所以我正在制作一个用户使用 facebook 登录的网页。如果用户已经登录，则页面重定向到另一个页面。但是最近我遇到了著名的 http headers already sent 错误。现在通常我知道如何解决这个问题，但我无法在我的文件中找到错误。以下是页面：
完整错误：
Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at /home/streetst/public_html/scripts/fb/fbaccess.php:1) in /home/streetst/public_html/scripts/fb/src/facebook.php on line 49
索引.php
<?php include 'scripts/fb/fbaccess.php'; ?>
<!DOCTYPE HTML>
<html>
<head>
<title>Streetstash - Streetwear, Accessories & Skateboarding, samlet på et sted</title>
<link rel="stylesheet" type="text/css" href="stylesheet.css">
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js" ></script>
<meta name='description' content='Alle dine yndlings butikker, tøj, accessories og skateboarding samlet på et sted.' />
<meta charset="utf-8">
<?php if($_GET['welcome']=='no'){?>
<script language="javascript">
window.location.href = "scripts/log_user.php"
</headersalreadscript>
<?php } ?>
<script>
$(document).ready(function() {
$('h1.title').fadeIn(1500);
$('h3.subtitle').delay(1500).fadeIn(2000);
setTimeout(function() {
$('html, body').animate({
scrollTop: $('div.sub-body').offset().top
}, 2000);
}, 4000);
});
</script>
</head>
<body>
<div class='content'>
<div class='head'>
</div>
<div class='body'>
<h1 class='title'>Streetstash</h1><br>
<h3 class='subtitle'>Streetwear, Accessories & Skateboarding</h3>
<div class='sub-body'>
<div class='title'><h2 class='title'>Streetstash</h2><br><h3 class='subsubtitle'>Streetwear, Accessories & Skateboarding</h3></div>
<div class='table'>
<div class='table_left'>
<h2>Hvad er det?</h2>
<p>Streetstash er en ny måde at handle tøj, accessories og skateboarding varer på internettet.<br><br>Streetstash samler alle de butikker du normalt handler på over internettet på et sted og tilbyder en platform, hvor du nemt og hurtigt kan finde de bedste tilbud på dine favorit varer.</p>
</div>
<div class='table_right'>
<h2>Tilmeld</h2>
<p>Støt projektet, tilmeld dig forud og modtag nyheder, opdateringer og vær klar til at shoppe de fedeste varer så snart vi åbner.</p><br>
<?php
if($user_info == null){
echo '<a href="'.$loginUrl.'"><img src="resources/img/fb_button.png"></a>';
}else{
echo '<p class="success">Tak for tilmeldingen '.$user_info['first_name'].'!</p>';
}
?>
</div>
</div>
<div class='vertline'>
</div>
</div>
</div>
</div>
</body>
</html>
/scripts/log_user.php
<?php
include 'fb/fbaccess.php';
include 'db_connect.php';
$check_query = mysql_query('SELECT * FROM users WHERE user_id = '.$user_info['id'].'');
$check_user_existence = mysql_num_rows($check_query);
echo $check_user_existence;
if($check_user_existence == 1){
echo 'User already exists';
}else{
mysql_query("INSERT INTO users (id, first_name, last_name, user_id, email) VALUES (NULL, '$user_info[first_name]', '$user_info[last_name]', '$user_info[id]', '$user_info[email]')") or die(mysql_error);
}
echo "
<script type='text/javascript'>
<!--
window.location = '../../index.php'
//-->
</script>
";
?>
/scripts/fb/fbaccess.php
<?php
//Application Configurations
$app_id = "265869100216640";
$app_secret = "47a0c95c974f6bab011824549e196bd2";
$site_url = "http://streetstash.dk/index.php?welcome=no";
try{
include_once "src/facebook.php";
}catch(Exception $e){
error_log($e);
}
// Create our application instance
$facebook = new Facebook(array(
'appId' => $app_id,
'secret' => $app_secret,
));
// Get User ID
$user = $facebook->getUser();
// We may or may not have this data based
// on whether the user is logged in.
// If we have a $user id here, it means we know
// the user is logged into
// Facebook, but we don’t know if the access token is valid. An access
// token is invalid if the user logged out of Facebook.
if($user){
//==================== Single query method ======================================
try{
// Proceed knowing you have a logged in user who's authenticated.
$user_profile = $facebook->api('/me');
}catch(FacebookApiException $e){
error_log($e);
$user = NULL;
}
//==================== Single query method ends =================================
}
if($user){
// Get logout URL
$logoutUrl = $facebook->getLogoutUrl();
}else{
// Get login URL
$loginUrl = $facebook->getLoginUrl(array(
'scope' => 'email, publish_stream, publish_actions, read_friendlists, user_location',
'redirect_uri' => $site_url,
));
}
if($user){
// Proceed knowing you have a logged in user who has a valid session.
