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このドキュメントでは、 php中国語ネットマニュアル リリース
(PHP 4, PHP 5, PHP 7)
dl — 运行时载入一个 PHP 扩展
$library
)
载入指定参数 library
的 PHP 扩展。
使用 extension_loaded() 来测试指定的扩展是否已经激活。 这既能用于内建的扩展也可以用于动态加载的扩展(既可以通过 php.ini 也可以通过 dl() )。
在 PHP 5.3 里,此函数被某些 SAPI 移除了。
library
此参数仅仅是要加载的扩展的文件名,依赖于你的平台。 比如,sockets(作为共享模块编译,而不是默认的!)在 Unix 平台上称为 sockets.so 而 在 Windows 平台上是 php_sockets.dll。
扩展加载的目录依赖于你的平台:
Windows - 如果没有在 php.ini 里明确设置,扩展默认会从 C:\php4\extensions\ (PHP 4) 或 C:\php5\ (PHP 5)加载。
Unix - 如果没有在 php.ini 里明确设置,默认的扩展目录依赖于
成功时返回 TRUE
, 或者在失败时返回 FALSE
。 如果加载模块的功能是无效或者禁用的(既可以通过设置关闭 enable_dl 设置,也可以通过启用 php.ini 里的 安全模式)将导致一个 E_ERROR
并中断执行。
如果因为指定的库无法加载而导致 dl() 失败,除了返回 FALSE
,还会产生一个 E_WARNING
的消息。
Example #1 dl() 例子
<?php
// 加载一个扩展的例子,基于操作系统
if (! extension_loaded ( 'sqlite' )) {
if ( strtoupper ( substr ( PHP_OS , 0 , 3 )) === 'WIN' ) {
dl ( 'php_sqlite.dll' );
} else {
dl ( 'sqlite.so' );
}
}
// 或者,PHP_SHLIB_SUFFIX 常量在 PHP 4.3.0 后有效
if (! extension_loaded ( 'sqlite' )) {
$prefix = ( PHP_SHLIB_SUFFIX === 'dll' ) ? 'php_' : '' ;
dl ( $prefix . 'sqlite.' . PHP_SHLIB_SUFFIX );
}
?>
版本 | 说明 |
---|---|
5.3.0 | 由于稳定性, dl() 在某些 SAPI 中被禁用。仅仅允许 dl() 的 SAPI 为 CLI 和 Embed。 使用 扩展加载指令 作为替代。 |
Note:
当 PHP 以支持 ZTS 构建时,不支持 dl() 。 使用 扩展加载指令 作为替代。
Note:
在某些 Unix 平台上, dl() 是大小写敏感的。
Note: 当 PHP 运行在 安全模式 时,不能使用此函数。
[#1] K. C. [2014-11-18 15:42:14]
It would be nice to know which SAPIs removed the function.
Telling me 'This function has been removed from some SAPIs in PHP 5.3.' is pretty much useless and I feel mocked. Or do the writers of the documentation don't know from which SAPIs it has been removed?
[#2] fabrizim at owlwatch dot com [2013-05-03 20:24:01]
As noted in the documentation:
Changelog 5.3: dl() is now disabled in some SAPIs due to stability issues. The only SAPIs that allow dl() are CLI and Embed. Use the Extension Loading Directives instead.
If using PEAR libraries that try to load extensions, like Image_Transform which will try to load ImageMagik, and the "enable_dl" directive is set to 1 in your php.ini, you may end up with a hard to find error (white screen of death).
One "solution" is to change the enable_dl directive to 0 in the php.ini. It may have adverse affects if you are using php on command line that requires the "dl" function, but I think in most cases its okay.
[#3] Anonymous [2010-12-04 10:36:19]
this function errors out as the dl() cannot take the absolute path..."Warning: dl() [function.dl]: Temporary module name should contain only filename in /home/..."
