PHP文件缓存内容保存格式主要有三种：
1.变量 var_export 格式化成PHP正常的赋值书写格式，用的时候直接include文件
2.变量 serialize 序列化之后保存，用的时候反序列化
3，变量 json_encode格式化之后保存，用的时候json_decode
一直以来，我都以为第一种效率最高，因为那是PHP脚本解释器解析PHP脚本的格式，原生的，应该最快，至少读取缓存的效率应该是最高的，可是今天做了个测试，令我大跌眼镜！原来 serialize序列化效率才是最高的，不论是读还是写！
下面是用来测试的PHP文件缓存的代码：
<ol class="dp-xml">
<li class="alt"><span><span>view plaincopy to clipboardprint? </span></span></li>
<li>
<span>$</span><span class="attribute">st</span><span> = </span><span class="attribute-value">microtime</span><span>(1); </span>
</li>
<li class="alt">
<span>for ($</span><span class="attribute">i</span><span>=</span><span class="attribute-value">0</span><span>;$i</span><span class="tag"><span class="tag-name">1000</span><span>;$i++){ </span></span>
</li>
<li><span>/* </span></li>
<li class="alt">
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">var_export</span><span>($_SERVER,1); </span>
</li>
<li>
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">""</span><span>; </span>
</li>
<li class="alt"><span>file_put_contents("data/in.php",$file); </span></li>
<li><span>*/ </span></li>
<li class="alt"><span>include("data/in.php"); </span></li>
<li><span>} </span></li>
<li class="alt"><span>echo "include读:".(microtime(1)-$st)." "; </span></li>
<li>
<span>$</span><span class="attribute">st</span><span> = </span><span class="attribute-value">microtime</span><span>(1); </span>
</li>
<li class="alt">
<span>for ($</span><span class="attribute">i</span><span>=</span><span class="attribute-value">0</span><span>;$i</span><span class="tag"><span class="tag-name">1000</span><span>;$i++){ </span></span>
</li>
<li>
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_put_contents</span><span>("data/se.php" </span>
</li>
<li class="alt"><span>,serialize($_SERVER)); </span></li>
<li>
<span>//$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_get_contents</span><span>("data/se.php"); </span>
</li>
<li class="alt">
<span>//$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">unserialize</span><span>($file); </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>echo "serialize写:".(microtime(1)-$st)." "; </span></li>
<li>
<span>$</span><span class="attribute">st</span><span> = </span><span class="attribute-value">microtime</span><span>(1); </span>
</li>
<li class="alt">
<span>for ($</span><span class="attribute">i</span><span>=</span><span class="attribute-value">0</span><span>;$i</span><span class="tag"><span class="tag-name">1000</span><span>;$i++){ </span></span>
</li>
<li>
<span>//$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_put_contents</span><span>("data/se. </span>
</li>
<li class="alt"><span>php",serialize($_SERVER)); </span></li>
<li>
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_get_contents</span><span>("data/se.php"); </span>
</li>
<li class="alt">
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">unserialize</span><span>($file); </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>echo "serialize读:".(microtime(1)-$st)." "; </span></li>
<li>
<span>$</span><span class="attribute">st</span><span> = </span><span class="attribute-value">microtime</span><span>(1); </span>
</li>
<li class="alt">
<span>for ($</span><span class="attribute">i</span><span>=</span><span class="attribute-value">0</span><span>;$i</span><span class="tag"><span class="tag-name">1000</span><span>;$i++){ </span></span>
</li>
<li>
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_put_contents</span><span>("data/js.php </span>
</li>
<li class="alt"><span>",json_encode($_SERVER)); </span></li>
<li>
<span>//$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_get_contents</span><span>("data/js.php"); </span>
</li>
<li class="alt">
<span>//$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">json_decode</span><span>($file); </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>echo "json写:".(microtime(1)-$st)." "; </span></li>
<li>
<span>$</span><span class="attribute">st</span><span> = </span><span class="attribute-value">microtime</span><span>(1); </span>
</li>
<li class="alt">
<span>for ($</span><span class="attribute">i</span><span>=</span><span class="attribute-value">0</span><span>;$i</span><span class="tag"><span class="tag-name">1000</span><span>;$i++){ </span></span>
</li>
<li>
<span>//$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_put_contents</span><span>("data/js. </span>
</li>
<li class="alt"><span>php",json_encode($_SERVER)); </span></li>
<li>
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_get_contents</span><span>("data/js.php"); </span>
</li>
<li class="alt">
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">json_decode</span><span>($file); </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>echo "json读:".(microtime(1)-$st)." "; </span></li>
