效果如图：
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文件都放到了同一文件夹下。
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CreateImage.class.php
<?phpclass ValidationCode{ private $width,$height,$codenum; public $checkcode; //产生的验证码 private $checkimage; //验证码图片 private $disturbColor = ''; //干扰像素 function __construct($width='80',$height='20',$codenum='4') { $this->width=$width; $this->height=$height; $this->codenum=$codenum; } function outImg() { //输出头 $this->outFileHeader(); //产生验证码 $this->createCode(); //产生图片 $this->createImage(); //设置干扰像素 $this->setDisturbColor(); //往图片上写验证码 $this->writeCheckCodeToImage(); imagepng($this->checkimage); imagedestroy($this->checkimage); } private function outFileHeader() { header ('Content-type: image/png'); } private function createCode() { $this->checkcode = strtoupper(substr(md5(rand()),0,$this->codenum)); } private function createImage() { $this->checkimage = @imagecreate($this->width,$this->height); $back = imagecolorallocate($this->checkimage,255,255,255); $border = imagecolorallocate($this->checkimage,0,0,0); imagefilledrectangle($this->checkimage,0,0,$this->width - 1,$this->height - 1,$back); // 白色底 imagerectangle($this->checkimage,0,0,$this->width - 1,$this->height - 1,$border); // 黑色边框 } private function setDisturbColor() { for ($i=0;$i<=200;$i++) { $this->disturbColor = imagecolorallocate($this->checkimage, rand(0,255), rand(0,255), rand(0,255)); imagesetpixel($this->checkimage,rand(2,128),rand(2,38),$this->disturbColor); } } private function writeCheckCodeToImage() { for ($i=0;$i<=$this->codenum;$i++) { $bg_color = imagecolorallocate ($this->checkimage, rand(0,255), rand(0,128), rand(0,255)); $x = floor($this->width/$this->codenum)*$i; $y = rand(0,$this->height-15); imagechar ($this->checkimage, rand(5,8), $x, $y, $this->checkcode[$i], $bg_color); } } function __destruct() { unset($this->width,$this->height,$this->codenum); }}?
checks.php
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<?phpini_set('display_errors','off');session_start();header("content-type:image/png"); //设置创建图像的格式$image_width=70; //设置图像宽度$image_height=18; //设置图像高度srand(microtime()*100000); //设置随机数的种子for($i=0;$i<4;$i++){ //循环输出一个4位的随机数 $new_number.=dechex(rand(0,15));}$_SESSION[check_checks]=$new_number; //将获取的随机数验证码写入到SESSION变量中 $num_image=imagecreate($image_width,$image_height); //创建一个画布imagecolorallocate($num_image,255,255,255); //设置画布的颜色for($i=0;$i<strlen($_SESSION[check_checks]);$i++){ //循环读取SESSION变量中的验证码 $font=mt_rand(3,5); //设置随机的字体 $x=mt_rand(1,8)+$image_width*$i/4; //设置随机字符所在位置的X坐标 $y=mt_rand(1,$image_height/4); //设置随机字符所在位置的Y坐标 $color=imagecolorallocate($num_image,mt_rand(0,100),mt_rand(0,150),mt_rand(0,200)); //设置字符的颜色 imagestring($num_image,$font,$x,$y,$_SESSION[check_checks][$i],$color); //水平输出字符}imagepng($num_image); //生成PNG格式的图像imagedestroy($num_image); //释放图像资源?>?
index.php
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<?phpheader("content-type:text/html; charset=utf-8");session_start();if(!empty($_POST["Submit"])){$checks=$_POST["checks"];if($checks==""){echo "<script> alert('验证码不能为空');window.location.href='index.php';</script>";}if($checks==$_SESSION[check_checks]){ echo "<script> alert('用户登录成功!');window.location.href='index.php';</script>";}else{ echo "<script> alert('您输入的验证码不正确!');window.location.href='index.php';</script>";}}?><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>rand函数的应用</title><style type="text/css"><!--.STYLE1 { font-size: 12px; color: #FFFFFF; font-weight: bold;}.style2 {font-weight: bold; font-size: 12px;}--></style></head><body><form name="form" method="post" action=""><input type="hidden" name="Submit" id="Submit" value="1" /> <table width="1003" border="0" cellspacing="0" cellpadding="0"> <tr> <td width="168" height="169" background="images/index_01.gif"> </td> <td width="685" background="images/index_02.gif"> </td> <td width="150" background="images/index_03.gif"> </td> </tr> <tr> <td width="168" height="311" background="images/index_04.gif"> </td> <td background="images/index_05.gif"><table width="675" height="169" border="0" cellpadding="0" cellspacing="0"> <tr> <td height="43" align="center" valign="baseline"> </td> <td align="center" valign="middle"> </td> <td align="center" valign="baseline"> </td> </tr> <tr> <td width="382" height="24" align="center" valign="baseline"> </td> <td width="207" height="24" valign="middle"><span class="style2">用户名</span><span class="STYLE1"> <input name="txt_user" id="txt_user" style="height:20px " size="10"> </span></td> <td width="86" height="24" align="center" valign="baseline"> </td> </tr> <tr> <td height="24" align="center" valign="baseline"> </td> <td height="24" valign="middle"><span class="style2">密?码</span><span class="STYLE1"> <input name="txt_pwd" type="password" id="txt_pwd" style="FONT-SIZE: 9pt; height:20px" size="10"> </span></td> <td height="24" align="center" valign="baseline"> </td> </tr> <tr> <td height="24" align="center" valign="baseline"> </td> <td height="24" valign="middle"><span class="style2">验证码</span><span class="STYLE1"> <input name="checks" size="6" style="height:20px "> <img src="./checks.php" width="70" height="18" border="0" align="bottom"></span> </td> <td height="24" align="center" valign="baseline"> </td> </tr> <tr> <td height="40" align="center" valign="baseline"> </td> <td align="center" valign="baseline"> <input type="submit" id="Submit" name="Submit" value="登录" /></td> <td align="center" valign="baseline"> </td> </tr> </table></td> <td background="images/index_06.gif"> </td> </tr> <tr> <td height="100"> </td> <td> </td> <td> </td> </tr> </table></form></body></html>?
************************************容易出现的问题*************
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1.未开启php_gd2.dll? 去php.ini将其前面的“ ;”去掉
2.上面的checks.php中<?前面有空格或者内容
3.字符编码改为统一的
4.最容易忽略的一点：
? 你本机上的环境是将报错提示全部打开的,所以在输出时有系统的未定义提示信息也跟着一起输出了,这样生成的图片肯定就不正常了,方法有两,在ValidationCode.php和checks.php文件开头加上ini_set('display_errors',?'Off');??就ok了
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