mysql_ping() 检查到服务器的连接是否正常。如果到服务器的连接可用,则返回true,否则返回false。
但PDO不支持mysql_ping()方法,因此需要自己编写代码模拟mysql_ping()方法,检查连接是否可用。
<?php/** * 检查连接是否可用 * @param Link $dbconn 数据库连接 * @return Boolean */function pdo_ping($dbconn){ try{ $dbconn->getAttribute(PDO::ATTR_SERVER_INFO); } catch (PDOException $e) { if(strpos($e->getMessage(), 'MySQL server has gone away')!==false){ return false; } } return true; }?>
CREATE TABLE `user` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(20) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
2.插入测试数据
insert into user(name) values('fdipzone'),('xfdipzone'),('terry');mysql> select * from user; +----+-----------+| id | name | +----+-----------+| 1 | fdipzone | | 2 | xfdipzone || 3 | terry | +----+-----------+
3.演示文件
db.php
<?php// 数据库操作类class DB{ // 保存数据库连接 private static $_instance = null; // 连接数据库 public static function get_conn($config){ if(isset(self::$_instance) && !empty(self::$_instance)){ return self::$_instance; } $dbhost = $config['host']; $dbname = $config['dbname']; $dbuser = $config['user']; $dbpasswd = $config['password']; $pconnect = $config['pconnect']; $charset = $config['charset']; $dsn = "mysql:host=$dbhost;dbname=$dbname;"; try { $h_param = array( PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION, ); if ($charset != '') { $h_param[PDO::MYSQL_ATTR_INIT_COMMAND] = 'SET NAMES ' . $charset; //設置默認編碼 } if ($pconnect) { $h_param[PDO::ATTR_PERSISTENT] = true; } $conn = new PDO($dsn, $dbuser, $dbpasswd, $h_param); } catch (PDOException $e) { throw new ErrorException('Unable to connect to db server. Error:' . $e->getMessage(), 31); } self::$_instance = $conn; return $conn; } // 执行查询 public static function query($dbconn, $sqlstr, $condparam){ $sth = $dbconn->prepare($sqlstr); try{ $sth->execute($condparam); } catch (PDOException $e) { echo $e->getMessage().PHP_EOL; } $result = $sth->fetchAll(PDO::FETCH_ASSOC); return $result; } // 重置连接 public static function reset_connect(){ self::$_instance = null; } }?>
test.php
<?phprequire 'db.php';// 数据库设定$config = array( 'host' => 'localhost', 'dbname' => 'user', 'user' => 'root', 'password' => '', 'pconnect' => 0, 'charset' => '');// 循环执行while(true){ // 创建数据连接 $dbconn = DB::get_conn($config); // 判断连接是否有效 $status = pdo_ping($dbconn); if($status){ echo 'connect ok'.PHP_EOL; }else{ echo 'connect failure'.PHP_EOL; // 重置连接 DB::reset_connect(); $dbconn = DB::get_conn($config); } // 执行查询 $sqlstr = 'select * from user where id=?'; $condparam = array(mt_rand(1,3)); $data = DB::query($dbconn, $sqlstr, $condparam); print_r($data); // 延时10秒 echo 'sleep 10'.PHP_EOL.PHP_EOL; sleep(10); }/** * 检查连接是否可用 * @param Link $dbconn 数据库连接 * @return Boolean */function pdo_ping($dbconn){ try{ $dbconn->getAttribute(PDO::ATTR_SERVER_INFO); } catch (PDOException $e) { if(strpos($e->getMessage(), 'MySQL server has gone away')!==false){ return false; } } return true; }?>
4.执行
在php cli模式下执行test.php,然后马上执行mysql.server stop 与 mysql.server start 模拟闪断
mysql.server stopShutting down MySQL .... SUCCESS! mysql.server start Starting MySQL SUCCESS!
执行输出:
connect okArray( [0] => Array ( [id] => 2 [name] => xfdipzone ) ) sleep 10connect failureArray( [0] => Array ( [id] => 3 [name] => terry ) ) sleep 10connect okArray( [0] => Array ( [id] => 3 [name] => terry ) ) sleep 10
可以看到闪断后,pdo_ping()返回false,连接失败,然后调用自动重连,保证后面的查询能继续执行。
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