(PHP 5, PHP 7, PHP 8)
stream_filter_register — 註冊使用者定義的串流過濾器
filter_name要註冊的過濾器名稱。
class要實作一個篩選器，您需要定義一個繼承自 php_user_filter 的類別，並實作多個成員函式。當您在附加了篩選器的串流上執行讀/寫操作時，PHP 會將資料傳遞 through 您的篩選器（以及附加到該串流的任何其他篩選器），以便根據需要修改資料。您必須完全按照 php_user_filter 中的描述來實作這些方法，否則將導致未定義的行為。
範例 #1 在 foo-bar.txt 串流上將字元轉換為大寫的篩選器
以下範例在 foo-bar.txt 串流上實作了一個名為 strtoupper 的篩選器，它會將寫入/讀取自該串流的所有字母字元轉換為大寫。
<?php
/* 定義我們的過濾器類別 */
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;
}
}
/* 向 PHP 註冊我們的過濾器 */
stream_filter_register("strtoupper", "strtoupper_filter")
or die("無法註冊過濾器");
$fp = fopen("foo-bar.txt", "w");
/* 將已註冊的過濾器附加到剛開啟的串流 */
stream_filter_append($fp, "strtoupper");
fwrite($fp, "Line1\n");
fwrite($fp, "Word - 2\n");
fwrite($fp, "Easy As 123\n");
fclose($fp);
/* 讀回內容
*/
readfile("foo-bar.txt");
?>以上範例將輸出
LINE1 WORD - 2 EASY AS 123
範例 #2 註冊一個通用的過濾器類別以匹配多個過濾器名稱。
<?php
/* Define our filter class */
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 {
/* Some other str.* filter was asked for,
report failure so that PHP will keep looking */
return false;
}
return true;
}
}
/* Register our filter with PHP */
stream_filter_register("str.*", "string_filter")
or die("Failed to register filter");
$fp = fopen("foo-bar.txt", "w");
/* Attach the registered filter to the stream just opened
We could alternately bind to str.tolower here */
stream_filter_append($fp, "str.toupper");
fwrite($fp, "Line1\n");
fwrite($fp, "Word - 2\n");
fwrite($fp, "Easy As 123\n");
fclose($fp);
/* Read the contents back out
*/
readfile("foo-bar.txt");
?>以上範例將輸出
LINE1 WORD - 2 EASY AS 123