Thinkphp3.2实用篇之计算型验证码示例

是不是觉得普通的验证码已经没办法满足，接下来介绍如何将tp现有的验证码改为计算型验证码：

首先找到：ThinkPHP/Library/Think/Verify.class.php

在其中加入以下代码：

public function entry_add($id = '') {    $this->length='3';    // 图片宽(px)    $this->imageW || $this->imageW = $this->length*$this->fontSize*1.5 + $this->length*$this->fontSize/2;     // 图片高(px)    $this->imageH || $this->imageH = $this->fontSize * 2.5;    // 建立一幅 $this->imageW x $this->imageH 的图像    $this->_image = imagecreate($this->imageW, $this->imageH);     // 设置背景       imagecolorallocate($this->_image, $this->bg[0], $this->bg[1], $this->bg[2]);     // 验证码字体随机颜色    $this->_color = imagecolorallocate($this->_image, mt_rand(1,150), mt_rand(1,150), mt_rand(1,150));    // 验证码使用随机字体    $ttfPath = dirname(__FILE__) . '/Verify/' . ($this->useZh ? 'zhttfs' : 'ttfs') . '/';    if(empty($this->fontttf)){      $dir = dir($ttfPath);      $ttfs = array();          while (false !== ($file = $dir->read())) {        if($file[0] != '.' && substr($file, -4) == '.ttf') {          $ttfs[] = $file;        }      }      $dir->close();      $this->fontttf = $ttfs[array_rand($ttfs)];    }     $this->fontttf = $ttfPath . $this->fontttf;        if($this->useImgBg) {      $this->_background();    }        if ($this->useNoise) {      // 绘杂点      $this->_writeNoise();    }    if ($this->useCurve) {      // 绘干扰线      $this->_writeCurve();    }        // 绘验证码    $code = array(); // 验证码    $symbol=array('+','-');    $codeNX = 0; // 验证码第N个字符的左边距    $now_symbol=$symbol[rand(0,1)];    for ($i = 0; $i<$this->length; $i++) {      if($i==1){        $code[$i] = $now_symbol;        $codeNX += mt_rand($this->fontSize*1.2, $this->fontSize*1.6);        imagettftext($this->_image, $this->fontSize,0, $codeNX, $this->fontSize*1.6, $this->_color, $ttfPath.'2.ttf', $code[$i]);      }      else{        $code[$i] = $this->codeSet[mt_rand(0, strlen($this->codeSet)-1)];        $codeNX += mt_rand($this->fontSize*1.2, $this->fontSize*1.6);        imagettftext($this->_image, $this->fontSize, mt_rand(-40, 40), $codeNX, $this->fontSize*1.6, $this->_color, $this->fontttf, $code[$i]);      }     }        // 保存验证码    $key    =  $this->authcode($this->seKey);    $str=implode('', $code);    eval("/$re=$str;");    $code    =  $this->authcode($re);    $secode   =  array();    $secode['verify_code'] = $code; // 把校验码保存到session    $secode['verify_time'] = NOW_TIME; // 验证码创建时间    session($key.$id, $secode);                header('Cache-Control: private, max-age=0, no-store, no-cache, must-revalidate');    header('Cache-Control: post-check=0, pre-check=0', false);        header('Pragma: no-cache');    header("content-type: image/png");    // 输出图像    imagepng($this->_image);    imagedestroy($this->_image);  }