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How to automatically generate verification code in php

王林Original: 2021-10-21 16:41:383055browse

php method to automatically generate verification codes: [session_start(); $width = 150; $height = 40; $image = imagecreatetruecolor($width, $height);$bgcol...].

The operating environment of this article: windows10 system, php 7, thinkpad t480 computer.

Nowadays, verification codes are used more and more in forms, but it is always inconvenient to implement it with js, so I use php to implement it and record it here.

Of course, we can also encapsulate it into a function, which is very convenient for future use. It is not encapsulated here, and interested friends can encapsulate it by themselves.

Specific implementation code:

Create a new cap_sz.php file:

<?php
session_start(); //设置session,一定要在顶部

$width = 150; //设置图片宽为300像素
$height = 40; //设置图片高为40像素

$image = imagecreatetruecolor($width, $height); //设置验证码大小的函数
$bgcolor = imagecolorallocate($image, 255, 255, 255); //验证码颜色RGB为(255,255,255)#ffffff
imagefill($image, 0, 0, $bgcolor); //区域填充

$cap_code = "";
for($i=0;$i<4;$i++){
    $fontsize = 7; //设置字体大小
    $fontcolor = imagecolorallocate($image, rand(0,120), rand(0,120), rand(0,120));
    //数字越大，颜色越浅，这里是深颜色0-120
    $fontcontent = rand(0,9);
    $cap_code.=$fontcontent; //.=连续定义变量
   
    $x = ($i*150/4)+rand(5,10);
    $y = rand(5,10);
    //设置坐标
   
    imagestring($image, $fontsize, $x, $y, $fontcontent, $fontcolor);
}

$_SESSION[&#39;code&#39;] = $cap_code; //存到session

//设置干扰元素，设置雪花点
for($i=0;$i<300;$i++){
    $inputcolor = imagecolorallocate($image, rand(50,200), rand(20,200), rand(50,200));
    //设置颜色，20-200颜色比数字浅，不干扰阅读
    imagesetpixel($image, rand(1,149), rand(1,39), $inputcolor);
    //画一个单一像素的元素
}

//增加干扰元素，设置横线(先设置线的颜色，在设置横线)
for ($i=0;$i<4;$i++) {
    $linecolor = imagecolorallocate($image, rand(20,220), rand(20,220),rand(20,220));
    //设置线的颜色

    imageline($image, rand(1,149), rand(1,39), rand(1,299), rand(1,149), $linecolor);  

}

//因为有些浏览器，访问的content-type会是文本型（乱码），所以我们需要设置成图片的格式类型
header(&#39;Content-Type:image/png&#39;);

imagepng($image); //建立png函数
imagedestroy($image); //结束图形函数，消除$image

Then create a new index.php for verification

<?php
header("Content-Type: text/html;charset=utf-8");
if (isset($_REQUEST[&#39;code&#39;])){
    session_start();

    if ($_REQUEST[&#39;code&#39;] == $_SESSION[&#39;code&#39;]){
        echo "输入正确";
    }else{
        echo "输入错误，请重新输入";
    }

    exit();
}

?>

<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> //这里不能少，不然乱码
    <title>验证码测试</title>
</head>
<body>
<form>
<p>验证码:<img src="cap_sz.php" onClick="this.src=&#39;cap_sz.php?nocache=&#39;+Math.random()" style="cursor:hand" alt="点击换一张"/>点击图片可更换验证码</p>
<p>请输入图片中的内容:<input type="text" name="code" value=""/></p>
<p><input type="submit" width="20px" height=19px value="提交"></input></p>

</form>
</body>
</html>

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