抽象工厂

抽象工厂

提供一个接口，让该接口负责创建一系列“相关或者相互依赖的对象”，无需指定它们具体的类。

class DBConnection
{
public:
  DBConnection(){ }
  virtual ~DBConnection(){ }
  virtual bool connectionString() = 0;
}

class DBCommand
{
public:
  DBCommand(){ }
  virtual ~DBCommand(){ }
  virtual void setConnection() = 0;
  virtual bool commandText() = 0;
  virtual DBDataReader* executeReader() = 0;
}

class DBDataReader
{
public:
  DBDataReader(){ }
  virtual ~DBDataReader(){ }
  virtual bool read() = 0;
}

class DBFactory
{
public:
  DBFactory(){ }
  virtual ~DBFactory(){ }
  virtual DBConnection* createDBConnection() = 0;
  virtual DBCommand* createDBCommand() = 0;
  virtual DBDataReader* createDBDataReader() = 0;
}

class Employees
{
public:
  void getEmployees()
  {
    DBConnection* connection=factory_->createDBConnection();
    connection->connectionString();
    
    DBCommand* command=factory_->createDBCommand();
    command->setConnection();//相关联
    command->commandText();
    
    DBDataReader* reader=command->executeReader();//相关联
    while(reader->read())
    {
      
    }
	}
  
private:
  DBFactory* factory_;
}

class MysqlDBConnection : 
{
public:
 	virtual bool connectionString() overrive
  {
    //...
  }
}

class DBCommand
{
public:
  virtual void setConnection()
  {
    //...
  }
  
  virtual bool commandText()
  {
    //...
  }
  
  virtual DBDataReader* executeReader()
  {
    //...
  }
}

class DBDataReader
{
public:
  virtual bool read()
  {
    //...
  }
}

class DBFactory
{
public:
  virtual DBConnection* createDBConnection()
  {
    //...
	}
  virtual DBCommand* createDBCommand()
  {
    //...
  }
  virtual DBDataReader* createDBDataReader()
  {
    //...
  }
}

UML类图