PHP基于单例模式编写PDO类的方法

<?php
/
  MyPDO
  @author Jason.Wei <jasonwei06@hotmail.>
  @license http://.sunbloger./
  @version 5.0 utf8
 /
class MyPDO
{
 protected static $_instance = null;
 protected $dbName = '';
 protected $dsn;
 protected $dbh;
 
 /
   构造
   
   @return MyPDO
  /
 private function __construct($dbHost, $dbUser, $dbPasswd, $dbName, $dbCharset)
 {
  try {
   $this->dsn = 'mysql:host='.$dbHost.';dbname='.$dbName;
   $this->dbh = new PDO($this->dsn, $dbUser, $dbPasswd);
   $this->dbh->exec('SET character_set_connection='.$dbCharset.', character_set_results='.$dbCharset.', character_set_client=binary');
  } catch (PDOException $e) {
   $this->outputError($e->getMessage());
  }
 }
 
 /
   防止克隆
   
  /
 private function __clone() {}
 
 /
   Singleton instance
   
   @return Object
  /
 public static function getInstance($dbHost, $dbUser, $dbPasswd, $dbName, $dbCharset)
 {
  if (self::$_instance === null) {
   self::$_instance = new self($dbHost, $dbUser, $dbPasswd, $dbName, $dbCharset);
  }
  return self::$_instance;
 }
 
 /
   Query 查询
  
   @param String $strSql SQL语句
   @param String $queryMode 查询方式(All or Row)
   @param Boolean $debug
   @return Array
  /
 public function query($strSql, $queryMode = 'All', $debug = false)
 {
  if ($debug === true) $this->debug($strSql);
  $recordset = $this->dbh->query($strSql);
  $this->getPDOError();
  if ($recordset) {
   $recordset->setFetchMode(PDO::FETCH_ASSOC);
   if ($queryMode == 'All') {
    $result = $recordset->fetchAll();
   } elseif ($queryMode == 'Row') {
    $result = $recordset->fetch();
   }
  } else {
   $result = null;
  }
  return $result;
 }
 
 /
   Update 更新
  
   @param String $table 表名
   @param Array $arrayDataValue 字段与值
   @param String $where 条件
   @param Boolean $debug
   @return Int
  /
 public function update($table, $arrayDataValue, $where = '', $debug = false)
 {
  $this->checkFields($table, $arrayDataValue);
  if ($where) {
   $strSql = '';
   foreach ($arrayDataValue as $key => $value) {
    $strSql .= ", `$key`='$value'";
   }
   $strSql = substr($strSql, 1);
   $strSql = "UPDATE `$table` SET $strSql WHERE $where";
  } else {
   $strSql = "REPLACE INTO `$table` (`".implode('`,`', array_keys($arrayDataValue))."`) VALUES ('".implode("','", $arrayDataValue)."')";
  }
  if ($debug === true) $this->debug($strSql);
  $result = $this->dbh->exec($strSql);
  $this->getPDOError();
  return $result;
 }
 
 /
   Insert 插入
  
   @param String $table 表名
   @param Array $arrayDataValue 字段与值
   @param Boolean $debug
   @return Int
  /
 public function insert($table, $arrayDataValue, $debug = false)
 {
  $this->checkFields($table, $arrayDataValue);
  $strSql = "INSERT INTO `$table` (`".implode('`,`', array_keys($arrayDataValue))."`) VALUES ('".implode("','", $arrayDataValue)."')";
  if ($debug === true) $this->debug($strSql);
  $result = $this->dbh->exec($strSql);
  $this->getPDOError();
  return $result;
 }
 
 /
   Replace 覆盖方式插入
  
   @param String $table 表名
   @param Array $arrayDataValue 字段与值
   @param Boolean $debug
   @return Int
  /
 public function replace($table, $arrayDataValue, $debug = false)
 {
  $this->checkFields($table, $arrayDataValue);
  $strSql = "REPLACE INTO `$table`(`".implode('`,`', array_keys($arrayDataValue))."`) VALUES ('".implode("','", $arrayDataValue)."')";
  if ($debug === true) $this->debug($strSql);
  $result = $this->dbh->exec($strSql);
  $this->getPDOError();
  return $result;
 }
 
 /
   Delete 删除
  
   @param String $table 表名
   @param String $where 条件
   @param Boolean $debug
   @return Int
  /
 public function delete($table, $where = '', $debug = false)
 {
  if ($where == '') {
   $this->outputError("'WHERE' is Null");
  } else {
   $strSql = "DELETE FROM `$table` WHERE $where";
   if ($debug === true) $this->debug($strSql);
   $result = $this->dbh->exec($strSql);
   $this->getPDOError();
   return $result;
  }
 }
 
