php中ob_get_contents();ob_end_clean();ob_start();用法详解

php缓存相关函数： ob_get_contents(); ob_end_clean(); ob_start()

使用ob_start()把输出那同输出到缓冲区，而不是到浏览器。 然后用ob_get_contents得到缓冲区的数据。

ob_start()在服务器打开一个缓冲区来保存所有的输出。 因此，在任何时候使用echo ，输出都将被加入缓冲区中，直到程序运行结束或者使用ob_flush()来结束。 然后在服务器中缓冲区的内容才会发送到浏览器，由浏览器来解析显示。

函数ob_end_clean 会清除缓冲区的内容，并将缓冲区关闭，但不会输出内容。 此时得用一个函数ob_get_contents()在ob_end_clean()前面来获得缓冲区的内容。 这样的话，能将在执行ob_end_clean()前把内容保存到一个变量中，然后在ob_end_clean()后面对这个变量做操作。

例子：

';
echo $buf2;
?>

下面来看，ob_get_contents

(PHP 4, PHP 5) ob_get_contents -- Return the contents of the output buffer Description string ob_get_contents ( void )

This will return the contents of the output buffer or FALSE, if output buffering isn't active.

See also ob_start() and ob_get_length().

if you use ob_start with a callback function as a parameter, and that function changes ob string (as in example in manual) don't expect that ob_get_contents will return changed ob. it will work as you would use ob_start with no parameter at all. So don't be confused. transfer image, another method (alternative to fsockopen or function socket) :

server(192.168.0.1) makeimage.php

';
?>

naturally you can transfer whichever thing and not only images

ob_get_clean

(PHP 4 >= 4.3.0, PHP 5) ob_get_clean -- Get current buffer contents and delete current output buffer Description string ob_get_clean ( void )

This will return the contents of the output buffer and end output buffering. If output buffering isn't active then FALSE is returned. ob_get_clean() essentially executes both ob_get_contents() and ob_end_clean().

例1： ob_get_clean()的简单示例

输出: string(11) "hello world"

例2，ob_start() and ob_get_contents(). Notice that the function beneath does not catch errors, so throw in an @ before those ob_* calls Running PHP4 < 4.3.0, you can simply add the following to use the function anyway: