使用单例模式设计PDO数据操作类

<?php
/**
 * MyPDO
 * @author LHL <506698615@qq.com>
 * @date 2016.04.20
 */
class MyPDO{
    protected static $_instance = null;
    protected $dbName = '';
    protected $dsn;
    protected $dbh;

    /**
     * 构造函数
     */
    private function __construct($dbhost,$dbname,$dbUser,$dbPasswd,$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($dbhost,$dbname,$dbUser,$dbPasswd,$dbCharset){
        if(self::$_instance == null){
            self::$_instance = new self($dbhost,$dbname,$dbUser,$dbPasswd,$dbCharset);
        }
        return self::$_instance;
    }
    /*
     * Query 查询
     * @param String $strSql      SQL查询语句
     * @param String $queryModel  查询方式(All or Row)
     * @param Boolen $debug
     * return Array
     */
    public function query($strSql,$queryModel='All',$debug=false){
        if($debug === true) $this->debug($strSql);
        $recordset = $this->dbh->query($strSql);
        $this->getPDOError();
        if($recordset){
            $recordset->setFetchMode(PDO::FETCH_ASSOC);
            if($queryModel == 'All'){
                $result = $recordset->fetchAll();
            }elseif($queryModel == '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 = true)
    {
        $this->checkFields($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();
    }

    /**
     * commit 事务提交
     */
    private function commit()
    {
        $this->dbh->commit();
    }

    /**
     * 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->commit();
            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);
    }
    /**
     * 抛出错误信息
     * @param string $strErrMsg
     */
    private function outputError($strErrMsg){
        throw new Exception('MySQL Error:'.$strErrMsg);
    }
    /**
     * 关闭数据库连接
     */
    public function destruct(){
        $this->dbh = null;
    }
}
$db = MyPDO::getInstance('localhost','test','root','','utf8');
$sql = "select * from article";
$result = $db->query($sql);
echo '<pre>';
print_r($result);
echo '</pre>';
?>