修改后的MYSQL数据访问层-db类

/**
* 数据访问层，仅处理MYSQL
* 包括
* by:李勇
* at:2009-01-19
*/

include_once(rootpath."inc/table.class.php");       //数据表访问类
include_once(rootpath."inc/exception.class.php");   //异常类

final class DalDb{
    private $config;    //取数据库配置信息，因为数据库已经分布存放
    private $tables;    //本数据库中所有表
    private $dbName;    //数据库名称
    private $pdo;       //数据库连接参数

    /**
     * 构造方法
     *
     * @param string $dbName
     */
    public function __construct($dbName){
        if(!is_string($dbName)){
            throw new DalException(DalException::DE_DB_CONSTRUCTOR_WRONG ,array($dbName));
        }
        if(!$dbName){
            throw new DalException(DalException::DE_DB_CONSTRUCTOR_NULL );
        }
        $this->dbName=$dbName;
        $this->pdo=false;
        $this->config=false;
        $this->tables=array();
    }

    /**
     * 读取配置信息
     *
     */
    private function config(){
        $file=BSPath.DIRECTORY_SEPARATOR."configs".DIRECTORY_SEPARATOR."VDBMSCONFIG.conf";
        if(!file_exists($file)){
            throw new DalException(DalException::DE_DB_CONFIG_FILE ,array($file));
        }
        $configString=file_get_contents($file);
        if($configString===false){
            throw new DalException(DalException::DE_DB_CONFIG_READ ,array($file));
        }
        if(!$configString){
            throw new DalException(DalException::DE_DB_CONFIG_NULL ,array($file));
        }
        $json=json_decode($configString);
        if(!is_object($json)){
            throw new DalException(DalException::DE_DB_CONFIG_JSON ,array($configString));
        }
        $config=get_object_vars($json);
        if(!$config){
            throw new DalException(DalException::DE_DB_CONFIG_OBJ_NULL ,array($json));
        }
        if(!isset($config[$this->dbName])){
            throw new DalException(DalException::DE_DB_CONFIG_DB ,array($this->dbName));
        }
        if(!isset($config[$this->dbName]->splitdb)){
            throw new DalException(DalException::DE_DB_CONFIG_SPLIT ,array($this->dbName,$config));
        }
        if(!isset($config[$this->dbName]->splitdb[0])){
            throw new DalException(DalException::DE_DB_CONFIG_SPLIT_NULL ,array($config,$this->dbName));
        }
        $this->config=get_object_vars($config[$this->dbName]->splitdb[0]);
    }

    /**
     * 连接数据库
     *
     * @return handler PDO连接
     */
    private function connect(){
        if($this->pdo!==false)return $this->pdo;
        if(!$this->config) $this->config();

        $dsn='mysql:dbname='.$this->dbName.';host='.$this->config['ip'].';port='.$this->config['port'];
        try {
            $pdo=new PDO($dsn,$this->config['user'],$this->config['pass']);
        }catch (PDOException $e){
            throw new DalException(DalException::DE_DB_CONNECT_FAILURE ,array($dsn,$this->config['user'],$this->config['pass']));
        }

        $this->pdo=$pdo;

        $pdo->exec("SET NAMES  ".YIQI_DB_CHARSET);
        $statement=$pdo->query('show tables');
        $result=$statement->fetchAll();

        $this->tables=array();
        foreach($result as $row){
            $tableName=$row[0];
            $this->tables[$tableName]=false;
        }
        return $this->pdo;
    }

    /**
     * 生成数据表访问对象
     *
     * @param string $table 表名
     * @return object 数据表访问对象
     */
    private function table($table){
        if(isset($this->tables[$table]) and $this->tables[$table]) return $this->tables[$table];

        $this->connect();

        if(!isset($this->tables[$table])){
            throw new DalException(DalException::DE_DB_TABLE ,array($this->dbName,$table));
        }

        $obj=new DalTable($this->pdo,$table);
        $this->tables[$table]=$obj;
        return $obj;
    }

    /**
     * 查询数据
     *
     * @param string $table
            请参考table类同名方法
     */
    public function select($table,$fields = null,$where = null,$groupby = null,$having = null,$orderby = null,$limit = null){
        $table=$this->table($table);
        return $table->select($fields,$where,$groupby,$having,$orderby,$limit);
    }

    /**
     * 查询消重后的数据
     *
     * @param string $table
            请参考table类同名方法
     */
    public function distinct($table,$fields = null,$where = null,$groupby = null,$having = null,$orderby = null,$limit = null){
        $table=$this->table($table);
        return $table->distinct($fields,$where,$groupby,$having,$orderby,$limit);
    }

    /**
     * 插入数据
     *
     * @param string $table
            请参考table类同名方法
     */
    public function insert($table,$row){
        $table=$this->table($table);
        return $table->insert($row);
    }

    /**
     * 删除数据
     *
     * @param string $table
            请参考table类同名方法
     */
    public function delete($table,$where){
        $table=$this->table($table);
        return $table->detele($where);
    }

    /**
     * 删除表中所有数据
     *
     * @param string $table
            请参考table类同名方法
     */
    public function deleteAll($table){
        $table=$this->table($table);
        return $table->deleteAll();
    }

    /**
     * 计数
     *
     * @param string $table
            请参考table类同名方法
     */
    public function count($table,$where=null){
        $table=$this->table($table);
        return $table->count($where);
    }

    /**
     * 修改数据行
     *
     * @param string $table
            请参考table类同名方法
     */
    public function update($table,$row,$where){
        $table=$this->table($table);
        return $table->update($row,$where);
    }

    /**
     * 执行SQL语句
     *
     * @param string $sql
     * @return int      影响的行数
     */
    public function execute($sql){
        $this->connect();
        if(!is_string($sql)){
            throw new DalException(DalException::DE_DB_EXECUTE ,array($sql));
        }
        return $this->pdo->exec(trim($sql));
    }

    /**
     * 执行查询语句
     *
     * @param string $sql
     * @return mixed
     */
    public function query($sql){
        $this->connect();
        if(!is_string($sql)){
            throw new DalException(DalException::DE_DB_QUERY ,array($sql));
        }
        return $this->pdo->query(trim($sql));
    }

}