/**
* 建立数据库链接
*
* @param $config array null代表用app config<br>
* array('host' => '127.0.0.1',
* 'port' => '3306',
* 'db' => 'test',
* 'user' => 'root',
* 'password' => '')
* @return DataBase 数据库实例
*/
public static function open($config = NULL)
{
$appDbConfig = Application::getInstance()->getConfig('db');
if (empty($config)) {
$config = $appDbConfig;
}
// 只缓存全体app公用的config
if ($config == $appDbConfig && isset(DBManager::$_db)) {
$db = DBManager::$_db;
} else {
if (class_exists('PDO')) {
$link = new \PDO('mysql:host=' . $config['host'] . ';port=' . $config['port'] . ';dbname=' . $config['db'], $config['user'], $config['password']);
if ($link->errorCode()) {
$errorInfo = $link->errorInfo();
exit("无法连接数据库：" . $errorInfo[2]);
}
DBManager::$_mode = DBManager::MODE_PDO;
$db = new DataBase($link);
} else {
if (class_exists('mysqli')) {
$link = new \mysqli($config['host'], $config['user'], $config['password'], $config['db'], $config['port']);
if ($link->connect_error) {
exit("无法连接数据库：" . $link->connect_error);
}
DBManager::$_mode = DBManager::MODE_SQLI;
$db = new DataBase($link);
} else {
$link = mysql_connect($config['host'] . ':' . $config['port'], $config['user'], $config['password']) or exit("无法连接数据库：" . mysql_error());
mysql_select_db(DB_NAME, $link) or exit("不能使用" . DB_NAME . "数据库：" . mysql_error());
DBManager::$_mode = DBManager::MODE_SQL;
$db = new DataBase($link);
}
}
// utf8改为utf8mb4，以支持一些表情符
$db->query("set names 'utf8mb4'");
if ($config == $appDbConfig) {
DBManager::$_db = $db;
}
}
return $db;
}
