html验证码 - 云昭写意

html验证码
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
    <input type="text" value="" placeholder="请输入验证码（区分大小写）"
          style="height:43px;position: relative; top:-15px; font-size:20px;" id="text">
        <canvas id="canvas" width="100" height="43" onclick="dj()" style="border: 1px solid #ccc;
                       border-radius: 5px;"></canvas>
        <button class="btn" onclick="sublim()">提交</button>


</body>
<script type="text/javascript">
var show_num = [];
  draw(show_num);
  function dj() {
    draw(show_num);
  }
  function sublim() {
    var val = document.getElementById("text").value;
    var num = show_num.join("");
    if (val == '') {
      alert('请输入验证码！');
    } else if (val == num) {
      alert('提交成功！');
      document.getElementById(".input-val").val('');
      draw(show_num);

    } else {
      alert('验证码错误！\n你输入的是:  ' + val + "\n正确的是:  " + num + '\n请重新输入！');
      document.getElementById("text").value = '';
      draw(show_num);
    }



  }
  function draw(show_num) {
    var canvas_width = document.getElementById('canvas').clientWidth;
    var canvas_height = document.getElementById('canvas').clientHeight;
    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,q,w,e,r,t,y,u,i,o,p,a,s,d,f,g,h,j,k,l,z,x,c,v,b,n,m";
    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;
      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>
posted on 2022-01-08 21:31 云昭写意阅读(138) 评论(0) 编辑收藏举报