function.session-set-save-handler.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>Sets user-level session storage functions</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.session-set-cookie-params.html">session_set_cookie_params</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.session-start.html">session_start</a></div> <div class="up"><a href="ref.session.html">Session Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.session-set-save-handler" class="refentry"> <div class="refnamediv"> <h1 class="refname">session_set_save_handler</h1> <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">session_set_save_handler</span> — <span class="dc-title">Sets user-level session storage functions</span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">bool</span> <span class="methodname"><b><b>session_set_save_handler</b></b></span> ( <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.callback" class="type callback">callback</a></span> <tt class="parameter">$open</tt></span> , <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.callback" class="type callback">callback</a></span> <tt class="parameter">$close</tt></span> , <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.callback" class="type callback">callback</a></span> <tt class="parameter">$read</tt></span> , <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.callback" class="type callback">callback</a></span> <tt class="parameter">$write</tt></span> , <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.callback" class="type callback">callback</a></span> <tt class="parameter">$destroy</tt></span> , <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.callback" class="type callback">callback</a></span> <tt class="parameter">$gc</tt></span> )</div> <p class="para rdfs-comment"> <b>session_set_save_handler()</b> sets the user-level session storage functions which are used for storing and retrieving data associated with a session. This is most useful when a storage method other than those supplied by PHP sessions is preferred. i.e. Storing the session data in a local database. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">open</tt></i></span> <dd> <p class="para"> Open function, this works like a constructor in classes and is executed when the session is being opened. The open function expects two parameters, where the first is the save path and the second is the session name. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">close</tt></i></span> <dd> <p class="para"> Close function, this works like a destructor in classes and is executed when the session operation is done. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">read</tt></i></span> <dd> <p class="para"> Read function must return string value always to make save handler work as expected. Return empty string if there is no data to read. Return values from other handlers are converted to boolean expression. <b><tt>TRUE</tt></b> for success, <b><tt>FALSE</tt></b> for failure. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">write</tt></i></span> <dd> <p class="para"> <blockquote><p><b class="note">Note</b>: The "write" handler is not executed until after the output stream is closed. Thus, output from debugging statements in the "write" handler will never be seen in the browser. If debugging output is necessary, it is suggested that the debug output be written to a file instead. <br /> </p></blockquote> </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">destroy</tt></i></span> <dd> <p class="para"> The destroy handler, this is executed when a session is destroyed with <a href="function.session-destroy.html" class="function">session_destroy()</a> and takes the session id as its only parameter. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">gc</tt></i></span> <dd> <p class="para"> The garbage collector, this is executed when the session garbage collector is executed and takes the max session lifetime as its only parameter. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns <b><tt>TRUE</tt></b> on success or <b><tt>FALSE</tt></b> on failure. </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 <b>session_set_save_handler()</b> example</b></p> <div class="example-contents"><p> The following example provides file based session storage similar to the PHP sessions default save handler <i><tt class="parameter">files</tt></i>. This example could easily be extended to cover database storage using your favorite PHP supported database engine. </p></div> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">open</span><span style="color: #007700">(</span><span style="color: #0000BB">$save_path</span><span style="color: #007700">, </span><span style="color: #0000BB">$session_name</span><span style="color: #007700">)<br />{<br /> global </span><span style="color: #0000BB">$sess_save_path</span><span style="color: #007700">;<br /><br /> </span><span style="color: #0000BB">$sess_save_path </span><span style="color: #007700">= </span><span style="color: #0000BB">$save_path</span><span style="color: #007700">;<br /> return(</span><span style="color: #0000BB">true</span><span style="color: #007700">);<br />}<br /><br />function </span><span style="color: #0000BB">close</span><span style="color: #007700">()<br />{<br /> return(</span><span style="color: #0000BB">true</span><span style="color: #007700">);<br />}<br /><br />function </span><span style="color: #0000BB">read</span><span style="color: #007700">(</span><span style="color: #0000BB">$id</span><span style="color: #007700">)<br />{<br /> global </span><span style="color: #0000BB">$sess_save_path</span><span style="color: #007700">;<br /><br /> </span><span style="color: #0000BB">$sess_file </span><span style="color: #007700">= </span><span style="color: #DD0000">"$sess_save_path/sess_$id"</span><span