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设计模式(7)-模板（从事务处理应用的模板）

首先看一个对于数据库操作的程序：

<div class="cnblogs_Highlighter"><pre class="brush:cpp;gutter:false;">#include <iostream>
 
using namespace std;
 
class DataOper{
public: 
    void insertStu(){
        cout<<"开连接..."<<endl;
        cout<<"开启事务..."<<endl;
        cout<<"执行insert()操作"<<endl;
        cout<<"提交事务..."<<endl;
        cout<<"关连接..."<<endl;
    }
 
    void updateStu(){
        cout<<"开连接..."<<endl;
        cout<<"开启事务..."<<endl;
        cout<<"执行update()操作"<<endl;
        cout<<"提交事务..."<<endl;
        cout<<"关连接..."<<endl;
    }
 
    void deleteStu(){
        cout<<"开连接..."<<endl;
        cout<<"开启事务..."<<endl;
        cout<<"执行delete()操作"<<endl;
        cout<<"提交事务..."<<endl;
        cout<<"关连接..."<<endl;
    }
};
 
void main(){
    DataOper* dataOper = new DataOper();
    dataOper->insertStu();
    dataOper->updateStu();
    dataOper->deleteStu();
}
</pre>
</div>

我们看运行结果有多个重复的操作

如何避免呢，就是使用模板把我们不需要重复操作的地方封装起来。

看一下新版代码：

#include <iostream>
 
using namespace std;
 
class DataTemplate{
private:
    void beginConnection(){
        cout<<"开连接..."<<endl;
    }
    void beginTransation(){
        cout<<"开启事务..."<<endl;
    }
    void commitTransation(){
        cout<<"提交事务..."<<endl;
    }
    void closeConnection(){
        cout<<"关连接..."<<endl;
    }
public:
     
    virtual void insertData() = 0;
    virtual void updateData() = 0;
    virtual void deleteData() = 0;
     
    void insertStu(){
        beginConnection();
        beginTransation();
        insertData();
        commitTransation();
        closeConnection();
    }
     
    void updateStu(){
        beginConnection();
        beginTransation();
        updateData();
        commitTransation();
        closeConnection();
    }
     
    void deleteStu(){
        beginConnection();
        beginTransation();
        deleteData();
        commitTransation();
        closeConnection();
    }
};
 
class DataDeal : public DataTemplate{
public:
    virtual void insertData(){
        cout<<"执行insert()操作"<<endl;
    }
    virtual void updateData(){
        cout<<"执行update()操作"<<endl;
    }
    virtual void deleteData(){
        cout<<"执行delete()操作"<<endl;
    }
};
 
void main(){
    DataDeal* dataDeal = new DataDeal();
    dataDeal->insertStu();
    dataDeal->updateStu();
    dataDeal->deleteStu();
}