数据库连接池c++ （msyql） mysql connector c++ 的使用

Mysql Connector/C++ 使用介绍

一、下载mysql connector c++和 boost库

wget https://dev.mysql.com/get/Downloads/Connector-C++/mysql-connector-c++-1.1.8-linux-glibc2.5-x86-64bit.tar.gz

下载：根据自己的系统下载mysql connector c++版本，我们直接下载已经编译好压缩包，直接使用包里面的inlcude文件以及a文件或者so文件就可以了。当然你也可以下source源码文件自己编译安装。我是用官网的编译好的包，如下面所示。

解压出来目录如下：（只要把include和lib目录包含到自己的项目目录就可以了）

如果自己想从source源码编译出来：请按照下图页面下载就可以：

二、下载boost库编译安装boost库，因为mysql connector c++需要boost库的支持：（当然你可以直接使用yum安装）

wget https://sourceforge.net/projects/boost/files/boost/1.61.0/boost_1_61_0.tar.gz

然后解压安装，根据自己的实际情况选择安装路劲。我是默认安装的，安装步骤如下：

./bootstrap.sh

./b2

./b2 isntall

三．下面提供一个本人编写连接池，根据网上一些资料修改的。

/*
    time: 2017.3.31
    author: chenxun   [email protected]
    notice: MySql Connector C++
*/

#ifndef _DB_POOL_H_
#define _BD_POOL_H_

#include <iostream>
#include <mysql_connection.h>  
#include <mysql_driver.h>  
#include <cppconn/exception.h>  
#include <cppconn/driver.h>  
#include <cppconn/connection.h>  
#include <cppconn/resultset.h>  
#include <cppconn/prepared_statement.h>  
#include <cppconn/statement.h>  
#include <pthread.h>  
#include <list>  

using namespace std;  
using namespace sql; 

class DBPool
{
public:
    // Singleton 
    static DBPool& GetInstance();

    //init pool
    void initPool(std::string url_, std::string user_, std::string password_, int maxSize_);

    //get a conn from pool
    Connection* GetConnection();

    //put the conn back to pool
    void ReleaseConnection(Connection *conn);

    ~DBPool();

private:
    DBPool(){}

    //init DB pool
    void InitConnection(int initSize);
    
    // create a connection
    Connection* CreateConnection(); 

    //destory connection
    void DestoryConnection(Connection *conn);

    //destory db pool
    void DestoryConnPool();

private:
    string user;
    string password;
    string url;
    int maxSize;
    int curSize;

    Driver*             driver;     //sql driver (the sql will free it)
    list<Connection*>   connList;   //create conn list

    //thread lock mutex
    static pthread_mutex_t lock;     
};

#endif

cpp文件

/*
    time: 2017.3.31
    author: chenxun   [email protected]
    notice: MySql Connector C++
*/
#include <iostream>
#include <stdexcept>  
#include <exception>  
#include <stdio.h>  
#include "DBPool.h"

using namespace std;
using namespace sql;

pthread_mutex_t DBPool::lock = PTHREAD_MUTEX_INITIALIZER;

//Singleton: get the single object
DBPool& DBPool::GetInstance()
{  
    static DBPool instance_;
    return instance_;  
}

void DBPool::initPool(std::string url_, std::string user_, std::string password_, int maxSize_)
{  
    this->user = user_;  
    this->password = password_;
    this->url = url_;
    this->maxSize = maxSize_;  
    this->curSize = 0; 

    try{  
        this->driver=sql::mysql::get_driver_instance();  
    }  
    catch(sql::SQLException& e)  
    {  
        perror("Get sql driver failed");  
    }  
    catch(std::runtime_error& e)  
    {  
        perror("Run error");  
    }  
    this->InitConnection(maxSize/2);
} 