<li>
<span>$</span><span class="attribute">st</span><span> = </span><span class="attribute-value">microtime</span><span>(1); </span>
</li>
<li class="alt">
<span>for ($</span><span class="attribute">i</span><span>=</span><span class="attribute-value">0</span><span>;$i</span><span class="tag"><span class="tag-name">1000</span><span>;$i++){ </span></span>
</li>
<li><span>/* </span></li>
<li class="alt">
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">var_export</span><span>($_SERVER,1); </span>
</li>
<li>
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">""</span><span>; </span>
</li>
<li class="alt"><span>file_put_contents("data/in.php",$file); </span></li>
<li><span>*/ </span></li>
<li class="alt"><span>include("data/in.php"); </span></li>
<li><span>} </span></li>
<li class="alt"><span>echo "include读:".(microtime(1)-$st)." "; </span></li>
<li>
<span>$</span><span class="attribute">st</span><span> = </span><span class="attribute-value">microtime</span><span>(1); </span>
</li>
<li class="alt">
<span>for ($</span><span class="attribute">i</span><span>=</span><span class="attribute-value">0</span><span>;$i</span><span class="tag"><span class="tag-name">1000</span><span>;$i++){ </span></span>
</li>
<li>
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_put_contents</span><span>("data/se. </span>
</li>
<li class="alt"><span>php",serialize($_SERVER)); </span></li>
<li>
<span>//$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_get_contents</span><span>("data/se.php"); </span>
</li>
<li class="alt">
<span>//$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">unserialize</span><span>($file); </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>echo "serialize写:".(microtime(1)-$st)." "; </span></li>
<li>
<span>$</span><span class="attribute">st</span><span> = </span><span class="attribute-value">microtime</span><span>(1); </span>
</li>
<li class="alt">
<span>for ($</span><span class="attribute">i</span><span>=</span><span class="attribute-value">0</span><span>;$i</span><span class="tag"><span class="tag-name">1000</span><span>;$i++){ </span></span>
</li>
<li>
<span>//$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_put_contents</span><span>("data/se. </span>
</li>
<li class="alt"><span>php",serialize($_SERVER)); </span></li>
<li>
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_get_contents</span><span>("data/se.php"); </span>
</li>
<li class="alt">
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">unserialize</span><span>($file); </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>echo "serialize读:".(microtime(1)-$st)." "; </span></li>
<li>
<span>$</span><span class="attribute">st</span><span> = </span><span class="attribute-value">microtime</span><span>(1); </span>
</li>
<li class="alt">
<span>for ($</span><span class="attribute">i</span><span>=</span><span class="attribute-value">0</span><span>;$i</span><span class="tag"><span class="tag-name">1000</span><span>;$i++){ </span></span>
</li>
<li>
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_put_contents</span><span>("data/js. </span>
</li>
<li class="alt"><span>php",json_encode($_SERVER)); </span></li>
<li>
<span>//$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_get_contents</span><span>("data/js.php"); </span>
</li>
<li class="alt">
<span>//$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">json_decode</span><span>($file); </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>echo "json写:".(microtime(1)-$st)." "; </span></li>
<li>
<span>$</span><span class="attribute">st</span><span> = </span><span class="attribute-value">microtime</span><span>(1); </span>
</li>
<li class="alt">
<span>for ($</span><span class="attribute">i</span><span>=</span><span class="attribute-value">0</span><span>;$i</span><span class="tag"><span class="tag-name">1000</span><span>;$i++){ </span></span>
</li>
<li>
<span>//$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_put_contents</span><span>("data/js. </span>
</li>
<li class="alt"><span>php",json_encode($_SERVER)); </span></li>
<li>
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">file_get_contents</span><span>("data/js.php"); </span>
</li>
<li class="alt">
<span>$</span><span class="attribute">file</span><span> = </span><span class="attribute-value">json_decode</span><span>($file); </span>
</li>
<li><span>} </span></li>
<li class="alt"><span>echo "json读:".(microtime(1)-$st)." "; </span></li>
</ol>结果太神奇了！include写:0.559882879257include读:0.185745000839serialize写:0.255033969879serialize读:0.0853068828583json写:0.284864902496json读:0.145938873291 序列化是最快，无论读或写，都是第一种的效率的两倍，json比序列化的PHP文件缓存效率稍低，表现还可以！
如果撇开文件读写所耗费的时间，他们的效率差别可能会更大！include那个，虽然是PHP脚本赋值的格式，但是也是要分析解析文本，PHP脚本解释器需要动用整个解释器分析PHP脚本，而序列化不需要，只用启用序列化文本分析就行了，所以PHP文件缓存效率更高。
