php 验证码详细生成与使用方法

2024-09-04 11:44:28

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来源：转载

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注意:以下代码需要打开php的gd库,修改php.in文件的配置,把已经注释掉的行之前的分号取消即可:extension=php_gd2.dll.

实例一,代码如下:

$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);

实例二,代码如下:validate.php

采用了session识别,稍微改进了一下目前网络上流传的php验证码,加入杂点,数字颜色随机显示,控制4位数字显示.

<?php

session_start();

//生成验证码图片

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位数字

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++) //加入干扰象素

{ //开源代码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;

?>

下面看完整实例,代码如下:

<?php

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

    //打开session

    session_start();

?>

<html>

    <head>

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

       <title>php验证码示例</title>

    </head>

    <body>

       验证码：<br/>

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

       <br/>

       <input type=button value="看不清，换一张" onclick="iimg.location.reload();">

       <br>

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

           输入验证码：<input name="imgid" style="width:60">

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

       </form>

    </body>

</html>

php判断用户输入的验证码是否与系统生成的一致,代码如下:

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

    //开启session

    session_start();

    //得到用户输入的验证码，并转换成大写

    $imgid_req = $_request['imgid'];

    $imgid_req = strtoupper($imgid_req);

    //验证该字符串是否注册了session变量

    if (session_is_registered($imgid_req)) {

       echo "<font color=blue >通过验证！</font>";

    } else {

       echo "<font color=red >验证错误！</font>";

    }

    //关闭session，以清除所有注册过的变量

    session_destroy();

?>