<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title>T65-验证码</title>
<style>
#mycanvas{
cursor: pointer;
}
</style>
</head>
<body>
<canvas id="mycanvas" width='90' height='40'>
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</canvas>
</body>
<script type="text/javascript">
/*生成4位随机数*/
function rand(){
var str="abcdefghijklmnopqrstuvwxyz0123456789";
var arr=str.split("");
var validate="";
var ranNum;
for(var i=0;i<4;i++){
ranNum=Math.floor(Math.random()*36); //随机数在[0,35]之间
validate+=arr[ranNum];
}
return validate;
}
/*干扰线的随机x坐标值*/
function lineX(){
var ranLineX=Math.floor(Math.random()*90);
return ranLineX;
}
/*干扰线的随机y坐标值*/
function lineY(){
var ranLineY=Math.floor(Math.random()*40);
return ranLineY;
}
function clickChange(){
var mycanvas=document.getElementById('mycanvas');
var cxt=mycanvas.getContext('2d');
cxt.fillStyle='#000';
cxt.fillRect(0,0,90,40);
/*生成干扰线20条*/
for(var j=0;j<20;j++){
cxt.strokeStyle='#fff';
cxt.beginPath(); //若省略beginPath，则每点击一次验证码会累积干扰线的条数
cxt.moveTo(lineX(),lineY());
cxt.lineTo(lineX(),lineY());
cxt.lineWidth=0.5;
cxt.closePath();
cxt.stroke();
}
cxt.fillStyle='red';
cxt.font='bold 20px Arial';
cxt.fillText(rand(),25,25); //把rand()生成的随机数文本填充到canvas中
}
clickChange();
/*点击验证码更换*/
mycanvas.onclick=function(e){
e.preventDefault(); //阻止鼠标点击发生默认的行为
clickChange();
};
</script>
</html>