php PDO判断连接是否可用的实现方法

<?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;

insert into user(name) values('fdipzone'),('xfdipzone'),('terry');

mysql> select * from user;
+----+-----------+
| id | name   |
+----+-----------+
| 1 | fdipzone |
| 2 | xfdipzone |
| 3 | terry   |
+----+-----------+

<?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;
  }

}
?>

<?php
require '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;
}
?>

mysql.server stop
Shutting down MySQL
.... SUCCESS! 
mysql.server start
Starting MySQL
 SUCCESS! 

connect ok
Array
(
  [0] => Array
    (
      [id] => 2
      [name] => xfdipzone
    )

)
sleep 10

connect failure
Array
(
  [0] => Array
    (
      [id] => 3
      [name] => terry
    )

)
sleep 10

connect ok
Array
(
  [0] => Array
    (
      [id] => 3
      [name] => terry
    )

)
sleep 10