php 驗證碼詳細生成與使用方法

2024-09-04 11:44:28

字體：大中小

來源：轉載

供稿：網友

注意:以下代碼需要打開php的gd庫,修改php.in文件的配置,把已經注釋掉的行之前的分號取消即可:extension=php_gd2.dll.

實例一,代碼如下:

$width = 165;

        $height = 120;

        $image = imagecreatetruecolor($width,$height);

        $bg_color = imagecolorallocate($image,255,255,255);

        $tm = imagecolorallocate($image,255,0,0);

        imagefilledrectangle($image,0,0,$width,$height,$bg_color);

        imagefill($image,0,0,$bg_color);

        /*

        //$text = random_text(5);

        $text = "ffff";

        $font = 8;

        $struft=iconv("gbk","utf-8",$text);

        $x = imagesx($image);

        $y = imagesy($image);

        $fg_color = imagecolorallocate($image,233,14,91);

        imagestring($image,$font,$x,$y,$struft,$fg_color);

        $_session['captcha'] = $text;

        */

header("content-type:image/png");

        imagepng($image);

        imagedestroy($image);

實例二,代碼如下:validate.php

采用了session識別,稍微改進了一下目前網絡上流傳的php驗證碼,加入雜點,數字顏色隨機顯示,控制4位數字顯示.

<?php

session_start();

//生成驗證碼圖片

header("content-type: image/png");

$im = imagecreate(44,18);

$back = imagecolorallocate($im, 245,245,245);

imagefill($im,0,0,$back); //背景

srand((double)microtime()*1000000);

//生成4位數字

for($i=0;$i<4;$i++){

$font = imagecolorallocate($im, rand(100,255),rand(0,100),rand(100,255));

$authnum=rand(1,9);

$vcodes.=$authnum;

imagestring($im, 5, 2+$i*10, 1, $authnum, $font);

}

for($i=0;$i<100;$i++) //加入干擾象素

{ //開源代碼Vevb.com

$randcolor = imagecolorallocate($im,rand(0,255),rand(0,255),rand(0,255));

imagesetpixel($im, rand()%70 , rand()%30 , $randcolor);

}

imagepng($im);

imagedestroy($im);

$_session['vcode'] = $vcodes;

?>

下面看完整實例,代碼如下:

<?php

    @header("content-type:text/html; charset=utf-8");

    //打開session

    session_start();

?>

<html>

    <head>

       <meta http-equiv="content-type" content="text/html; charset=utf-8" />

       <title>php驗證碼示例</title>

    </head>

    <body>

       驗證碼：<br/>

       <iframe id="iimg" height="100" width=300 src="img.php" frameborder="0" ></iframe>

       <br/>

       <input type=button value="看不清，換一張" onclick="iimg.location.reload();">

       <br>

       <form action="validate.php" method="post">

           輸入驗證碼：<input name="imgid" style="width:60">

           <input type="submit" value="確定">

       </form>

    </body>

</html>

php判斷用戶輸入的驗證碼是否與系統生成的一致,代碼如下:

<?php @header("content-type:text/html; charset=utf-8");

    //開啟session

    session_start();

    //得到用戶輸入的驗證碼，并轉換成大寫

    $imgid_req = $_request['imgid'];

    $imgid_req = strtoupper($imgid_req);

    //驗證該字符串是否注冊了session變量

    if (session_is_registered($imgid_req)) {

       echo "<font color=blue >通過驗證！</font>";

    } else {

       echo "<font color=red >驗證錯誤！</font>";

    }

    //關閉session，以清除所有注冊過的變量

    session_destroy();

?>