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。
代码如下：
<?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;}?>代码演示：
1、创建测试数据表
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 startStarting 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。
以上这篇php PDO判断连接是否可用的实现方法就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持网页设计。
