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stream_filter_register

stream_filter_register

(PHP 5)

stream_filter_registerRegister a user defined stream filter

说明

bool stream_filter_register ( string $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 as defined below. 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 below - doing otherwise will lead to undefined behaviour.

int filter ( resource $in , resource $out , int &$consumed , bool $closing )

This method is called whenever data is read from or written to the attached stream (such as with fread() or fwrite()). in is a resource pointing to a bucket brigade which contains one or more bucket objects containing data to be filtered. out is a resource pointing to a second bucket brigade into which your modified buckets should be placed. consumed, which must always be declared by reference, should be incremented by the length of the data which your filter reads in and alters. In most cases this means you will increment consumed by $bucket->datalen for each $bucket. If the stream is in the process of closing (and therefore this is the last pass through the filterchain), the closing parameter will be set to TRUE. The filter() method must return one of three values upon completion.

Return Value Meaning
PSFS_PASS_ON Filter processed successfully with data available in the out bucket brigade.
PSFS_FEED_ME Filter processed successfully, however no data was available to return. More data is required from the stream or prior filter.
PSFS_ERR_FATAL (default) The filter experienced an unrecoverable error and cannot continue.
bool onCreate ( void ) This method is called during instantiation of the filter class object. If your filter allocates or initializes any other resources (such as a buffer), this is the place to do it. Your implementation of this method should return FALSE on failure, or TRUE on success. When your filter is first instantiated, and yourfilter->onCreate() is called, a number of properties will be available as shown in the table below.

Property Contents
FilterClass->filtername A string containing the name the filter was instantiated with. Filters may be registered under multiple names or under wildcards. Use this property to determine which name was used.
FilterClass->params The contents of the params parameter passed to stream_filter_append() or stream_filter_prepend().
FilterClass->stream The stream resource being filtered. Maybe available only during filter() calls when the closing parameter is set to FALSE.
void onClose ( void )

This method is called upon filter shutdown (typically, this is also during stream shutdown), and is executed after the flush method is called. If any resources were allocated or initialized during onCreate() this would be the time to destroy or dispose of them.

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($fp"Line1 ");
fwrite($fp"Word - 2 ");
fwrite($fp"Easy As 123 ");

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($fp"Line1 ");
fwrite($fp"Word - 2 ");
fwrite($fp"Easy As 123 ");

fclose($fp);


readfile("foo-bar.txt");
?>

以上例程会输出:

LINE1
WORD - 2
EASY AS 123

参见


  • set_socket_blocking
  • stream_bucket_append
  • stream_bucket_make_writeable
  • stream_bucket_new
  • stream_bucket_prepend
  • stream_context_create
  • stream_context_get_default
  • stream_context_get_options
  • stream_context_get_params
  • stream_context_set_default
  • stream_context_set_option
  • stream_context_set_params
  • stream_copy_to_stream
  • stream_encoding
  • stream_filter_append
  • stream_filter_prepend
  • stream_filter_register
  • stream_filter_remove
  • stream_get_contents
  • stream_get_filters
  • stream_get_line
  • stream_get_meta_data
  • stream_get_transports
  • stream_get_wrappers
  • stream_is_local
  • stream_notification_callback
  • stream_register_wrapper
  • stream_resolve_include_path
  • stream_select
  • stream_set_blocking
  • stream_set_read_buffer
  • stream_set_timeout
  • stream_set_write_buffer
  • stream_socket_accept
  • stream_socket_client
  • stream_socket_enable_crypto
  • stream_socket_get_name
  • stream_socket_pair
  • stream_socket_recvfrom
  • stream_socket_sendto
  • stream_socket_server
  • stream_socket_shutdown
  • stream_supports_lock
  • stream_wrapper_restore
  • stream_wrapper_unregister
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