PHP验证码图片显示不了，显示的是一个红色的叉叉。代码如下：
image.php
<?php session_start(); if(isset($_POST['submit'])){ if(trim($_POST["test"])==$_SESSION['validationcode']){ echo '提交成功<br>'; }else{ echo '<font color="red">验证码输入错误！！</font><br>'; } }?><html> <head> <title>Image</title> <meta http-equiv="content-type" content="text/html;charset=gb2312"> <script> function newgdcode(obj,url) { //后面传递一个随机参数，否则在IE7和火狐下，不刷新图片 obj.src = url+ '?nowtime=' + new Date().getTime(); } </script> </head> <body> <img src="/static/imghwm/default1.png" data-src="imgcode.php" class="lazy" alt="看不清楚，换一张" style="max-width:90%" onClick="javascript: newgdcode(this,this.src);" /> <form method="POST" action="image.php"> <input type="text" name="test"><br> <input type="submit" name="submit" value="提交"> </form> </body></html> imgcode.php
<?php session_start(); require_once('ValidationCode.php'); $image = new ValidationCode(60,20,4); $image->showImage(); $_SESSION['validationcode'] =$image->getCheckCode(); ?> ValidationCode.php
<?php /* 类ValidationCode声明在文件名为Validationcode.php中 */ /* 通过该类的对象可以动态获取验证码图片，和验证码字符串 */ class ValidationCode { private $width; //验证码图片的宽度 private $height; //验证码图片的高度 private $codeNum; //验证码字符的个数 private $checkCode; //验证码字符 private $image; //验证码画布 /* 构造方法用来实例化验证码对象，并为一些成员属性初使化 */ /* 参数width: 设置验证码图片的宽度，默认宽度值为60像素 */ /* 参数height: 设置验证码图片的高度，默认高度值为20像素 */ /* 参数codeNum: 设置验证码中字母和数字的个数，默认个数为4个 */ function __construct($width=60, $height=20, $codeNum=4) { $this->width=$width; //为成员属性width初使化 $this->height=$height; //为成员属性height初使化 $this->codeNum=$codeNum; //为成员属性codeNum初使化 $this->checkCode=$this->createCheckCode(); //为成员属性checkCode初使化 } function showImage(){ //通过访问该方法向浏览器中输出图像 $this->getCreateImage(); //调用内部方法创建画布并对其进行初使化 $this->outputText(); //向图像中输出随机的字符串 $this->setDisturbColor(); //向图像中设置一些干扰像素 $this->outputImage(); //生成相应格式的图像并输出 } function getCheckCode(){ //访问该方法获取随机创建的验证码字符串 return $this->checkCode; //返回成员属性$checkCode保存的字符串 } private function getCreateImage(){ //用来创建图像资源，并初使化背影 $this->image=imageCreate($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); } private function createCheckCode(){ //随机生成用户指定个数的字符串 for($i=0;$i<$this->codeNum;$i++) { $number=rand(0,2); switch($number){ case 0 : $rand_number=rand(48,57);break; //数字 case 1 : $rand_number=rand(65,90);break; //大写字母 case 2 : $rand_number=rand(97,122);break; //小写字母 } $ascii=sprintf("%c",$rand_number); $ascii_number=$ascii_number.