PHP，使用 Header() 显示图像

PHP, display image with Header()(PHP，使用 Header() 显示图像)

问题描述

我正在显示来自我的网络根目录之外的图像，如下所示:

I'm displaying images from outside my web root, like this:

header('Content-type:image/png');
readfile($fullpath);

content-type: image/png 让我很困惑.

The content-type: image/png is what confuses me.

其他人帮我编写了这段代码，但我注意到并非所有图像都是 PNG.许多是 jpg 或 gif.
而且它们仍然显示成功.

Someone else helped me out with this code, but I noticed that not all images are PNG. Many are jpg or gif.
And still they are displayed successfully.

有人知道为什么吗?

推荐答案

最好的解决方案是读入文件，然后决定它是哪种图像并发出适当的标题

The best solution would be to read in the file, then decide which kind of image it is and send out the appropriate header

$filename = basename($file);
$file_extension = strtolower(substr(strrchr($filename,"."),1));

switch( $file_extension ) {
    case "gif": $ctype="image/gif"; break;
    case "png": $ctype="image/png"; break;
    case "jpeg":
    case "jpg": $ctype="image/jpeg"; break;
    case "svg": $ctype="image/svg+xml"; break;
    default:
}

header('Content-type: ' . $ctype);

(注意:JPG 文件的正确内容类型是 image/jpeg)