<?php
 class ValidationCode {
  private $width;
  private $height;
  private $codeNum;
  private $image;   //圖像資源
  private $disturbColorNum;
  private $checkCode;
  function __construct($width=80, $height=20, $codeNum=4){
   $this->width=$width;
   $this->height=$height;
   $this->codeNum=$codeNum;
   $this->checkCode=$this->createCheckCode();
   $number=floor($width*$height/15);

   if($number > 240-$codeNum){
    $this->disturbColorNum= 240-$codeNum;
   }else{
    $this->disturbColorNum=$number;
   }

  }
  //通過訪問該方法向瀏覽器中輸出圖像
  function showImage($fontFace=""){
   //第一步：創(chuàng)建圖像背景
   $this->createImage();
   //第二步：設(shè)置干擾元素
   $this->setDisturbColor();
   //第三步：向圖像中隨機畫出文本
   $this->outputText($fontFace);
   //第四步：輸出圖像
   $this->outputImage();
  }

  //通過調(diào)用該方法獲取隨機創(chuàng)建的驗證碼字符串
  function getCheckCode(){
   return $this->checkCode;
  }
  private function createImage(){
   //創(chuàng)建圖像資源
   $this->image=imagecreatetruecolor($this->width, $this->height);
   //隨機背景色
   $backColor=imagecolorallocate($this->image, rand(225, 255), rand(225,255), rand(225, 255));
   //為背景添充顏色
   imagefill($this->image, 0, 0, $backColor);
   //設(shè)置邊框顏色
   $border=imagecolorallocate($this->image, 0, 0, 0);
   //畫出矩形邊框
   imagerectangle($this->image, 0, 0, $this->width-1, $this->height-1, $border);
  }
  private function  setDisturbColor(){
   for($i=0; $i<$this->disturbColorNum; $i++){
    $color=imagecolorallocate($this->image, rand(0, 255), rand(0, 255), rand(0, 255));
    imagesetpixel($this->image, rand(1, $this->width-2), rand(1, $this->height-2), $color);
   }
   for($i=0; $i<10; $i++){
    $color=imagecolorallocate($this->image, rand(200, 255), rand(200, 255), rand(200, 255));
    imagearc($this->image, rand(-10, $this->width), rand(-10, $this->height), rand(30, 300), rand(20, 200), 55, 44, $color);
   }
  }
  private function createCheckCode(){
//這里主要產(chǎn)生隨機碼，從2開始是為了區(qū)分1和l
   $code="23456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKMNPQRSTUVWXYZ";
   $string='';
   for($i=0; $i < $this->codeNum; $i++){
    $char=$code{rand(0, strlen($code)-1)};
    $string.=$char;
   }
   return $string;
  }
  private function outputText($fontFace=""){
   for($i=0; $i<$this->codeNum; $i++){
    $fontcolor=imagecolorallocate($this->image, rand(0, 128), rand(0, 128), rand(0, 128));
    if($fontFace==""){
     $fontsize=rand(3, 5);
     $x=floor($this->width/$this->codeNum)*$i+3;
     $y=rand(0, $this->height-15);
     imagechar($this->image,$fontsize, $x, $y, $this->checkCode{$i},$fontcolor);
    }else{
     $fontsize=rand(12, 16);
     $x=floor(($this->width-8)/$this->codeNum)*$i+8;
     $y=rand($fontSize+5, $this->height);
     imagettftext($this->image,$fontsize,rand(-30, 30),$x,$y ,$fontcolor, $fontFace, $this->checkCode{$i});
    }
   }
  }
  private function outputImage() {
   if(imagetypes() & IMG_GIF){
    header("Content-Type:image/gif");
    imagepng($this->image);
   }else if(imagetypes() & IMG_JPG){
    header("Content-Type:image/jpeg");
    imagepng($this->image);
   }else if(imagetypes() & IMG_PNG){
    header("Content-Type:image/png");
    imagepng($this->image);
   }else if(imagetypes() & IMG_WBMP){
    header("Content-Type:image/vnd.wap.wbmp");
    imagepng($this->image);
   }else{
    die("PHP不支持圖像創(chuàng)建");
   }
  }
  function __destruct(){
   imagedestroy($this->image);
  }
 }

<?php
session_start();
include "validationcode.class.php";
$code=new ValidationCode(80, 20, 4);
$code->showImage();   //輸出到頁面中供 注冊或登錄使用
$_SESSION["code"]=$code->getCheckCode();  //將驗證碼保存到服務(wù)器中