validationCode.php

<?php
	class ValidationCode{
		private $width;
		private $height;
		private $codeNum;
		private $checkCode;
		private $image;
		//构造函数
		function __construct($width=60, $height=20, $codeNum=4)
		{
			$this->width = $width;
			$this->height = $height;
			$this->codeNum = $codeNum;
			$this->checkCode = $this->createCheckCode();
		}
		//显示图片函数
		function showImage()
		{
			$this->getCreateImage();
			$this->outputText();
			$this->setDisturbColor();
			$this->outputImage();
		}

		//获取验证码
		function getCheckCode()
		{
			return $this->checkCode;
		}

		//创建图像
		private function getCreateImage()
		{
			$this->image = imagecreate($this->width, $this->height);
			$back = imagecolorallocate($this->image, 255, 255, 255);
			$border = imagecolorallocate($this->image, 0, 0, 0);
			imagerectangle($this->image, 0, 0, $this->width-1, $this->height-1, $border);
		}

		//获取验证码
		private function createCheckCode()
		{
			for($i=0 ; $i<$this->codeNum ; $i++)
			{
				$number = rand(0,1);
				switch ($number) {
					case 0:
						$rand_number = rand(48, 57);
						break;
					case 1:
					    $rand_number = rand(97, 122);
					    break;
				}
				$ascii = sprintf("%c",$rand_number);
				$ascii_number .= $ascii;
			}
		    return $ascii_number;
		}

		//添加干扰信息
		private function setDisturbColor()
		{
			for($i=0 ; $i<=100 ; $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);
			}
		}

		//添加验证码到图像
		private function outputText()
		{
			for($i=0 ; $i<=$this->codeNum ; $i++)
			{
				$bg_color = imagecolorallocate($this->image, rand(0,200), rand(0,200), rand(0,200));
				$x = floor($this->width/$this->codeNum)*$i + 3;
				$y = rand(0, $this->height-15);
				imagechar($this->image, 5, $x, $y, $this->checkCode[$i], $bg_color);
			}
		}

		//根据对各种格式的图片的支持输出图像
		private function outputImage()
		{
			ob_clean();
			if(imagetypes() & IMG_GIF)
			{
				header("Content-type:image/gif");
				imagegif($this->image);
			}elseif(imagetypes() & IMG_JPG)
			{
				header("Content-type:image/jpeg");
				imagegif($this->image, "", 0.5);
			}elseif(imagetypes() & IMG_PNG)
			{
				header("Content-type:image/png");
				imagegif($this->image);
			}elseif(imagetypes() & IMG_WBMP)
			{
				header("Content-type:image/vnd.wap.wbmp");
				imagegif($this->image);
			}
			else
			{
               die("PHP不支持图像创建");
			}
		}
		function __destruct(){
			imagedestroy($this->image);
		}
	}
?>