//========= Batch requests over the Facebook Graph API using the PHP-SDK ========
// Save your method calls into an array
$queries = array(
array('method' => 'GET', 'relative_url' => '/'.$user),
array('method' => 'GET', 'relative_url' => '/'.$user.'/friends'),
);
// POST your queries to the batch endpoint on the graph.
try{
$batchResponse = $facebook->api('?batch='.json_encode($queries), 'POST');
}catch(Exception $o){
error_log($o);
}
//Return values are indexed in order of the original array, content is in ['body'] as a JSON
//string. Decode for use as a PHP array.
$user_info = json_decode($batchResponse[0]['body'], TRUE);
$friends_list = json_decode($batchResponse[1]['body'], TRUE);
//========= Batch requests over the Facebook Graph API using the PHP-SDK ends =====
}
?>
/scripts/fb/src/facebook.php
<?php
/**
* Copyright 2011 Facebook, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License. You may obtain
* a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
require_once "base_facebook.php";
/**
* Extends the BaseFacebook class with the intent of using
* PHP sessions to store user ids and access tokens.
*/
class Facebook extends BaseFacebook
{
const FBSS_COOKIE_NAME = 'fbss';
// We can set this to a high number because the main session
// expiration will trump this.
const FBSS_COOKIE_EXPIRE = 31556926; // 1 year
// Stores the shared session ID if one is set.
protected $sharedSessionID;
/**
* Identical to the parent constructor, except that
* we start a PHP session to store the user ID and
* access token if during the course of execution
* we discover them.
*
* @param Array $config the application configuration. Additionally
* accepts "sharedSession" as a boolean to turn on a secondary
* cookie for environments with a shared session (that is, your app
* shares the domain with other apps).
* @see BaseFacebook::__construct in facebook.php
*/
public function __construct($config) {
if (!session_id()) {
session_start();
}
parent::__construct($config);
if (!empty($config['sharedSession'])) {
$this->initSharedSession();
}
}
protected static $kSupportedKeys =
array('state', 'code', 'access_token', 'user_id');
protected function initSharedSession() {
$cookie_name = $this->getSharedSessionCookieName();
if (isset($_COOKIE[$cookie_name])) {
$data = $this->parseSignedRequest($_COOKIE[$cookie_name]);
if ($data && !empty($data['domain']) &&
self::isAllowedDomain($this->getHttpHost(), $data['domain'])) {
// good case
$this->sharedSessionID = $data['id'];
return;
}
// ignoring potentially unreachable data
}
// evil/corrupt/missing case
$base_domain = $this->getBaseDomain();
$this->sharedSessionID = md5(uniqid(mt_rand(), true));
$cookie_value = $this->makeSignedRequest(
array(
'domain' => $base_domain,
'id' => $this->sharedSessionID,
)
);
$_COOKIE[$cookie_name] = $cookie_value;
if (!headers_sent()) {
$expire = time() + self::FBSS_COOKIE_EXPIRE;
setcookie($cookie_name, $cookie_value, $expire, '/', '.'.$base_domain);
} else {
// @codeCoverageIgnoreStart
self::errorLog(
'Shared session ID cookie could not be set! You must ensure you '.
'create the Facebook instance before headers have been sent. This '.
'will cause authentication issues after the first request.'
);
// @codeCoverageIgnoreEnd
}
}
/**
* Provides the implementations of the inherited abstract
* methods. The implementation uses PHP sessions to maintain
* a store for authorization codes, user ids, CSRF states, and
* access tokens.
*/
protected function setPersistentData($key, $value) {
if (!in_array($key, self::$kSupportedKeys)) {
self::errorLog('Unsupported key passed to setPersistentData.');
return;
}
$session_var_name = $this->constructSessionVariableName($key);
$_SESSION[$session_var_name] = $value;
}
protected function getPersistentData($key, $default = false) {
if (!in_array($key, self::$kSupportedKeys)) {
self::errorLog('Unsupported key passed to getPersistentData.');
return $default;
}
$session_var_name = $this->constructSessionVariableName($key);
return isset($_SESSION[$session_var_name]) ?
$_SESSION[$session_var_name] : $default;
}
protected function clearPersistentData($key) {
if (!in_array($key, self::$kSupportedKeys)) {
self::errorLog('Unsupported key passed to clearPersistentData.');
return;
}
$session_var_name = $this->constructSessionVariableName($key);
unset($_SESSION[$session_var_name]);
}
protected function clearAllPersistentData() {
foreach (self::$kSupportedKeys as $key) {
$this->clearPersistentData($key);
}
if ($this->sharedSessionID) {
$this->deleteSharedSessionCookie();
}
}
protected function deleteSharedSessionCookie() {
$cookie_name = $this->getSharedSessionCookieName();
unset($_COOKIE[$cookie_name]);
$base_domain = $this->getBaseDomain();
setcookie($cookie_name, '', 1, '/', '.'.$base_domain);
}
protected function getSharedSessionCookieName() {
return self::FBSS_COOKIE_NAME . '_' . $this->getAppId();
}
protected function constructSessionVariableName($key) {
$parts = array('fb', $this->getAppId(), $key);
if ($this->sharedSessionID) {
array_unshift($parts, $this->sharedSessionID);
}
return implode('_', $parts);
}
}
真的需要这个指导！