实现图片验证码类 PHP

Posted 2020-10-03

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封装一个图片验证码类

<?php
class Captcha{
    private $img;
    private $imgX;
    private $imgY;
    private $codeNum;
    private $code;
    private $str="abcdefghjklmnpqrstuvwxyz123456789ABCDEFGHJKLMNPQRSTUVWXYZ";

    public function __construct($imgX=80,$imgY=40,$codeNum=4){
        $this->imgX=$imgX;
        $this->imgY=$imgY;
        $this->codeNum=$codeNum;
    }

    public function printImg(){
        $this->createBg();
        $this->getCode();
        $this->setCode();
        $this->setDot();
        $this->setCurve();
        $this->outImg();
    }
    //创建画布背景图片
    private function createBg(){
        //创建画布
        $this->img=imagecreate($this->imgX,$this->imgY);
        //给图片背景颜色分配
        imagecolorallocate($this->img,243,251,254);
    }


    //输出背景图片
    private function outImg(){
        header("Content-type:image/jpeg");
        imagejpeg($this->img);
    }


    //生成验证码
    private function getCode(){
        //生成验证码
        for($i=0;$i<$this->codeNum;$i++){
            $key=rand(0,strlen($this->str)-1);
            $this->code.=$this->str[$key];
        }
        $this->setSession();
    }

    
    //生成背景图片和文字颜色
    private function setCode(){
        for($i=0;$i<$this->codeNum;$i++){
            $char_color=imagecolorallocate($this->img,rand(0,255),rand(0,255),rand(0,255));
            $font_size=rand(3,5);
            $font_height=imagefontheight($font_size);//根据设置的字体大小获取字体高度
            $x=($this->imgX/$this->codeNum)*$i;//设置验证码每个字的坐标位置
            $y=rand(0,$this->imgY-$font_height-3);
            imagechar($this->img,$font_size,$x,$y,$this->code{$i},$char_color);//把字符串写到图片上  imagechar()
        }

    }



    //画干扰点
    private function setDot(){
        for($i=0;$i<=50;$i++){
            $dot_color=imagecolorallocate($this->img,rand(0,255),rand(0,255),rand(0,255));
            imagesetpixel($this->img,rand(1,80),rand(1,40),$dot_color);//把干扰点写到图片上  imagesetpixel()
        }

    }


    //画干扰线
    private function setCurve(){
        for($i=0;$i<=3;$i++){
            $line_color=imagecolorallocate($this->img,rand(0,255),rand(0,255),rand(0,255));
            imagearc($this->img,rand(1,$this->imgX),rand(1,$this->imgY),100,80,30,15,$line_color);
        }
    }

    //把验证码存储到session
    private function setSession(){
        session_start();
        $_SESSION[‘code‘]=strtolower($this->code);
    }

}

$captcha=new Captcha;
$captcha->printImg();

在外部调用类

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
 <head>
  <title> new document </title>
  <meta name="generator" content="editplus" />
  <meta name="author" content="" />
  <meta name="keywords" content="" />
  <meta name="description" content="" />
  <meta charset="utf-8">
 </head>

 <body>

 <label>请输入验证码：</label><input type="text"><img src="captcha.php" onclick="this.src=‘captcha.php?‘+Math.random()" />
 </body>
</html>

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