一切对header()函数有懂得的人都晓得，这个函数会发送一段文件头给阅读器，然而假如在利用这个函数之前已有了任何输入（包含空输入，好比空格，回车和换行）就会提醒失足。假如咱们去失落第一行的ob_start()，再履行此法式，咱们会发明失掉了一条毛病提醒：“Header had all ready send by”！然而加上ob_start，就不会提醒失足，缘由是当翻开了缓冲区，echo前面的字符不会输入到阅读器，而是保存在办事器，直到你利用flush或ob_end_flush才会输入，所以其实不会有任何文件头输入的毛病！
详细后果你可以到这里看看http://www.php2000.com/~uchinaboy/out.php
PHP2000的最新的PHP聊天室就是用的这个手艺，惋惜的是源代码未公然 L
注：假如在法式的首部到场ob_implicit_flush()翻开相对刷新,就能够在法式中不再利用flush(),如许做的优点是：进步效力！
<?
/*
** Title.........: PHP4 HTTP Compression Speeds up the Web
** Version.......: 1.20
** Author........: catoc <catoc@163.net>
** Filename......: gzdoc.php
** Last changed..: 18/10/2000
** Requirments...: PHP4 >= 4.0.1
** PHP was configured with --with-zlib[=DIR]
** Notes.........: Dynamic Content Acceleration compresses
** the data transmission data on the fly
** code by sun jin hu (catoc) <catoc@163.net>
** Most newer browsers since 1998/1999 have
** been equipped to support the HTTP 1.1
** standard known as "content-encoding."
** Essentially the browser indicates to the
** server that it can accept "content encoding"
** and if the server is capable it will then
** compress the data and transmit it. The
** browser decompresses it and then renders
** the page.
**
** Modified by John Lim (jlim@natsoft.com.my)
** based on ideas by Sandy McArthur, Jr
** Usage........:
** No space before the beginning of the first '<?' tag.
** ------------Start of file----------
** |<?
** | include('gzdoc.php');
** |? >
** |<HTML>
** |... the page ...
** |</HTML>
** |<?
** | gzdocout();
** |? >
** -------------End of file-----------
*/
ob_start();
ob_implicit_flush(0);
function CheckCanGzip(){
global $HTTP_ACCEPT_ENCODING;
if (headers_sent() || connection_timeout() || connection_aborted()){
return 0;
}
if (strpos($HTTP_ACCEPT_ENCODING, 'x-gzip') !== false) return "x-gzip";
if (strpos($HTTP_ACCEPT_ENCODING,'gzip') !== false) return "gzip";
return 0;
}
/* $level = compression level 0-9, 0=none, 9=max */
function GzDocOut($level=1,$debug=0){
$ENCODING = CheckCanGzip();
if ($ENCODING){
print "n<!-- Use compress $ENCODING -->n";
$Contents = ob_get_contents();
ob_end_clean();
if ($debug){
$s = "<p>Not compress length: ".strlen($Contents);
$s .= "
Compressed length: ".strlen(gzcompress($Contents,$level));
$Contents .= $s;
}
header("Content-Encoding: $ENCODING");
print "x1fx8bx08x00x00x00x00x00";
$Size = strlen($Contents);
$Crc = crc32($Contents);
$Contents = gzcompress($Contents,$level);
$Contents = substr($Contents, 0, strlen($Contents) - 4);
print $Contents;
print pack('V',$Crc);
print pack('V',$Size);
exit;
}else{
ob_end_flush();
exit;
}
}
?>