没有GD库也可以用图形验证码（限数字加字母）

最新推荐文章于 2022-10-17 10:26:11 发布

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#图形 #function #header #im #session #服务器

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本文介绍了一种在服务器未安装GD2库的情况下生成图形验证码的方法。通过判断GD库的存在与否来选择不同的生成方式，当GD2存在时使用PNG格式输出，不存在时则采用位图格式，并详细展示了相应的PHP代码。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

服务器由于重新编辑了PHP，漏掉了GD2的安装，图形验证码全部失效，只好搞过另一个图形验证码程序。
下面只提供生成图片的代码：

<?php

* Filename: ck.php

* Author: flashlm

* Update: 07-06-18

session_start();

$auth_num="";

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

$auth_num_k=md5(rand(0,9999));

$auth_num=substr($auth_num_k,10,4);

session_register('auth_num');

//判断是否安装了GD2，如果装了

if(function_exists('imagecreate') && function_exists('imagecolorallocate') && function_exists('imagepng') &&

function_exists('imagesetpixel') && function_exists('imageString') && function_exists('imagedestroy') && function_exists('imagefilledrectangle') && function_exists('imagerectangle')){

Header("Content-type:image/PNG");

$im=imagecreate(63,20);

$black=ImageColorAllocate($im,255,255,255);

$white=ImageColorAllocate($im,255,255,255);

$gray=ImageColorAllocate($im,20,20,20);

//ImageFill($im,63,20,$black);//这行不知道为什么在我公司的服务器上出错误，换个空间ok

imagestring($im,5,10,3,$auth_num,$gray);

for($i=0;$i<200;$i++)

{

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

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

}

ImagePNG($im);

ImageDestroy($im);

}else{//如果没有安装GD2

//禁止缓存

header("Pragma:no-cache");

header("Cache-control:no-cache");

header("ContentType: Image/BMP");

$Color[0] = chr(0).chr(0).chr(0);

$Color[1] = chr(255).chr(255).chr(255);

//0-9,a-z字符的数据

$_Num[0] = "1110000111110111101111011110111101001011110100101111010010111101001011110111101111011110111110000111";

$_Num[1] = "1111011111110001111111110111111111011111111101111111110111111111011111111101111111110111111100000111";

$_Num[2] = "1110000111110111101111011110111111111011111111011111111011111111011111111011111111011110111100000011";

$_Num[3] = "1110000111110111101111011110111111110111111100111111111101111111111011110111101111011110111110000111";

$_Num[4] = "1111101111111110111111110011111110101111110110111111011011111100000011111110111111111011111111000011";

$_Num[5] = "1100000011110111111111011111111101000111110011101111111110111111111011110111101111011110111110000111";

$_Num[6] = "1111000111111011101111011111111101111111110100011111001110111101111011110111101111011110111110000111";

$_Num[7] = "1100000011110111011111011101111111101111111110111111110111111111011111111101111111110111111111011111";

$_Num[8] = "1110000111110111101111011110111101111011111000011111101101111101111011110111101111011110111110000111";

$_Num[9] = "1110001111110111011111011110111101111011110111001111100010111111111011111111101111011101111110001111";

$_Num[10] = "1111011111111101111111101011111110101111111010111111101011111100000111110111011111011101111000100011";

$_Num[11] = "1000000111110111101111011110111101110111110000111111011101111101111011110111101111011110111000000111";

$_Num[12] = "1110000011110111101110111110111011111111101111111110111111111011111111101111101111011101111110001111";

$_Num[13] = "1000001111110111011111011110111101111011110111101111011110111101111011110111101111011101111000001111";

$_Num[14] = "1000000111110111101111011011111101101111110000111111011011111101101111110111111111011110111000000111";

$_Num[15] = "1000000111110111101111011011111101101111110000111111011011111101101111110111111111011111111000111111";

$_Num[16] = "1110000111110111011110111101111011111111101111111110111111111011100011101111011111011101111110001111";

$_Num[17] = "1000100011110111011111011101111101110111110000011111011101111101110111110111011111011101111000100011";

$_Num[18] = "1100000111111101111111110111111111011111111101111111110111111111011111111101111111110111111100000111";

$_Num[19] = "1110000011111110111111111011111111101111111110111111111011111111101111111110111110111011111000011111";

$_Num[20] = "1000100011110111011111011011111101011111110001111111010111111101101111110110111111011101111000100011";

$_Num[21] = "1000111111110111111111011111111101111111110111111111011111111101111111110111111111011110111000000011";

$_Num[22] = "1000100011110010011111001001111100100111110101011111010101111101010111110101011111010101111001010011";

$_Num[23] = "1000100011110011011111001101111101010111110101011111010101111101100111110110011111011001111000110111";

$_Num[24] = "1110001111110111011110111110111011111011101111101110111110111011111011101111101111011101111110001111";

$_Num[25] = "1000000111110111101111011110111101111011110000011111011111111101111111110111111111011111111000111111";

$_Num[26] = "1110001111110111011110111110111011111011101111101110111110111011111011101001101111011001111110001011";

$_Num[27] = "1000001111110111011111011101111101110111110000111111010111111101101111110110111111011101111000110011";

$_Num[28] = "1110000011110111101111011110111101111111111001111111111001111111111011110111101111011110111100000111";

$_Num[29] = "1000000011101101101111110111111111011111111101111111110111111111011111111101111111110111111110001111";

$_Num[30] = "1000100011110111011111011101111101110111110111011111011101111101110111110111011111011101111110001111";

$_Num[31] = "1000100011110111011111011101111101110111111010111111101011111110101111111010111111110111111111011111";

$_Num[32] = "1001010011110101011111010101111101010111110101011111001001111110101111111010111111101011111110101111";

$_Num[33] = "1000100011110111011111101011111110101111111101111111110111111110101111111010111111011101111000100011";

$_Num[34] = "1000100011110111011111011101111110101111111010111111110111111111011111111101111111110111111110001111";

$_Num[35] = "1100000011110111011111111101111111101111111110111111110111111111011111111011111111101110111100000011";

//输出图像文件头

echo chr(66).chr(77).chr(230).chr(4).chr(0).chr(0).chr(0).chr(0).chr(0).chr(0).chr(54).chr(0).chr(0).chr(0).chr(40).chr(0).chr(0).chr(0).chr(40).chr(0).chr(0).chr(0).chr(10).chr(0).chr(0).chr(0).chr(1).chr(0);

//输出图像信息头

echo chr(24).chr(0).chr(0).chr(0).chr(0).chr(0).chr(176).chr(4).chr(0).chr(0).chr(18).chr(11).chr(0).chr(0).chr(18).chr(11).chr(0).chr(0).chr(0).chr(0).chr(0).chr(0).chr(0).chr(0).chr(0).chr(0);