blocks|key|224459|text|试一试|type|unstyled|depth|inlineStyleRanges|entityRanges|data|224460|<?php
++++if(!isset($_SESSION))+
++++{+
++++++++session_start();+
++++}+
?>|code-block|syntax|javascript|224461|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Try

<pre><code>&lt;?php
 if(!isset($_SESSION)) 
 { 
 session_start(); 
 } 
?&gt;
</code></pre>

blocks|key|3096827|text|仅当您想要销毁前一个会话时才使用+:|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|3096828|<?php
++++if(!isset($_SESSION))+
++++{+
++++++++session_start();+
++++}
++++else
++++{
++++++++session_destroy();
++++++++session_start();+
++++}
?>|code-block|syntax|javascript|3096829|，或者您可以使用|3096830|unset($_SESSION['variable_session+_data'])|3096831|用于销毁特定会话变量的。|3096832|entityMap^0|G|2|0|0|0|8|0|0|B|1|0^^$0|@$1|2|3|4|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|M|3|N|5|H|7|Z|8|@]|D|@]|E|$I|J]]|$1|O|3|P|5|6|7|10|8|@$9|11|A|12|B|C]]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|13|8|@]|D|@]|E|$]]]|R|$]]

Only if you want to destroy previous session :

<pre><code>&lt;?php
 if(!isset($_SESSION)) 
 { 
 session_start(); 
 }
 else
 {
 session_destroy();
 session_start(); 
 }
?&gt;
</code></pre>

or you can use

<pre><code>unset($_SESSION['variable_session _data'])
</code></pre>

to destroy a particular session variable.

blocks|key|3097155|text|session_status()+===+PHP_SESSION_ACTIVE+?:+session_start();|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|3097156|封闭式游戏|unstyled|3097157|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>session_status() === PHP_SESSION_ACTIVE ?: session_start();
</code></pre>

Closed Game

blocks|key|2882960|text|可以，您可以通过检查isset($_SESSION)来检测会话是否已在运行。然而，最好的答案就是不要多次调用session_start()。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2882961|应该在脚本中很早就调用它，甚至可能是第一行，然后再也不调用。|2882962|如果你在你的代码中不止一个地方有它，那么你就是在要求得到这类bug。减少它，使其只出现在一个位置，并且只能调用一次。|2882963|entityMap^0|A|G|1I|F|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@$9|M|A|N|B|C]|$9|O|A|P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Q|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|R|8|@]|D|@]|E|$]]|$1|J|3|-4|5|6|7|S|8|@]|D|@]|E|$]]]|K|$]]

Yes, you can detect if the session is already running by checking <code>isset($_SESSION)</code>. However the best answer is simply not to call <code>session_start()</code> more than once.

It should be called very early in your script, possibly even the first line, and then not called again.

If you have it in more than one place in your code then you're asking to get this kind of bug. Cut it down so it's only in one place and can only be called once.

blocks|key|228137|text|您一定已经调用了会话start，可能会通过include再次被调用？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|228138|if(+!+$_SESSION)
{
++++session_start();
}++|code-block|syntax|javascript|228139|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You must of already called the session start maybe being called again through an include?

<pre><code>if( ! $_SESSION)
{
 session_start();
} 
</code></pre>

blocks|key|224640|text|我在尝试修复$_SESSION的阻塞行为时遇到了这个问题。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|224641|http://konrness.com/php5/how-to-prevent-blocking-php-requests/|offset|length|224642|224643|在脚本完成或手动关闭会话之前，会话文件将保持锁定状态。|blockquote|224644|224645|224646|因此，默认情况下，页面应以只读模式打开会话。但一旦它以只读模式打开，就必须在中关闭并重新打开才能进入写入模式。|224647|const+SESSION_DEFAULT_COOKIE_LIFETIME+=+86400;

/**
+*+Open+_SESSION+read-only
+*/
function+OpenSessionReadOnly()+{
++++session_start([
++++++++++++++++++++++'cookie_lifetime'+=>+SESSION_DEFAULT_COOKIE_LIFETIME,
++++++++++++++++++++++'read_and_close'++=>+true,++++//+READ+ACCESS+FAST
++++++++++++++++++]);
++++//+$_SESSION+is+now+defined.+Call+WriteSessionValues()+to+write+out+values
}

