc;
border-radius: 5px;
cursor: pointer;
}
.btn {
width: 100px;
height: 40px;
background: #f1f1f1;
border: 1px solid #ccc;
border-radius: 5px;
margin: 20px auto 0;
display: block;
font-size: 1.2rem;
color: #e22e1c;
cursor: pointer;
}
* {
margin: 0;
padding: 0;
box-sizing: border-box;
}
</style>
</head>
<script src="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script>
<body cz-shortcut-listen="true" class="layui-layout-body">
<div class="layui-layer-move">
<div class="code">
<input type="text" value="" placeholder="请输入验证码（不区分大小写）" class="input-val">
<canvas id="canvas" width="100" height="43"></canvas>
<button class="btn">提交</button>
</div>
</div>
</body>
<script>
$(function(){
var show_num = [];
draw(show_num);
$("#canvas").on('click',function(){
draw(show_num);
})
$(".btn").on('click',function(){
var val = $(".input-val").val().toLowerCase();
var num = show_num.join("");
if(val==''){
alert('请输入验证码！');
}else if(val == num){
alert('提交成功！');
$(".input-val").val('');
draw(show_num);
}else{
alert('验证码错误！请重新输入！');
$(".input-val").val('');
draw(show_num);
}
})
})
function draw(show_num) {
var canvas_width=$('#canvas').width();
var canvas_height=$('#canvas').height();
var canvas = document.getElementById("canvas");//获取到canvas的对象，演员
var context = canvas.getContext("2d");//获取到canvas画图的环境，演员表演的舞台
canvas.width = canvas_width;
canvas.height = canvas_height;
var sCode = "A,B,C,E,F,G,H,J,K,L,M,N,P,Q,R,S,T,W,X,Y,Z,1,2,3,4,5,6,7,8,9,0";
var aCode = sCode.split(",");
var aLength = aCode.length;//获取到数组的长度
for (var i = 0; i <= 3; i++) {
var j = Math.floor(Math.random() * aLength);//获取到随机的索引值
var deg = Math.random() * 30 * Math.PI / 180;//产生0~30之间的随机弧度
var txt = aCode[j];//得到随机的一个内容
show_num[i] = txt.toLowerCase();
var x = 10 + i * 20;//文字在canvas上的x坐标
var y = 20 + Math.random() * 8;//文字在canvas上的y坐标
context.font = "bold 23px 微软雅黑";
context.translate(x, y);
context.rotate(deg);
context.fillStyle = randomColor();
context.fillText(txt, 0, 0);
context.rotate(-deg);
context.translate(-x, -y);
}
for (var i = 0; i <= 5; i++) { //验证码上显示线条
context.strokeStyle = randomColor();
context.beginPath();
context.moveTo(Math.random() * canvas_width, Math.random() * canvas_height);
context.lineTo(Math.random() * canvas_width, Math.random() * canvas_height);
context.stroke();
}
for (var i = 0; i <= 30; i++) { //验证码上显示小点
context.strokeStyle = randomColor();
context.beginPath();
var x = Math.random() * canvas_width;
var y = Math.random() * canvas_height;
context.moveTo(x, y);
context.lineTo(x + 1, y + 1);
context.stroke();
}
}
function randomColor() {//得到随机的颜色值
var r = Math.floor(Math.random() * 256);
var g = Math.floor(Math.random() * 256);
var b = Math.floor(Math.random() * 256);
return "rgb(" + r + "," + g + "," + b + ")";
}
</script>
</html>也可以实用后端验证方式
https://blog.csdn.net/datuo/article/details/1393227
https://blog.csdn.net/rchm8519/article/details/45081225
package com.hikvision.cms.module.cpi.servlet;
import java.awt.Color;
import java.awt.Container;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.util.Random;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
public class ImageTool {
public String sRand = "";
public Color getRandColor(int fc, int bc)
{//给定范围获得随机颜色
Random random = new Random();
if (fc > 255)
fc = 255;
if (bc > 255)
bc = 255;
int r = fc + random.nextInt(bc - fc);
int g = fc + random.nextInt(bc - fc);
int b = fc + random.nextInt(bc - fc);
return new Color(r, g, b);
}
public BufferedImage creatImage()
{//在内存中创建图像
int width = 60;
int height = 20;
BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
//获取图形上下文
Graphics g = image.getGraphics();
//生成随机类
Random random = new Random();
//设定背景色
g.setColor(getRandColor(200,250));
g.fillRect(0, 0, width, height);
//设定字体
g.setFont(new Font("Times New Roman",Font.PLAIN,18));
//画边框
// g.setColor(new Color());
// g.drawRect(0, 0, width-1, height-1);
//随机产生155条干扰经，使图像中的认证码不易被其他程序探测到
for(int i=0; i<155; i++)
{
g.setColor(getRandColor(160,200));
int x = random.nextInt(width);
int y = random.nextInt(height);
int x1 = random.nextInt(12);
int y1 = random.nextInt(12);
g.drawLine(x, y, x+x1, y+y1);
}
//取随机产生 的认证码（4位数字）
sRand = "";
for(int i=0; i<4; i++)
{
String rand = String .valueOf(random.nextInt(10));
sRand+=rand;
//将认证码显示到图像中
g.setColor(new Color(20+random.nextInt(110), 20 + random.nextInt(110), 20+random.nextInt(110)));
//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
g.drawString(rand, 13*i+6, 16);
}
//图像生效
g.dispose();
return image;
}
public String getRand()
{
return sRand;
}
public static void main(String[] args)
{
ImageTool it = new ImageTool();
JFrame jf = new JFrame();
jf.setSize(200,300);
jf.setTitle("产生验证码");
Container ct = jf.getContentPane();
ImageIcon ii = new ImageIcon(it.creatImage());
JLabel jl = new JLabel(ii);
ct.add(jl);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf.setVisible(true);
System.out.println(it.getRand());
}
}
来源：oschina
链接：https://my.oschina.net/u/4399667/blog/3985398