stream_filter_register
(PHP 5)
stream_filter_register — Register a user defined stream filter
说明
$filtername
, string $classname
)stream_filter_register() allows you to implement your own filter on any registered stream used with all the other filesystem functions (such as fopen() , fread() etc.).
参数
-
filtername -
The filter name to be registered.
-
classname -
To implement a filter, you need to define a class as an extension of php_user_filter with a number of member functions. When performing read/write operations on the stream to which your filter is attached, PHP will pass the data through your filter (and any other filters attached to that stream) so that the data may be modified as desired. You must implement the methods exactly as described in php_user_filter - doing otherwise will lead to undefined behaviour.
返回值
成功时返回 TRUE ， 或者在失败时返回 FALSE 。
stream_filter_register() will return FALSE if the
filtername is already defined.
范例
Example #1 Filter for capitalizing characters on foo-bar.txt stream
The example below implements a filter named strtoupper on the foo-bar.txt stream which will capitalize all letter characters written to/read from that stream.
<?php
class strtoupper_filter extends php_user_filter {
function filter ( $in , $out , & $consumed , $closing )
{
while ( $bucket = stream_bucket_make_writeable ( $in )) {
$bucket -> data = strtoupper ( $bucket -> data );
$consumed += $bucket -> datalen ;
stream_bucket_append ( $out , $bucket );
}
return PSFS_PASS_ON ;
}
}
stream_filter_register ( "strtoupper" , "strtoupper_filter" )
or die( "Failed to register filter" );
$fp = fopen ( "foo-bar.txt" , "w" );
stream_filter_append ( $fp , "strtoupper" );
fwrite ( $fp , "Line1\n" );
fwrite ( $fp , "Word - 2\n" );
fwrite ( $fp , "Easy As 123\n" );
fclose ( $fp );
readfile ( "foo-bar.txt" );
?> 以上例程会输出：
LINE1 WORD - 2 EASY AS 123
Example #2 Registering a generic filter class to match multiple filter names.
<?php
class string_filter extends php_user_filter {
var $mode ;
function filter ( $in , $out , & $consumed , $closing )
{
while ( $bucket = stream_bucket_make_writeable ( $in )) {
if ( $this -> mode == 1 ) {
$bucket -> data = strtoupper ( $bucket -> data );
} elseif ( $this -> mode == 0 ) {
$bucket -> data = strtolower ( $bucket -> data );
}
$consumed += $bucket -> datalen ;
stream_bucket_append ( $out , $bucket );
}
return PSFS_PASS_ON ;
}
function onCreate ()
{
if ( $this -> filtername == 'str.toupper' ) {
$this -> mode = 1 ;
} elseif ( $this -> filtername == 'str.tolower' ) {
$this -> mode = 0 ;
} else {
return false ;
}
return true ;
}
}
stream_filter_register ( "str.*" , "string_filter" )
or die( "Failed to register filter" );
$fp = fopen ( "foo-bar.txt" , "w" );
stream_filter_append ( $fp , "str.toupper" );
fwrite ( $fp , "Line1\n" );
fwrite ( $fp , "Word - 2\n" );
fwrite ( $fp , "Easy As 123\n" );
fclose ( $fp );
readfile ( "foo-bar.txt" );
?> 以上例程会输出：
LINE1 WORD - 2 EASY AS 123
参见
- stream_wrapper_register()
- stream_filter_append() - Attach a filter to a stream
- stream_filter_prepend() - Attach a filter to a stream