/**
+*+_SESSION+is+read-only+by+default.+Call+this+function+to+save+a+new+value
+*+call+this+function+like+`WriteSessionValues(["username"=>$login_user]);`
+*+to+set+$_SESSION["username"]
+*
+*+@param+array+$values_assoc_array
+*/
function+WriteSessionValues($values_assoc_array)+{
++++//+this+is+required+to+close+the+read-only+session+and+
++++//+not+get+a+warning+on+the+next+line.
++++session_abort();

++++//+now+open+the+session+with+write+access
++++session_start([+'cookie_lifetime'+=>+SESSION_DEFAULT_COOKIE_LIFETIME+]);

++++foreach+($values_assoc_array+as+$key+=>+$value)+{
++++++++$_SESSION[+$key+]+=+$value;
++++}
++++session_write_close();++//+Write+session+data+and+end+session

++++OpenSessionReadOnly();+//+now+reopen+the+session+in+read-only+mode.
}

OpenSessionReadOnly();++//+start+the+session+for+this+page|code-block|syntax|javascript|224648|然后当你要写一些值的时候：|224649|WriteSessionValues(["username"=>$login_user]);|224650|该函数接受一组key=>value对，以使其更加高效。|224651|entityMap|0|LINK|mutability|MUTABLE|url^0|0|0|1Q|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|15|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|16|8|@]|9|@$D|17|E|18|1|19]]|A|$]]|$1|F|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|G|3|H|5|I|7|1B|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|1E|8|@]|9|@]|A|$]]|$1|N|3|O|5|P|7|1F|8|@]|9|@]|A|$Q|R]]|$1|S|3|T|5|6|7|1G|8|@]|9|@]|A|$]]|$1|U|3|V|5|P|7|1H|8|@]|9|@]|A|$Q|R]]|$1|W|3|X|5|6|7|1I|8|@]|9|@]|A|$]]|$1|Y|3|-4|5|6|7|1J|8|@]|9|@]|A|$]]]|Z|$10|$5|11|12|13|A|$14|C]]]]

I encountered this issue while trying to fix $_SESSION's blocking behavior.

<a href="http://konrness.com/php5/how-to-prevent-blocking-php-requests/" rel="nofollow noreferrer">http://konrness.com/php5/how-to-prevent-blocking-php-requests/</a>

<blockquote>
 The session file remains locked until the script completes or the
 session is manually closed.
</blockquote>

So, by default, a page should open a session in read-only mode. But once it's open in read-only, it has to be closed-and-reopened in to get it into write mode.

<pre><code>const SESSION_DEFAULT_COOKIE_LIFETIME = 86400;

/**
 * Open _SESSION read-only
 */
function OpenSessionReadOnly() {
 session_start([
 'cookie_lifetime' =&gt; SESSION_DEFAULT_COOKIE_LIFETIME,
 'read_and_close' =&gt; true, // READ ACCESS FAST
 ]);
 // $_SESSION is now defined. Call WriteSessionValues() to write out values
}

/**
 * _SESSION is read-only by default. Call this function to save a new value
 * call this function like `WriteSessionValues(["username"=&gt;$login_user]);`
 * to set $_SESSION["username"]
 *
 * @param array $values_assoc_array
 */
function WriteSessionValues($values_assoc_array) {
 // this is required to close the read-only session and 
 // not get a warning on the next line.
 session_abort();

 // now open the session with write access
 session_start([ 'cookie_lifetime' =&gt; SESSION_DEFAULT_COOKIE_LIFETIME ]);

 foreach ($values_assoc_array as $key =&gt; $value) {
 $_SESSION[ $key ] = $value;
 }
 session_write_close(); // Write session data and end session

 OpenSessionReadOnly(); // now reopen the session in read-only mode.
}

OpenSessionReadOnly(); // start the session for this page
</code></pre>

Then when you go to write some value:

<pre><code>WriteSessionValues(["username"=&gt;$login_user]);
</code></pre>

The function takes an array of key=>value pairs to make it even more efficient.

blocks|key|2883149|text|只需使用if语句|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2883150|+if(!isset($_SESSION))+
+++++{+
+++++++++session_start();+
+++++}|code-block|syntax|javascript|2883151|或|offset|length|style|BOLD|2883152|使用返回当前会话状态的session_status检查会话状态，如果当前会话已经在工作，则不返回任何其他内容，如果会话不工作，则启动会话|2883153|session_status()+===+PHP_SESSION_ACTIVE+?:+session_start();|2883154|entityMap^0|0|0|0|1|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@$I|V|J|W|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|X|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

