工厂模式简单代码。为了给同时讲工厂模式写的范例代码。

/*****************************************
*简单工厂模式例子
* 封装一个支持多种数据库的访问层操作
* 利用简单工厂模式，达到客户端调用不关心后台数据库类型
* <liqinglin@gmail.com> 2005.7.7
*/

#include <iostream>
#include <sstream>
#include <string>

using namespace std;

class DbHelper{

public:
virtual bool createConnect() =0;
virtual bool closeConnect() =0;
};

class MsDbHelper: public DbHelper{//支持MS SQL

public:

MsDbHelper()
{
cout <<"start ms sql"<<endl;
}

bool createConnect(){
cout << "this is MS SQL" << endl;
return false;
}

bool closeConnect(){
return true;
}
};


class MysqlDbHelper: public DbHelper{//支持MYSQL

public:
MysqlDbHelper()
{
cout <<"start mysql"<<endl;
}
bool createConnect(){
cout << "this is Mysql" << endl;
return false;
}
bool closeConnect(){
return true;
}
};

class Factory{

public:
DbHelper* creator(int flag)//flag更通用的做法是从XML配置文档中来读取
{
if(flag==1)
return new MsDbHelper();
else if(flag==2)
return new MysqlDbHelper();
}
};

void testIt(DbHelper *hd)
{
hd->createConnect();
}

int main(int argc,char **argv)
{
Factory fy;
DbHelper *hd=fy.creator(2);

testIt(hd);


exit(0);
}

运行结果：

[root@stone pattern]# ./factory
start mysql
this is Mysql