效果图如下：
<canvas id="canvas1" style="margin-left: 200px;"></canvas><br /> <button id="btnRefresh" style="position: relative;left: 200px;">看不清，刷新一下</button> <script> /*定义函数生成随机颜色*/ function colorRandom(){ 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+")"; } /*生成随机数*/ var canvas,context; function getYZ(){ canvas = document.getElementById("canvas1"); context = canvas.getContext('2d'); canvas.width = 200; canvas.height = 100; context.beginPath(); context.fillStyle = colorRandom();//显示验证码区域的背景色 context.rect(0,55,100,40); context.fill(); for(var i = 0;i<4;i++){ context.font =( Math.random()*20+16)+"px 微软雅黑";//数字随机大小 context.fillStyle = colorRandom();//数字颜色 context.fillText(parseInt(Math.random()*9), 20*i,90); //0-9的随机数 } } /*实现*/ window.onload = function(){ getYZ(); document.getElementById("btnRefresh").onclick = function(){ getYZ(); } } </script> <!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>图形验证码</title> </head> <body> <div id="v_container" style=" 200px;height: 50px;"></div> <input type="text" id="code_input" value="" placeholder="请输入验证码"/><button id="my_button">验证</button> </body> <script> !(function(window, document) { function GVerify(options) { //创建一个图形验证码对象，接收options对象为参数 this.options = { //默认options参数值 id: "", //容器Id canvasId: "verifyCanvas", //canvas的ID "100", //默认canvas宽度 height: "30", //默认canvas高度 type: "blend", //图形验证码默认类型blend:数字字母混合类型、number:纯数字、letter:纯字母 code: "" } if(Object.prototype.toString.call(options) == "[object Object]"){//判断传入参数类型 for(var i in options) { //根据传入的参数，修改默认参数值 this.options[i] = options[i]; } }else{ this.options.id = options; } this.options.numArr = "0,1,2,3,4,5,6,7,8,9".split(","); this.options.letterArr = getAllLetter(); this._init(); this.refresh(); } GVerify.prototype = { /**版本号**/ version: '1.0.0', /**初始化方法**/ _init: function() { var con = document.getElementById(this.options.id); var canvas = document.createElement("canvas"); this.options.width = con.offsetWidth > 0 ? con.offsetWidth : "100"; this.options.height = con.offsetHeight > 0 ? con.offsetHeight : "30"; canvas.id = this.options.canvasId; canvas.width = this.options.width; canvas.height = this.options.height; canvas.style.cursor = "pointer"; canvas.innerHTML = "您的浏览器版本不支持canvas"; con.appendChild(canvas); var parent = this; canvas.onclick = function(){ parent.refresh(); } }, /**生成验证码**/ refresh: function() { this.options.code = ""; var canvas = document.getElementById(this.options.canvasId); if(canvas.getContext) { var ctx = canvas.getContext('2d'); }else{ return; } ctx.textBaseline = "middle"; ctx.fillStyle = randomColor(180, 240); ctx.fillRect(0, 0, this.options.width, this.options.height); if(this.options.type == "blend") { //判断验证码类型 var txtArr = this.options.numArr.concat(this.options.letterArr); } else if(this.options.type == "number") { var txtArr = this.options.numArr; } else { var txtArr = this.options.letterArr; } for(var i = 1; i <= 4; i++) { var txt = txtArr[randomNum(0, txtArr.length)]; this.options.code += txt; ctx.font = randomNum(this.options.height/2, this.options.height) + 'px SimHei'; //随机生成字体大小 ctx.fillStyle = randomColor(50, 160); //随机生成字体颜色 ctx.shadowOffsetX = randomNum(-3, 3); ctx.shadowOffsetY = randomNum(-3, 3); ctx.shadowBlur = randomNum(-3, 3); ctx.shadowColor = "rgba(0, 0, 0, 0.3)"; var x = this.options.width / 5 * i; var y = this.options.height / 2; var deg = randomNum(-30, 30); /**设置旋转角度和坐标原点**/ ctx.translate(x, y); ctx.rotate(deg * Math.PI / 180); ctx.fillText(txt, 0, 0); /**恢复旋转角度和坐标原点**/ ctx.rotate(-deg * Math.PI / 180); ctx.translate(-x, -y); } /**绘制干扰线**/ for(var i = 0; i < 4; i++) { ctx.strokeStyle = randomColor(40, 180); ctx.beginPath(); ctx.moveTo(randomNum(0, this.options.width), randomNum(0, this.options.height)); ctx.lineTo(randomNum(0, this.options.width), randomNum(0, this.options.height)); ctx.stroke(); } /**绘制干扰点**/ for(var i = 0; i < this.options.width/4; i++) { ctx.fillStyle = randomColor(0, 255); ctx.beginPath(); ctx.arc(randomNum(0, this.options.width), randomNum(0, this.options.height), 1, 0, 2 * Math.PI); ctx.fill(); } }, /**验证验证码**/ validate: function(code){ var code = code.toLowerCase(); var v_code = this.options.code.toLowerCase(); console.log(v_code); if(code == v_code){ return true; }else{ this.refresh(); return false; } } } /**生成字母数组**/ function getAllLetter() { var letterStr = "a,b,c,d,e,f,g,h,i,j,k,l,m,n,p,q,r,s,t,u,v,w,x,y,z,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"; return letterStr.split(","); } /**生成一个随机数**/ function randomNum(min, max) { return Math.floor(Math.random() * (max - min) + min); } /**生成一个随机色**/ function randomColor(min, max) { var r = randomNum(min, max); var g = randomNum(min, max); var b = randomNum(min, max); return "rgb(" + r + "," + g + "," + b + ")"; } window.GVerify = GVerify; })(window, document); </script> <script> var verifyCode = new GVerify("v_container"); document.getElementById("my_button").onclick = function(){ var res = verifyCode.validate(document.getElementById("code_input").value); if(res){ alert("验证正确"); }else{ alert("验证码错误"); } } </script> </html>