Simply use if statement
<pre><code> if(!isset($_SESSION)) 
 { 
 session_start(); 
 }
</code></pre>
or
check the session status with session_status that Returns the current session status
and if current session is already working then return with nothing else if session not working start the session
<pre><code>
session_status() === PHP_SESSION_ACTIVE ?: session_start();
</code></pre>

blocks|key|227471|text|<?php
if+(+session_id()+!=+""+)+{
++++session_start();
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|227472|基本上，在创建另一个会话之前，您需要检查会话是否已启动；.|unstyled|offset|length|227473|另一方面，您选择在使用session_destroy()创建另一个会话之前销毁现有会话。|style|CODE|227474|entityMap|0|LINK|mutability|MUTABLE|url|https://php.net/manual/en/function.session-id.php|1|https://www.php.net/manual/en/function.session-destroy.php^0|0|S|1|0|0|B|H|B|H|1|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|X|8|@]|9|@$G|Y|H|Z|1|10]]|A|$]]|$1|I|3|J|5|F|7|11|8|@$G|12|H|13|K|L]]|9|@$G|14|H|15|1|16]]|A|$]]|$1|M|3|-4|5|F|7|17|8|@]|9|@]|A|$]]]|N|$O|$5|P|Q|R|A|$S|T]]|U|$5|P|Q|R|A|$S|V]]]]

<pre><code>&lt;?php
if ( session_id() != "" ) {
 session_start();
}
</code></pre>

Basically, you need to check if a session was started before creating another one; <a href="https://php.net/manual/en/function.session-id.php" rel="nofollow noreferrer">... more reading.</a>

On the other hand, you chose to destroy an existing session before creating another one using <a href="https://www.php.net/manual/en/function.session-destroy.php" rel="nofollow noreferrer"><code>session_destroy()</code></a>.

blocks|key|3096933|text|尝尝这个|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3096934|if(!isset($_SESSION)){+
++++session_start();
}|code-block|syntax|javascript|3096935|我建议您使用ob_start()；在启动任何可用会话之前，这应该为您的浏览器缓冲区排序。|3096936|编辑:在$_SESSION后面添加了额外的)|3096937|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

try this

<pre><code>if(!isset($_SESSION)){ 
 session_start();
}
</code></pre>

I suggest you to use ob_start(); before starting any sesson varriable, this should order you browser buffer.

edit: Added an extra ) after $_SESSION

blocks|key|3097029|text|如果不在所有依赖于$Session变量的php文件中调用session_start()，上述方法都不适用。通知太烦人了，很快就把Error_log填满了。我能找到的唯一有效的解决方案是……|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3097030|++++error_reporting(E_ALL+%5E+E_NOTICE);
++++session_start();|code-block|syntax|javascript|3097031|一个坏的修复，但它是有效的。|3097032|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

None of the above was suitable, without calling session_start() in all php files that depend on $Session variables they will not be included. The Notice is so annoying and quickly fill up the Error_log. The only solution that I can find that works is this....

<pre><code> error_reporting(E_ALL ^ E_NOTICE);
 session_start();
</code></pre>

A Bad fix , but it works.

blocks|key|3097139|text|这样效率会更高：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3097140|@session_start();|code-block|syntax|javascript|3097141|避免屏幕中的错误处理程序|3097142|最好的|3097143|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

It would be more efficient:

<pre><code>@session_start();
</code></pre>

Avoiding error handler in the screen

Best,

In my PHP code, if a session has already started, and I try to start a new one, I get the following Notice:

<blockquote>
 Notice: A session had already been started - ignoring session_start()
</blockquote>

How can I avoid this?

PHP sessions that have already been started

在我的PHP代码中，如果一个会话已经启动，并且我尝试启动一个新的会话，我会收到以下通知：通知:会话已启动-忽略session_start()我怎样才能避免这种情况？

问已经启动的PHP会话
EN

回答 11

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问已经启动的PHP会话EN

回答 11

Stack Overflow用户

Stack Overflow用户

Stack Overflow用户

社区

活动

资源

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问已经启动的PHP会话
EN