class RecursiveFileFilterIterator extends FilterIterator
{
 // 满足条件的扩展名
 protected $ext = array('jpg','gif');
 /**
  * 提供 $path 并生成对应的目录迭代器
  */
 public function __construct($path)
 {
   parent::__construct(new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path)));
 }
 /**
  * 检查文件扩展名是否满足条件
  */
 public function accept()
 {
   $item = $this->getInnerIterator();
   if ($item->isFile() && in_array(pathinfo($item->getFilename(), PATHINFO_EXTENSION), $this->ext))
   {
     return TRUE;
   }
 }
}
// 实例化
foreach (new RecursiveFileFilterIterator('D:/history') as $item)
{
 echo $item . PHP_EOL;
}

public class DirectoryContents
{
 public static void main(String[] args) throws IOException
 {
   File f = new File("."); // current directory
   FilenameFilter textFilter = new FilenameFilter()
   {
     public boolean accept(File dir, String name)
     {
       String lowercaseName = name.toLowerCase();
       if (lowercaseName.endsWith(".txt"))
       {
         return true;
       }
       else
       {
         return false;
       }
     }
   };
   File[] files = f.listFiles(textFilter);
   for (File file : files)
   {
     if (file.isDirectory())
     {
       System.out.print("directory:");
     }
     else
     {
       System.out.print("   file:");
     }
     System.out.println(file.getCanonicalPath());
   }
 }
}

$post_ =array (
 'author' => 'Gonn',
 'mail'=>'gonn@nowamagic.net',
 'url'=>'http://www.nowamagic.net/',
 'text'=>'欢迎访问简明现代魔法');
$data=http_build_query($post_);
$fp = fsockopen("nowamagic.net", 80, $errno, $errstr, 5);
$out="POST http://nowamagic.net/news/1/comment HTTP/1.1\r\n";
$out.="Host: typecho.org\r\n";
$out.="User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; zh-CN; rv:1.9.2.13) Gecko/20101203 Firefox/3.6.13"."\r\n";
$out.="Content-type: application/x-www-form-urlencoded\r\n";
$out.="PHPSESSID=082b0cc33cc7e6df1f87502c456c3eb0\r\n";
$out.="Content-Length: " . strlen($data) . "\r\n";
$out.="Connection: close\r\n\r\n";
$out.=$data."\r\n\r\n";
fwrite($fp, $out);
while (!feof($fp))
{
 echo fgets($fp, 1280);
}
fclose($fp);

$opts = array (
 'http'=>array(
   'method' => 'POST',
   'header'=> "Content-type: application/x-www-form-urlencoded\r\n" .
        "Content-Length: " . strlen($data) . "\r\n",
   'content' => $data)
);
$context = stream_context_create($opts);
file_get_contents('http://nowamagic.net/news/1/comment', false, $context);

$fp = fopen('c:/test.txt', 'w+');
/* 把rot13过滤器作用在写入流上 */
stream_filter_append($fp, "string.rot13", STREAM_FILTER_WRITE);
/* 写入的数据经过rot13过滤器的处理*/
fwrite($fp, "This is a test\n");
rewind($fp);
/* 读取写入的数据，独到的自然是被处理过的字符了 */
fpassthru($fp);
fclose($fp);
// output：Guvf vf n grfg

$streamlist = stream_get_filters();
print_r($streamlist);

Array
(
 [0] => convert.iconv.*
 [1] => mcrypt.*
 [2] => mdecrypt.*
 [3] => string.rot13
 [4] => string.toupper
 [5] => string.tolower
 [6] => string.strip_tags
 [7] => convert.*
 [8] => consumed
 [9] => dechunk
 [10] => zlib.*
 [11] => bzip2.*
)

class md5_filter extends php_user_filter
{
 function filter($in, $out, &$consumed, $closing)
 {
   while ($bucket = stream_bucket_make_writeable($in))
   {
     $bucket->data = md5($bucket->data);
     $consumed += $bucket->datalen;
     stream_bucket_append($out, $bucket);
   }
   //数据处理成功，可供其它管道读取
   return PSFS_PASS_ON;
 }
}
stream_filter_register("string.md5", "md5_filter");

class md5_filter extends php_user_filter
{
 public function filter($in, $out, &$consumed, $closing)
 {
   $data="";
   while ($bucket = stream_bucket_make_writeable($in))
   {
     $bucket->data = md5($bucket->data);
     $consumed += $bucket->datalen;
     stream_bucket_append($out, $bucket);
   }
   call_user_func($this->params, $data);
   return PSFS_PASS_ON;
 }
}
$callback = function($data)
{
 file_put_contents("c:\log.txt",date("Y-m-d H:i")."\r\n");
};