JS如何实现图片验证码功能

本篇内容主要讲解"JS如何实现图片验证码功能"，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习"JS如何实现图片验证码功能"吧!

1. html代码

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>    
                
    
           

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[xss_clean] = "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

到此，相信大家对"JS如何实现图片验证码功能"有了更深的了解，不妨来实际操作一番吧！这里是网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！