style="color: #007700">;<br /> return (string) @</span><span style="color: #0000BB">file_get_contents</span><span style="color: #007700">(</span><span style="color: #0000BB">$sess_file</span><span style="color: #007700">);<br />}<br /><br />function </span><span style="color: #0000BB">write</span><span style="color: #007700">(</span><span style="color: #0000BB">$id</span><span style="color: #007700">, </span><span style="color: #0000BB">$sess_data</span><span style="color: #007700">)<br />{<br /> global </span><span style="color: #0000BB">$sess_save_path</span><span style="color: #007700">;<br /><br /> </span><span style="color: #0000BB">$sess_file </span><span style="color: #007700">= </span><span style="color: #DD0000">"$sess_save_path/sess_$id"</span><span style="color: #007700">;<br /> if (</span><span style="color: #0000BB">$fp </span><span style="color: #007700">= @</span><span style="color: #0000BB">fopen</span><span style="color: #007700">(</span><span style="color: #0000BB">$sess_file</span><span style="color: #007700">, </span><span style="color: #DD0000">"w"</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$return </span><span style="color: #007700">= </span><span style="color: #0000BB">fwrite</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #0000BB">$sess_data</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">fclose</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">);<br /> return </span><span style="color: #0000BB">$return</span><span style="color: #007700">;<br /> } else {<br /> return(</span><span style="color: #0000BB">false</span><span style="color: #007700">);<br /> }<br /><br />}<br /><br />function </span><span style="color: #0000BB">destroy</span><span style="color: #007700">(</span><span style="color: #0000BB">$id</span><span style="color: #007700">)<br />{<br /> global </span><span style="color: #0000BB">$sess_save_path</span><span style="color: #007700">;<br /><br /> </span><span style="color: #0000BB">$sess_file </span><span style="color: #007700">= </span><span style="color: #DD0000">"$sess_save_path/sess_$id"</span><span style="color: #007700">;<br /> return(@</span><span style="color: #0000BB">unlink</span><span style="color: #007700">(</span><span style="color: #0000BB">$sess_file</span><span style="color: #007700">));<br />}<br /><br />function </span><span style="color: #0000BB">gc</span><span style="color: #007700">(</span><span style="color: #0000BB">$maxlifetime</span><span style="color: #007700">)<br />{<br /> global </span><span style="color: #0000BB">$sess_save_path</span><span style="color: #007700">;<br /><br /> foreach (</span><span style="color: #0000BB">glob</span><span style="color: #007700">(</span><span style="color: #DD0000">"$sess_save_path/sess_*"</span><span style="color: #007700">) as </span><span style="color: #0000BB">$filename</span><span style="color: #007700">) {<br /> if (</span><span style="color: #0000BB">filemtime</span><span style="color: #007700">(</span><span style="color: #0000BB">$filename</span><span style="color: #007700">) + </span><span style="color: #0000BB">$maxlifetime </span><span style="color: #007700">< </span><span style="color: #0000BB">time</span><span style="color: #007700">()) {<br /> @</span><span style="color: #0000BB">unlink</span><span style="color: #007700">(</span><span style="color: #0000BB">$filename</span><span style="color: #007700">);<br /> }<br /> }<br /> return </span><span style="color: #0000BB">true</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">session_set_save_handler</span><span style="color: #007700">(</span><span style="color: #DD0000">"open"</span><span style="color: #007700">, </span><span style="color: #DD0000">"close"</span><span style="color: #007700">, </span><span style="color: #DD0000">"read"</span><span style="color: #007700">, </span><span style="color: #DD0000">"write"</span><span style="color: #007700">, </span><span style="color: #DD0000">"destroy"</span><span style="color: #007700">, </span><span style="color: #DD0000">"gc"</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">session_start</span><span style="color: #007700">();<br /><br /></span><span style="color: #FF8000">// proceed to use sessions normally<br /><br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </p> </div> <div class="refsect1 notes"> <h3 class="title">Notes</h3> <div class="warning"><b class="warning">Warning</b> <p class="para"> As of PHP 5.0.5 the <i><tt class="parameter">write</tt></i> and <i><tt class="parameter">close</tt></i> handlers are called after object destruction and therefore cannot use objects or throw exceptions. The object destructors can however use sessions. </p> <p class="para"> It is possible to call <a href="function.session-write-close.html" class="function">session_write_close()</a> from the destructor to solve this chicken and egg problem. </p> </div> <div class="warning"><b class="warning">Warning</b> <p class="para"> Current working directory is changed with some SAPIs if session is closed in the script termination. It is possible to close the session earlier with <a href="function.session-write-close.html" class="function">session_write_close()</a>. </p> </div> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"> The <a href="session.configuration.html#ini.session.save-handler" class="link">session.save_handler</a> configuration directive </li> </ul> </p> </div> </div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.session-set-cookie-params.html">session_set_cookie_params</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.session-start.html">session_start</a></div> <div class="up"><a href="ref.session.html">Session Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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