$ascii; } return $ascii_number; } private function setDisturbColor() { //设置干扰像素，向图像中输出不同颜色的100个点 for ($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); } } private function outputText() { //随机颜色、随机摆放、随机字符串向图像中输出 for ($i=0;$i<=$this->codeNum;$i++) { $bg_color = imagecolorallocate($this->image, rand(0,255), rand(0,128), rand(0,255)); $x = floor($this->width/$this->codeNum)*$i+3; $y = rand(0,$this->height-15); imagechar($this->image, 5, $x, $y, $this->checkCode[$i], $bg_color); } } private function outputImage(){ //自动检测GD支持的图像类型，并输出图像 if(imagetypes() & IMG_GIF){ //判断生成GIF格式图像的函数是否存在 header("Content-type: image/gif"); //发送标头信息设置MIME类型为image/gif imagegif($this->image); //以GIF格式将图像输出到浏览器 }elseif(imagetypes() & IMG_JPG){ //判断生成JPG格式图像的函数是否存在 header("Content-type: image/jpeg"); //发送标头信息设置MIME类型为image/jpeg imagejpeg($this->image, "", 0.5); //以JPEN格式将图像输出到浏览器 }elseif(imagetypes() & IMG_PNG){ //判断生成PNG格式图像的函数是否存在 header("Content-type: image/png"); //发送标头信息设置MIME类型为image/png imagepng($this->image); //以PNG格式将图像输出到浏览器 }elseif(imagetypes() & IMG_WBMP){ //判断生成WBMP格式图像的函数是否存在 header("Content-type: image/vnd.wap.wbmp"); //发送标头为image/wbmp imagewbmp($this->image); //以WBMP格式将图像输出到浏览器 }else{ //如果没有支持的图像类型 die("PHP不支持图像创建！"); //不输出图像，输出一错误消息，并退出程序 } } function __destruct(){ //当对象结束之前销毁图像资源释放内存 imagedestroy($this->image); //调用GD库中的方法销毁图像资源 } }?>
回复讨论(解决方案)
哭，没有大虾帮小弟一下吗？
是因为class ValidationCode这个类的析构函数出了问题，
请把function __destruct()这个函数作这样的改写，就可以正常显示了。
function __destruct(){ //当对象结束之前销毁图像资源释放内存 if($this->image) imagedestroy($this->image); //调用GD库中的方法销毁图像资源 } 我这边写了个测试用例，请确保在运行之前你的服务器上安装了GD库，否则是无法正常显示的。
$a = new ValidationCode();$a->showImage();
还是不行，你说的测试代码放哪里？
经测试，你的代码没有问题，所有表现都正常
如果你的程序文件是保存成 utf-8 编码的，请检查是否有 BOM 头
已经改了，还是不行，还有，我把代码发给别人，别人可以看到验证码，为什么我的机子看不到。
<?phprequire_once('ValidationCode.php');$image = new ValidationCode(60,20,4); $image->showImage(); 执行上述代码，看有什么结果
结果是只显示一个红色叉叉，就是HTML找不到图片那种样子。
很简单的问题,肯定是你本机上的环境是将报错提示全部打开的,因为你的代码有使用未定义变量的情况,如$ascii_number=$ascii_number.$ascii;这里,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开头加上ini_set('display_errors', 'Off'); 或者就根据提示将那些未定义的变量全一个个初始化一下就OK了,
楼主我以前也用到过验证码使用不了的情况！
看了下，您的验证码貌似用session，如果是虚拟主机的话，请确认下，主机是否支持seesion！
完了，分数给错了，应该给9楼的。。。。
哎，看来我是捡了便宜，改天我把分再还给九楼好了！
太感谢九楼了，我也遇到同样的问题，现在解决了。。。。。
我也是啊,解决了
还得谢谢楼主，让学了不少知识阿
9楼乃神人也！
我的问题也解决了！！
经测试，你的代码没有问题，所有表现都正常
如果你的程序文件是保存成 utf-8 编码的，请检查是否有 BOM 头
多谢，我忙了一个小时在你这找到答案～
请问楼主你是怎样修改这个代码，究竟是什么出错了~~~
9楼解决问题了。
有人在吗？我按上面的代码执行，为什吗还是出现不了图片？
检查php.ini配置文件，是否开启了GD2,extension=php_gd2.dll，前面的；号去掉。
经测试，你的代码没有问题，所有表现都正常
如果你的程序文件是保存成 utf-8 编码的，请检查是否有 BOM 头
哎，用记事本编写代码的同志们，伤不起啊
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