Php output buffering cache and program cache_PHP tutorial-PHP Tutorial-php.cn

Php output buffering cache and program cache_PHP tutorial

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Release： 2016-07-20 11:13:01

Original

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Test below

In order to make the test effect more obvious before testing, we

Output_buffering=off

Display_errors=on

Code

<strong><span 1</span> <span echo</span> "php"<span ;
</span><span 2</span> <span header</span>("content-type:text/html;charset='utf-8'"<span );
</span><span 3</span> <span echo</span> 'ok';</strong>

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will appear

php
Warning: Cannot modify header information - headers already sent by (output started at D:wwwapachehtdocstestt2.php:2) in D:wwwapachehtdocstestt2.php on line 3
ok

Code 2:

<strong><span 1</span> <span ob_start</span><span ();
</span><span 2</span> <span echo</span> "php"<span ;
</span><span 3</span> <span header</span>("content-type:text/html;charset='utf-8'"<span );
</span><span 4</span> <span echo</span> 'ok';</strong>

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The result is completely correct

Cause analysis:

CodePhpecho ‘php’ has already sent a header message to the browser,

When it appears again

header("content-type:text/html;charset='utf-8'");

I saw another header information. At this time, the above header information had been typed back. I couldn't change it and an error occurred.

When code'php', put the data to be sent to the browser first into

Look at the following code to deepen your understanding

Code

<strong><span ob_start</span><span ();
</span><span echo</span> "php"<span ;
</span><span header</span>("content-type:text/html;charset='utf-8'"<span );
</span><span echo</span> 'ok'<span ;
</span><span echo</span> '<hr/>'<span ;
</span><span $ob</span>=<span ob_get_contents</span><span ();
</span><span echo</span> <span $ob</span>;</strong>

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will output

Ob_get_contents()

Code

<strong><span 1</span> <span ob_start</span><span ();
</span><span 2</span> <span echo</span> "php"<span ;
</span><span 3</span> <span ob_clean</span>();<span //</span><span 清除缓存内容但不关闭缓存区，还能用(往里添加东西)</span>
<span 4</span> <span header</span>("content-type:text/html;charset='utf-8'"<span );
</span><span 5</span> <span echo</span> 'ok'<span ;
</span><span 6</span> <span echo</span> '<hr/>'<span ;
</span><span 7</span> <span $ob</span>=<span ob_get_contents</span><span ();
</span><span 8</span> <span echo</span> <span $ob</span>;</strong>

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Result:

Code

<strong><span ob_start</span><span ();
</span><span echo</span> "php"<span ;
</span><span ob_end_clean</span>();<span //</span><span 清空缓存内容并关闭缓存区，ob_get_contents取不到内容</span>
<span header</span>("content-type:text/html;charset='utf-8'"<span );
</span><span echo</span> 'ok'<span ;
</span><span echo</span> '<hr/>'<span ;
</span><span $ob</span>=<span ob_get_contents</span><span ();
</span><span echo</span> <span $ob</span>;</strong>

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Result:

Code

<strong><span ob_start</span><span ();
</span><span echo</span> "php"<span ;
</span><span ob_end_flush</span>();<span //</span><span 把缓存送到程序缓存内并关闭ob缓存</span>
<span header</span>("content-type:text/html;charset='utf-8'"<span );
</span><span echo</span> 'ok'<span ;
</span><span echo</span> '<hr/>'<span ;
</span><span $ob</span>=<span ob_get_contents</span><span ();
</span><span echo</span> <span $ob</span>;</strong>

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Code

<strong><span ob_start</span><span ();
</span><span echo</span> "php"<span ;
</span><span ob_flush</span>();<span //</span><span 把Ob 缓存送到程序缓存，不关闭ob缓存</span>
<span header</span>("content-type:text/html;charset='utf-8'"<span );
</span><span echo</span> 'ok'<span ;
</span><span echo</span> '<hr/>'<span ;
</span><span $ob</span>=<span ob_get_contents</span><span ();
</span><span echo</span> <span $ob</span>;</strong>

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Result:

Ob_clean()

Clear

Ob_get_flush()

Flush cache to program cache, close

Code

<strong><span Ob_start</span><span ();
</span><span echo</span> 'abc'<span ;
</span><span header</span>("content-type:text/html;charset='utf-8'"<span );
</span><span echo</span> 'hello'<span ;
</span><span Ob_flush</span><span ();
</span><span echo</span> 'aa'<span ;
</span><span echo</span> <span ob_get_contents</span><span ();
</span><span //</span><span abchelloaaaa</span></strong>

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2.ob_flush(),flush()

Code

<strong><span ob_start</span><span ();
</span><span echo</span> 'a'<span ;
</span><span flush</span>();<span //</span><span 把Ob缓存冲刷到程序缓存再冲刷到浏览器输出，不影响ob缓存</span>
<span echo</span> <span ob_get_contents</span><span ();
</span><span //</span><span aa</span></strong>

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Code

<strong><span ob_start</span><span ();
</span><span echo</span> 'a'<span ;
</span><span ob_flush</span>();<span //</span><span 把Ob缓存冲刷到程序缓存,ob里没有了缓存内容</span>
<span echo</span> "<br/>ob_con".<span ob_get_contents</span><span ();
</span><span //</span><span a     是按正常输出的，Ob里没内容</span></strong>

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代码

<strong><span echo</span> <span str_repeat</span>(" ",1024);<span //</span><span 一些版本的 Microsoft Internet Explorer 只有当接受到的256个字节以后才开始显示该页面，所以必须发送一些额外的空格来让这些浏览器显示页面内容。 </span>
<span for</span>(<span $i</span>=0;<span $i</span><5;<span $i</span>++<span ){
</span><span echo</span> <span $i</span><span ;
</span><span echo</span> "<br/>"<span ;
</span><span sleep</span>(1<span );
</span><span flush</span><span ();
}</span></strong>

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会一秒输出一个数字

如果没有