本篇文章给大家分享的是有关php制作验证码的过程，小编觉得挺实用的，因此分享给大家学习，希望大家阅读完这篇文章后可以有所收获，话不多说，跟着小编一起来看看吧。

php使用GD库生成验证码

一、绘图步骤:

1.创建画布，分配颜色,使用以下两个函数(可以在php手册GD库函数中找到)：

imagecreatetruecolor()

imagecolorallocate()

2.绘画过程：

imagefill()

imagettftext()

imagesetpixel()

imageline()

3.输出图像：

header(“Content-Type:image/png”);

imagepng();

imagejpeg();

4.销毁图片（释放内存）

imagedestroy();

二、绘图具体步骤

生成验证码字符串

private function getCode(){ $str="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"; $t=''; for($i=0;$i<$this->m;$i++){ $t.=$str[rand(0,$this->type['letter'])]; } return $t; }

画出验证码

function drawCode(){ $code=$this->getCode();//获取验证码字符串 imagefill($this->im, 0, 0, $this->bg); for ($i=0; $i <200 ; $i++) { imagesetpixel($this->im, rand(0,$this->width), rand(0,$this->height), rand(0,255)); } imageline($this->im, rand(0,$this->width), rand(0,$this->height), rand(0,$this->width), rand(0,$this->height), rand(0,255)); $c=imagecolorallocate($this->im, rand(0,200), rand(0,200), rand(0,200)); for($i=0;$i<$this->m;$i++){ imagettftext($this->im, 18, rand(-40,40), 8+(18*$i), 24, $c, "georgia.ttf",$code[$i] ); } }

输出图像

function printImage(){ $this->drawCode(); header("Content-Type:image/jpeg"); imagepng($this->im); $this->destroy(); } function destroy(){ imagedestroy($this->im); }

三、代码演示

<?php/*** 验证码画图类*/class Image { private $width; private $height; private $im; private $bg; private $m; private $type=array('num' => 9,'letter' => 61 ); function __construct($width,$height,$m) { $this->width=$width; $this->height=$height; $this->m=$m; $this->im=imagecreatetruecolor($this->width, $this->height); $this->bg=imagecolorallocate($this->im, 220, 220, 220); } private function getCode(){ $str="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"; $t=''; for($i=0;$i<$this->m;$i++){ $t.=$str[rand(0,$this->type['letter'])]; } return $t; } function drawCode(){ $code=$this->getCode();//获取验证码字符串 imagefill($this->im, 0, 0, $this->bg); //加干扰点 for ($i=0; $i <200 ; $i++) { imagesetpixel($this->im, rand(0,$this->width), rand(0,$this->height), rand(0,255)); } //加干扰线 imageline($this->im, rand(0,$this->width), rand(0,$this->height), rand(0,$this->width), rand(0,$this->height), rand(0,255)); $c=imagecolorallocate($this->im, rand(0,200), rand(0,200), rand(0,200)); for($i=0;$i<$this->m;$i++){ imagettftext($this->im, 18, rand(-40,40), 8+(18*$i), 24, $c, "georgia.ttf",$code[$i] ); } } function printImage(){ $this->drawCode(); header("Content-Type:image/jpeg"); imagepng($this->im); $this->destroy(); } function destroy(){ imagedestroy($this->im); }}function unit_test(){ $obj=new Image(20*4,30,4); $obj->printImage();}unit_test();?>

以上就是php制作验证码的过程，小编相信有部分知识点可能是我们日常工作会见到或用到的。希望你能通过这篇文章学到更多知识。更多详情敬请关注亿速云行业资讯频道。