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php实时输出内容

Jun 06, 2016 pm 07:55 PM
php content Can real time us output

实时输出如果放在js中我们可以直接使用settimeout来守时输入很方便,但是如果在php中实现起来就不能这样了,下面我来给介绍利用 ob_flush() 和 flush()函数实现即时实时输出内容。 一般情况下,PHP都是将整个页面全部执行完成后,才会把要输出的内容发送回客

实时输出如果放在js中我们可以直接使用settimeout来守时输入很方便,但是如果在php中实现起来就不能这样了,下面我来给介绍利用 ob_flush() 和 flush()函数实现即时实时输出内容。

 

一般情况下,PHP都是将整个页面全部执行完成后,才会把要输出的内容发送回客户端。例如有如下代码:

 

<span>for</span><span>(</span><span>$i </span><span>=</span><span>0</span><span>;</span><span> $i</span><span><span>10</span><span>;</span><span> $i</span><span>++)</span><span>{</span><span>
    echo $i</span><span>;</span><span>
    sleep</span><span>(</span><span>1</span><span>);</span><span>}</span></span>
Copy after login

 

这段代码会在10秒钟后一次性输出“0123456789”。

 

对于运行时间较长的PHP程序来说可能都需要即时输出内容来查看运行情况。

 

#设置执行时间不限时

 

<span>set_time_limit</span><span>(</span><span>0</span><span>);</span>
Copy after login

 

 

#清除并关闭缓冲,输出到浏览器之前使用这个函数

 

<span>ob_end_clean</span><span>();</span>
Copy after login

 

 

#控制隐式缓冲泻出,默认off,打开时,对每个 print/echo 或者输出命令的结果都发送到浏览器

 

<span>ob_implicit_flush</span><span>(</span><span>1</span><span>);</span>
Copy after login

 

 

这就用到了PHP的输出控制函数ob_flush()和flush()。我们把代码修改成下面这样:

 

<span>$str </span><span>=</span><span>"Hello world"</span><span>;</span><span>
echo $str </span><span>.</span><span> str_repeat</span><span>(</span><span>' '</span><span>,</span><span>256</span><span>);</span><span>
ob_flush</span><span>();</span><span>
flush</span><span>();</span><span>
sleep</span><span>(</span><span>10</span><span>);</span><span>
echo $str</span><span>;</span>
Copy after login

 

这段代码则会马上在屏幕上打印 Hello world。关键就在于第2和第3行调用的两个函数 ob_flush() 和 flush()。这两个函数得一起使用才能保证页面马上输出Hello world。其中str_repeat(' ', 256)则是为了解决某些浏览器必须在接收到256个字符后才会显示内容。

 

对上面函数升级

 

<span></span><span>php
error_reporting</span><span>(</span><span>0</span><span>);</span><span>
set_time_limit</span><span>(</span><span>0</span><span>);</span><span>
$buffer </span><span>=</span><span> ini_get</span><span>(</span><span>'output_buffering'</span><span>);</span><span>
echo str_repeat</span><span>(</span><span>' '</span><span>,</span><span> $buffer</span><span>+</span><span>1</span><span>);</span><span>
ob_end_flush</span><span>();</span><span>for</span><span>(</span><span>$i</span><span>=</span><span>1</span><span>;</span><span> $i</span><span><span>100</span><span>;</span><span> $i</span><span>++)</span><span>{</span><span>
    echo </span><span>"$i<br>"</span><span>;</span><span>
    sleep</span><span>(</span><span>1</span><span>);</span><span>
    flush</span><span>();</span><span>}</span><span>?></span></span>
Copy after login

 

这样,页面就会每一秒输出一个数字。

我们可以很方便的使用PHP的输出控制来实现页面执行进度的显示。不过,由于PHP页面有执行时间限制,而且长时间执行一个页面会对服务器造成一定的压力。


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