从 mySQL 的 base64_decode 生成缩略图

Question

我正在尝试编写从 mySQL 数据库的 base64_decode 生成缩略图的代码，但问题是为什么它说文件不是有效的 JPEG，我确信源文件是纯 JPG 文件格式。那么我无法解决:(

源文件(BASE64_ENCODE): http://pastebin.com/wFBcd79B

view/Helper 文件夹中的 image.php 代码：

<?php
class ImageHelper extends Helper {
    var $helpers = array('Html');
    var $cacheDir = 'imagecache';

    function getfile($i) {

        preg_match_all("/data:(.*);base64,/", $i, $temp_imagetype);

        $imagetype = $temp_imagetype[1][0];

        $image = base64_decode(preg_replace("/data.*base64,/","",$i));

        //echo $image;

        ob_start();

        //header("Content-type: ".$imagetype);
        header('Content-Type: image/jpeg');
        print($image);

        $data = ob_get_clean();

        //file_put_contents($this->webroot.'tmp/temp.jpg', 'test' );

        file_put_contents(ROOT.DS.APP_DIR.DS.WEBROOT_DIR.DS.'tmp/temp.jpg', $data );


        //return ROOT.DS.APP_DIR.DS.WEBROOT_DIR.DS.'tmp/temp2.jpg';
        //return 'temp2.jpg';
        return 'temp.jpg';
    //}
    }


    //source from: http://bakery.cakephp.org/articles/hundleyj/2007/02/16/image-resize-helper and modified for base64_decode
    function resize($path, $width, $height, $aspect = true, $htmlAttributes = array(), $return = false) {
        $types = array(1 => "gif", "jpeg", "png", "swf", "psd", "wbmp"); // used to determine image type 

        //$fullpath = ROOT.DS.APP_DIR.DS.WEBROOT_DIR.DS.$this->themeWeb.IMAGES_URL;

        $fullpath = ROOT.DS.APP_DIR.DS.WEBROOT_DIR.DS.IMAGES_URL;

        $temppath = ROOT.DS.APP_DIR.DS.WEBROOT_DIR.DS.'tmp/';


        //$formImage = imagecreatefromstring(base64_decode(preg_replace("/data.*base64,/","",$path)));

        //$url = $formImage;

        //$path = $this->getfile($path);

        $url = $temppath.$path;

        //$url = preg_replace("/data.*base64,/","",$path);

        //$url = base64_decode($url);

        if (!($size = getimagesize($url)))
            return; // image doesn't exist

        if ($aspect) { // adjust to aspect.
            if (($size[1]/$height) > ($size[0]/$width))  // $size[0]:width, [1]:height, [2]:type
                $width = ceil(($size[0]/$size[1]) * $height);
            else
                $height = ceil($width / ($size[0]/$size[1]));
        }

        $relfile = $this->cacheDir.'/'.$width.'x'.$height.'_'.basename($path); // relative file
        $cachefile = $fullpath.$this->cacheDir.DS.$width.'x'.$height.'_'.basename($path);  // location on server

        if (file_exists($cachefile)) {
        $csize = getimagesize($cachefile);
        $cached = ($csize[0] == $width && $csize[1] == $height); // image is cached
        if (@filemtime($cachefile) < @filemtime($url)) // check if up to date
            $cached = false;
        } else {
            $cached = false;
        }

        if (!$cached) {
            $resize = ($size[0] > $width || $size[1] > $height) || ($size[0] < $width || $size[1] < $height);
        } else {
            $resize = false;
        }

        if ($resize) {
            $image = call_user_func('imagecreatefrom'.$types[$size[2]], $url);
            if (function_exists("imagecreatetruecolor") && ($temp = imagecreatetruecolor ($width, $height))) {
                imagecopyresampled ($temp, $image, 0, 0, 0, 0, $width, $height, $size[0], $size[1]);
            } else {
                $temp = imagecreate ($width, $height);
                imagecopyresized ($temp, $image, 0, 0, 0, 0, $width, $height, $size[0], $size[1]);
            }
                call_user_func("image".$types[$size[2]], $temp, $cachefile);
                imagedestroy ($image);
                imagedestroy ($temp);
        }
        return $this->output(sprintf($this->Html->image($relfile,$htmlAttributes)));
    }
}
?>

'index.php' 中查看文件夹代码：

<?php
    foreach ($products as $product):
        echo $this->Image->resize($this->Image->getfile($product['Product']['image1']), 120, 120, false); 
    endforeach;
    ?>

输出是错误日志：

> Warning (2): imagecreatefromjpeg() [function.imagecreatefromjpeg]:
> gd-jpeg, libjpeg: recoverable error: Premature end of JPEG file 
> [APP/View/Helper/image.php, line 86] 
> Warning (2): imagecreatefromjpeg() [function.imagecreatefromjpeg]:
> '/Users/user/Sites/mycakeapp/app/webroot/tmp/temp.jpg' is not a valid
> JPEG file [APP/View/Helper/image.php, line 86] 
> Warning (2): imagecopyresampled() expects parameter 2 to be resource, boolean given
> [APP/View/Helper/image.php, line 88] 
> Warning (2): imagedestroy() expects parameter 1 to be resource, boolean given
> [APP/View/Helper/image.php, line 94]

Answer 1

您链接到的 Base64 编码数据的长度正好是 216 (65536) 字节。这个数字太圆了，不可能是巧合。

数据库列是否定义为 TEXT？将其转换为更大的内容，例如 MEDIUMTEXT 或 LONGTEXT。

将图像存储在文件系统中会更有意义。虽然数据库可以存储文件等任意数据，但存在一些限制使其不切实际：大量数据必须通过网络从数据库服务器传输到应用程序，因此存在性能问题。巨大的数据库需要更长的时间来备份。并且您可能需要修改数据库设置：

BLOB 或 TEXT 对象的最大大小由其类型决定，但实际可以在客户端和服务器之间传输的最大值由可用内存量和通信缓冲区的大小决定。您可以通过更改 max_allowed_pa​​cket 变量 的值来更改消息缓冲区大小，但您必须对服务器和客户端程序执行此操作。

http://dev.mysql.com/doc/refman/5.0/en /blob.html