php PDO判断连接是否可用的实现方法

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;}?>