java web图形验证码
<!DOCTYPE html> <head> <title>新用户注册</title> <style> #box2{ margin-top:1.5%; } input { border-left:none; } </style> </head> <body> <div class="input-group" id="box2"> <span class="input-group-addon">图形验证码:</span> <input type="tel" class="form-control" placeholder="请输入图形验证码" /> <span><canvas id="canvas" width="120" height="45"></canvas> <a href="#" id="changeImg">看不清,换一张</a></span> </div> <script> /**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+")"; } drawPic(); document.getElementById("changeImg").onclick = function(e){ e.preventDefault(); drawPic(); } /**绘制验证码图片**/ function drawPic(){ var canvas=document.getElementById("canvas"); var width=canvas.width; var height=canvas.height; var ctx = canvas.getContext('2d'); ctx.textBaseline = 'bottom'; /**绘制背景色**/ ctx.fillStyle = randomColor(180,240); //颜色若太深可能导致看不清 ctx.fillRect(0,0,width,height); /**绘制文字**/ var str = 'ABCEFGHJKLMNPQRSTWXY123456789'; for(var i=0; i<4; i++){ var txt = str[randomNum(0,str.length)]; ctx.fillStyle = randomColor(50,160); //随机生成字体颜色 ctx.font = randomNum(15,40)+'px SimHei'; //随机生成字体大小 var x = 10+i*25; var y = randomNum(25,45); var deg = randomNum(-45, 45); //修改坐标原点和旋转角度 ctx.translate(x,y); ctx.rotate(deg*Math.PI/180); ctx.fillText(txt, 0,0); //恢复坐标原点和旋转角度 ctx.rotate(-deg*Math.PI/180); ctx.translate(-x,-y); } /**绘制干扰线**/ for(var i=0; i<8; i++){ ctx.strokeStyle = randomColor(40,180); ctx.beginPath(); ctx.moveTo( randomNum(0,width), randomNum(0,height) ); ctx.lineTo( randomNum(0,width), randomNum(0,height) ); ctx.stroke(); } /**绘制干扰点**/ for(var i=0; i<100; i++){ ctx.fillStyle = randomColor(0,255); ctx.beginPath(); ctx.arc(randomNum(0,width),randomNum(0,height), 1, 0, 2*Math.PI); ctx.fill(); } } </script> </html>