 /
   execSql 执行SQL语句
  
   @param String $strSql
   @param Boolean $debug
   @return Int
  /
 public function execSql($strSql, $debug = false)
 {
  if ($debug === true) $this->debug($strSql);
  $result = $this->dbh->exec($strSql);
  $this->getPDOError();
  return $result;
 }
 
 /
   获取字段最大值
   
   @param string $table 表名
   @param string $field_name 字段名
   @param string $where 条件
  /
 public function getMaxValue($table, $field_name, $where = '', $debug = false)
 {
  $strSql = "SELECT MAX(".$field_name.") AS MAX_VALUE FROM $table";
  if ($where != '') $strSql .= " WHERE $where";
  if ($debug === true) $this->debug($strSql);
  $arrTemp = $this->query($strSql, 'Row');
  $maxValue = $arrTemp["MAX_VALUE"];
  if ($maxValue == "" || $maxValue == null) {
   $maxValue = 0;
  }
  return $maxValue;
 }
 
 /
   获取指定列的数量
   
   @param string $table
   @param string $field_name
   @param string $where
   @param bool $debug
   @return int
  /
 public function getCount($table, $field_name, $where = '', $debug = false)
 {
  $strSql = "SELECT COUNT($field_name) AS NUM FROM $table";
  if ($where != '') $strSql .= " WHERE $where";
  if ($debug === true) $this->debug($strSql);
  $arrTemp = $this->query($strSql, 'Row');
  return $arrTemp['NUM'];
 }
 
 /
   获取表引擎
   
   @param String $dbName 库名
   @param String $tableName 表名
   @param Boolean $debug
   @return String
  /
 public function getTableEngine($dbName, $tableName)
 {
  $strSql = "SHOW TABLE STATUS FROM $dbName WHERE Name='".$tableName."'";
  $arrayTableInfo = $this->query($strSql);
  $this->getPDOError();
  return $arrayTableInfo[0]['Engine'];
 }
 
 /
   beginTransaction 事务开始
  /
 private function beginTransaction()
 {
  $this->dbh->beginTransaction();
 }
 
 /
   mit 事务提交
  /
 private function mit()
 {
  $this->dbh->mit();
 }
 
 /
   rollback 事务回滚
  /
 private function rollback()
 {
  $this->dbh->rollback();
 }
 
 /
   transaction 通过事务处理多条SQL语句
   调用前需通过getTableEngine判断表引擎是否支持事务
  
   @param array $arraySql
   @return Boolean
  /
 public function execTransaction($arraySql)
 {
  $retval = 1;
  $this->beginTransaction();
  foreach ($arraySql as $strSql) {
   if ($this->execSql($strSql) == 0) $retval = 0;
  }
  if ($retval == 0) {
   $this->rollback();
   return false;
  } else {
   $this->mit();
   return true;
  }
 }
 
 /
   checkFields 检查指定字段是否在指定数据表中存在
  
   @param String $table
   @param array $arrayField
  /
 private function checkFields($table, $arrayFields)
 {
  $fields = $this->getFields($table);
  foreach ($arrayFields as $key => $value) {
   if (!in_array($key, $fields)) {
    $this->outputError("Unknown column `$key` in field list.");
   }
  }
 }
 
 /
   getFields 获取指定数据表中的全部字段名
  
   @param String $table 表名
   @return array
  /
 private function getFields($table)
 {
  $fields = array();
  $recordset = $this->dbh->query("SHOW COLUMNS FROM $table");
  $this->getPDOError();
  $recordset->setFetchMode(PDO::FETCH_ASSOC);
  $result = $recordset->fetchAll();
  foreach ($result as $rows) {
   $fields[] = $rows['Field'];
  }
  return $fields;
 }
 
 /
   getPDOError 捕获PDO错误信息
  /
 private function getPDOError()
 {
  if ($this->dbh->errorCode() != '00000') {
   $arrayError = $this->dbh->errorInfo();
   $this->outputError($arrayError[2]);
  }
 }
 
 /
   debug
   
   @param mixed $debuginfo
  /
 private function debug($debuginfo)
 {
  var_dump($debuginfo);
  exit();
 }
 
 /
   输出错误信息
   
   @param String $strErrMsg
  /
 private function outputError($strErrMsg)
 {
  throw new Exception('MySQL Error: '.$strErrMsg);
 }
 
 /
   destruct 关闭数据库连接
  /
 public function destruct()
 {
  $this->dbh = null;
 }
}
?>

<?php
require 'MyPDO.class.php';
$db = MyPDO::getInstance('localhost', 'root', '123456', 'test', 'utf8');
 
//do something...
 
$db->destruct();
?>