[#4] shaunspiller at spammenot-gmail dot com [2009-01-29 00:34:18]
dl is awkward because the filename format is OS-dependent and because it can complain if the extension is already loaded. This wrapper function fixes that:
<?php
function load_lib($n, $f = null) {
return extension_loaded($n) or dl(((PHP_SHLIB_SUFFIX === 'dll') ? 'php_' : '') . ($f ? $f : $n) . '.' . PHP_SHLIB_SUFFIX);
}
?>
Examples:
<?php
// ensure we have SSL and MySQL support
load_lib('openssl');
load_lib('mysql');
// a rare few extensions have a different filename to their extension name, such as the image (gd) library, so we specify them like this:
load_lib('gd', 'gd2');
?>
[#5] mag_2000 at front dot ru [2005-12-06 11:13:44]
<?php
function dl_local( $extensionFile ) {
//make sure that we are ABLE to load libraries
if( !(bool)ini_get( "enable_dl" ) || (bool)ini_get( "safe_mode" ) ) {
die( "dh_local(): Loading extensions is not permitted.\n" );
}
//check to make sure the file exists
if( !file_exists( $extensionFile ) ) {
die( "dl_local(): File '$extensionFile' does not exist.\n" );
}
//check the file permissions
if( !is_executable( $extensionFile ) ) {
die( "dl_local(): File '$extensionFile' is not executable.\n" );
}
//we figure out the path
$currentDir = getcwd() . "/";
$currentExtPath = ini_get( "extension_dir" );
$subDirs = preg_match_all( "/\//" , $currentExtPath , $matches );
unset( $matches );
//lets make sure we extracted a valid extension path
if( !(bool)$subDirs ) {
die( "dl_local(): Could not determine a valid extension path [extension_dir].\n" );
}
$extPathLastChar = strlen( $currentExtPath ) - 1;
if( $extPathLastChar == strrpos( $currentExtPath , "/" ) ) {
$subDirs--;
}
$backDirStr = "";
for( $i = 1; $i <= $subDirs; $i++ ) {
$backDirStr .= "..";
if( $i != $subDirs ) {
$backDirStr .= "/";
}
}
//construct the final path to load
$finalExtPath = $backDirStr . $currentDir . $extensionFile;
//now we execute dl() to actually load the module
if( !dl( $finalExtPath ) ) {
die();
}
//if the module was loaded correctly, we must bow grab the module name
$loadedExtensions = get_loaded_extensions();
$thisExtName = $loadedExtensions[ sizeof( $loadedExtensions ) - 1 ];
//lastly, we return the extension name
return $thisExtName;
}//end dl_local()
?>
[#6] endofyourself at yahoo dot com [2003-10-18 04:12:50]
If you need to load an extension from the CURRENT local directory because you do not have privelages to place the extension in your servers PHP extensions directory, this function i wrote may be of use to you
<?php
function dl_local( $extensionFile ) {
//make sure that we are ABLE to load libraries
if( !(bool)ini_get( "enable_dl" ) || (bool)ini_get( "safe_mode" ) ) {
die( "dh_local(): Loading extensions is not permitted.\n" );
}
//check to make sure the file exists
if( !file_exists( $extensionFile ) ) {
die( "dl_local(): File '$extensionFile' does not exist.\n" );
}
//check the file permissions
if( !is_executable( $extensionFile ) ) {
die( "dl_local(): File '$extensionFile' is not executable.\n" );
}
//we figure out the path
$currentDir = getcwd() . "/";
$currentExtPath = ini_get( "extension_dir" );
$subDirs = preg_match_all( "/\//" , $currentExtPath , $matches );
unset( $matches );
//lets make sure we extracted a valid extension path
if( !(bool)$subDirs ) {
die( "dl_local(): Could not determine a valid extension path [extension_dir].\n" );
}
$extPathLastChar = strlen( $currentExtPath ) - 1;
if( $extPathLastChar == strrpos( $currentExtPath , "/" ) ) {
$subDirs--;
}
$backDirStr = "";
for( $i = 1; $i <= $subDirs; $i++ ) {
$backDirStr .= "..";
if( $i != $subDirs ) {
$backDirStr .= "/";
}
}
//construct the final path to load
$finalExtPath = $backDirStr . $currentDir . $extensionFile;
//now we execute dl() to actually load the module
if( !dl( $finalExtPath ) ) {
die();
}
//if the module was loaded correctly, we must bow grab the module name
$loadedExtensions = get_loaded_extensions();
$thisExtName = $loadedExtensions[ sizeof( $loadedExtensions ) - 1 ];
//lastly, we return the extension name
return $thisExtName;
}//end dl_local()
?>