stream_filter_append
(PHP 4 >= 4.3.0, PHP 5, PHP 7)
stream_filter_append — Attach a filter to a stream
说明
$stream ,
string $filtername [,
int $read_write [,
mixed $params ]] ) :
resource
Adds filtername to the list of filters attached to stream.
参数
-
stream -
The target stream.
-
filtername -
The filter name.
-
read_write -
By default, stream_filter_append() will attach the filter to the read filter chain if the file was opened for reading (i.e. File Mode: r, and/or +). The filter will also be attached to the write filter chain if the file was opened for writing (i.e. File Mode: w, a, and/or +).
STREAM_FILTER_READ,STREAM_FILTER_WRITE, and/orSTREAM_FILTER_ALLcan also be passed to theread_writeparameter to override this behavior. -
params -
This filter will be added with the specified
paramsto the end of the list and will therefore be called last during stream operations. To add a filter to the beginning of the list, use stream_filter_prepend().
返回值
Returns a resource on success or FALSE on failure. The resource can be used to refer to this filter instance during a call to stream_filter_remove().
FALSE is returned if stream is not a resource or if filtername cannot be located.
更新日志
| 版本 | 说明 |
|---|---|
| 5.1.0 | Prior to PHP 5.1.0, this function returns TRUE on success 或者在失败时返回 FALSE. |
范例
Example #1 Controlling where filters are applied
<?php
/* Open a test file for reading and writing */
$fp = fopen('test.txt', 'w+');
/* Apply the ROT13 filter to the
* write filter chain, but not the
* read filter chain */
stream_filter_append($fp, "string.rot13", STREAM_FILTER_WRITE);
/* Write a simple string to the file
* it will be ROT13 transformed on the
* way out */
fwrite($fp, "This is a test\n");
/* Back up to the beginning of the file */
rewind($fp);
/* Read the contents of the file back out.
* Had the filter been applied to the
* read filter chain as well, we would see
* the text ROT13ed back to its original state */
fpassthru($fp);
fclose($fp);
/* Expected Output
---------------
Guvf vf n grfg
*/
?>
注释
Note: When using custom (user) filters
stream_filter_register() must be called first in order to register the desired user filter tofiltername.
Note: Stream data is read from resources (both local and remote) in chunks, with any unconsumed data kept in internal buffers. When a new filter is appended to a stream, data in the internal buffers is processed through the new filter at that time. This differs from the behavior of stream_filter_prepend().
Note: When a filter is added for read and write, two instances of the filter are created. stream_filter_append() must be called twice with
STREAM_FILTER_READandSTREAM_FILTER_WRITEto get both filter resources.
参见
- stream_filter_register() - Register a user defined stream filter
- stream_filter_prepend() - Attach a filter to a stream
- stream_get_filters() - 获取已注册的数据流过滤器列表
