JS 实现图片验证码功能-蒲公英云

JS 实现图片验证码功能

1 HTML代码

<div style="margin: 0px auto 20px auto;width: 240px;">
    <input type="text" id="verify" style="margin: 10px 0px;width: 100px;height:26px;margin-left:5px;display: inline-block;float: left;">
    <canvas width="100" height="34" id="verifyCanvas" style="display: none;"></canvas>
    <img width="100" height="34" id="code_img" style="margin: 10px 10px;" onclick="imgRefresh('verifyCanvas','code_img','verify')">
</div>

2 JS代码

var nums = ["1", "2", "3", "4", "5", "6", "7", "8", "9", "0", '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'];
//绘制验证码
var currentVerifyCode="";
function drawVerificationCode(canvasId,codeImgId){
    var canvas = document.getElementById(canvasId);  //获取HTML端画布
    var context = canvas.getContext("2d");                 //获取画布2D上下文
    context.fillStyle = "cornflowerblue";                  //画布填充色
    context.fillRect(0, 0, canvas.width, canvas.height);   //清空画布
    context.fillStyle = "white";                           //设置字体颜色
    context.font = "25px Arial";                           //设置字体
    var rand = new Array();
    var x = new Array();
    var y = new Array();
    currentVerifyCode="";
    for (var i = 0; i < 5; i++) {
        rand[i] = nums[Math.floor(Math.random() * nums.length)]
        x[i] = i * 16 + 10;
        y[i] = Math.random() * 20 + 20;
        context.fillText(rand[i], x[i], y[i]);
        currentVerifyCode+=rand[i];
    }
    //画3条随机线
    for (var i = 0; i < 3; i++) {
        drawline(canvas, context);
    }
    // 画30个随机点
    for (var i = 0; i < 30; i++) {
        drawDot(canvas, context);
    }
    convertCanvasToImage(canvasId,codeImgId,canvas);
}
// 随机线
function drawline(canvas, context) {
    context.moveTo(Math.floor(Math.random() * canvas.width), Math.floor(Math.random() * canvas.height));             //随机线的起点x坐标是画布x坐标0位置，y坐标是画布高度的随机数
    context.lineTo(Math.floor(Math.random() * canvas.width), Math.floor(Math.random() * canvas.height));  //随机线的终点x坐标是画布宽度，y坐标是画布高度的随机数
    context.lineWidth = 0.5;                                                  //随机线宽
    context.strokeStyle = 'rgba(50,50,50,0.3)';                               //随机线描边属性
    context.stroke();                                                         //描边，即起点描到终点
}
// 随机点(所谓画点其实就是画1px像素的线，方法不再赘述)
function drawDot(canvas, context) {
    var px = Math.floor(Math.random() * canvas.width);
    var py = Math.floor(Math.random() * canvas.height);
    context.moveTo(px, py);
    context.lineTo(px + 1, py + 1);
    context.lineWidth = 0.2;
    context.stroke();
}
// 绘制图片
function convertCanvasToImage(canvasId,codeImgId,canvas) {
    document.getElementById(canvasId).style.display = "none";
    var image = document.getElementById(codeImgId);
    image.src = canvas.toDataURL("image/png");
    return image;
}
// 点击图片刷新
function imgRefresh(canvasId,codeImgId,verifyTextId){
    $('#'+canvasId).remove();
    $('#'+verifyTextId).after('<canvas width="100" height="40" id="'+canvasId+'"></canvas>')
    drawVerificationCode(canvasId,codeImgId);
}
function getCurrentVerifyCode(){
    return currentVerifyCode;
}
$(function(){
    imgRefresh('verifyCanvas','code_img','verify');
})