JS如何编程一个图片验证码的功能效果

本文实例为大家分享了js实现图片验证码功能的具体代码，供大家参考，具体内容如下

以下代码可以直接copy运行，不需要引入jquery.jar

1. html代码

%@ page language="java" contenttype="text/html;
     charset=utf-8" pageencoding="utf-8"%>
    
html>
    
head>
    
meta http-equiv="content-type" content="text/html;
     charset=utf-8">
    
script src="%=request.getcontextpath()%>
    /js/gverify.js">
    /script>
    
style type="text/css">

body, html {
    
 width: 100%;
    
 text-align: center;

}

#picyzm {
    
 width: 100px;
    
 height: 40px;
    
 display: inline-block;
    
 margin: 0 30px;

}

#verifycodedemo {
    
 width: 100%;
    
 display: flex;
    
 margin-top: 200px;
    
 justify-content: center;

}

#btn {
    
 margin: 30px auto;
    
 background-color: blue;
    
 color: #fff;
    
 border-radius: 5px;
    
 border: 0;
    
 width: 100px;
    
 height: 40px;

}
    
/style>
    
/head>
    
body>
    
 div id="verifycodedemo">
    
  input type="text" id="code_input" placeholder="在这个框里输入验证码">
    
  p id="picyzm">
    /p>
    
 /div>
    
 input type="button" value="验证" id="btn">
    
 
 script type="text/javascript">

  //初始化验证码
  var verifycode = new gverify({

   id : "picyzm",
   type : "blend"
  }
    );
    
  //点击按钮验证
  var code = document.getelementbyid("code_input");
    
  var btn = document.getelementbyid("btn");

  btn.onclick = function() {
    
   var res = verifycode.validate(code.value);

   if (res) {
    
    alert("验证通过");

   }
 else {
    
    alert("验证码错误");

   }

  }
    
 /script>
    
/body>
    
/html>

2. 引入gverify.js

!(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
      width: "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();

      if(code == v_code){
    
        return true;

      }
else{
    
        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,o,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);
    

3. 效果图

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