用html或php怎样简单的实现单击下载图片

下面是来自ci的下载辅助函数，基本原理是生成一个能下载数据的http header，然后把文件数据发送过去就行啦。应该是可以直接用的，如果还有什么问题，我再看看啊

$data = file_get_contents("/path/to/photo.jpg")// 读文件内容

$name = 'myphoto.jpg'

force_download($name, $data)

function force_download($filename = '', $data = '')

{

if ($filename == '' OR $data == '')

{

return FALSE

}

// Try to determine if the filename includes a file extension.

// We need it in order to set the MIME type

if (FALSE === strpos($filename, '.'))

{

return FALSE

}

// Grab the file extension

$x = explode('.', $filename)

$extension = end($x)

$mimes = array( 'bmp' =>array('image/bmp','application/octet-stream'),

'gif' =>array('image/gif','application/octet-stream'),

'jpeg' => array('image/jpeg', 'image/pjpeg', 'application/octet-stream'),

'jpg' => array('image/jpeg', 'image/pjpeg', 'application/octet-stream'),

'jpe' => array('image/jpeg', 'image/pjpeg', 'application/octet-stream'),

'png' => array('image/png', 'image/x-png', 'application/octet-stream')

)

// Set a default mime if we can't find it

if ( ! isset($mimes[$extension]))

{

$mime = 'application/octet-stream'

}

else

{

$mime = (is_array($mimes[$extension])) ? $mimes[$extension][0] : $mimes[$extension]

}

// Generate the server headers

if (strstr($_SERVER['HTTP_USER_AGENT'], "MSIE"))

{

header('Content-Type: "'.$mime.'"')

header('Content-Disposition: attachmentfilename="'.$filename.'"')

header('Expires: 0')

header('Cache-Control: must-revalidate, post-check=0, pre-check=0')

header("Content-Transfer-Encoding: binary")

header('Pragma: public')

header("Content-Length: ".strlen($data))

}

else

{

header('Content-Type: "'.$mime.'"')

header('Content-Disposition: attachmentfilename="'.$filename.'"')

header("Content-Transfer-Encoding: binary")

header('Expires: 0')

header('Pragma: no-cache')

header("Content-Length: ".strlen($data))

}

exit($data)

}

html的图片的各种路径代码

物理路径：假如你的图片在D盘的images文件下，文件名称为 tupian.jpeg的话用下面的格式。<img src="file:///D|/images/tupian.jpeg"/>

相对路径：如果是网站的话，则为下面的：<img src="images/tupian.jpeg"/>

这个为html文件和images同一目录的写法：<img src="tupian.jpeg"/>

这个为图片和html文件同一目录的写法:<img src="../images/tupian.jpeg"/>

这种为html所在文件夹和images文件夹处同一目录也是网站的主目录下的写法

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