//init conn pool
void DBPool::InitConnection(int initSize)
{
    Connection* conn;  
    pthread_mutex_lock(&lock);  
    for(int i =0;i <initSize; i++)  
    {  
        conn= this->CreateConnection();  
        
        if(conn)
        {  
            connList.push_back(conn);  
            ++(this->curSize);  
        }  
        else  
        {  
            perror("create conn error");  
        }  
    }  
    pthread_mutex_unlock(&lock);  

}

Connection* DBPool::CreateConnection()
{
    Connection* conn;  
    try{  
        conn = driver->connect(this->url,this->user,this->password);  //create a conn 
        return conn;  
    }  
    catch(sql::SQLException& e)  
    {  
        perror("link error");  
        return NULL;  
    }  
    catch(std::runtime_error& e)  
    {  
        perror("run error");  
        return NULL;  
    }  
}

Connection* DBPool::GetConnection()
{  
    Connection* conn;  

    pthread_mutex_lock(&lock);

    if(connList.size()>0)//the pool have a conn 
    {  
        conn = connList.front(); 
        connList.pop_front();//move the first conn 
        if(conn->isClosed())//if the conn is closed, delete it and recreate it
        {  
            delete conn;  
            conn = this->CreateConnection();  
        }  

        if(conn == NULL)  
        {  
            --curSize;  
        }

        pthread_mutex_unlock(&lock);

        return conn;  
    }  
    else
    {  
        if(curSize< maxSize)//the pool no conn
        {
            conn = this->CreateConnection();  
            if(conn)
            {  
                ++curSize;  
                pthread_mutex_unlock(&lock);  
                return conn;  
            }  
            else
            {  
                pthread_mutex_unlock(&lock);  
                return NULL;  
            }  
        }  
        else //the conn count > maxSize
        { 
            pthread_mutex_unlock(&lock);  
            return NULL;  
        }  
    }  
}  

//put conn back to pool
void DBPool::ReleaseConnection(Connection *conn)
{
    if(conn)
    {  
        pthread_mutex_lock(&lock);  
        connList.push_back(conn);  
        pthread_mutex_unlock(&lock);  
    }  
}

void DBPool::DestoryConnPool()
{  
    list<Connection*>::iterator iter;  
    pthread_mutex_lock(&lock);  
    for(iter = connList.begin(); iter!=connList.end(); ++iter)  
    {  
        this->DestoryConnection(*iter); 
    }  
    curSize=0;  
    connList.clear();
    pthread_mutex_unlock(&lock);  
}  

 
void DBPool::DestoryConnection(Connection* conn)  
{  
    if(conn)  
    {  
        try{  
            conn->close();  
        }  
        catch(sql::SQLException&e)  
        {  
            perror(e.what());  
        }  
        catch(std::exception& e)  
        {  
            perror(e.what());  
        } 
        delete conn;  
    }  
} 
 
DBPool::~DBPool()  
{  
    this->DestoryConnPool();  
}

main.cpp文件

/*
 * main.cpp
 *
 *  Created on: 2013-3-26
 *      Author: chenxun
 */
 
#include "DBPool.h"
#include <stdio.h> 

/*--------------------------------------------------------------
    单例模式，全局唯一 db pool，程序中使用onnpool中获取一个
    db连接使用，使用完之后调用ReleaseConnection把conn放回pool中去.
----------------------------------------------------------------*/
DBPool  connpool = DBPool::GetInstance();

int main(int argc, char* argv[]) 
{
    //初始化连接，创建参数中maxSize一半的连接
    connpool.initPool("tcp://127.0.0.1:3306", "root", "123456", 100);

    Connection *con;
    Statement *state;
    ResultSet *result;
    con = connpool.GetConnection();//get a db conn
    for(int i = 0; i<1000; i++)
    {
        state = con->createStatement();
        state->execute("use mysql");
 
        // 查询
        result = state->executeQuery("select host,user from user");
 
        // 输出查询
        while (result->next()) 
        {
            try{
                string user = result->getString("user"); 
                string name = result->getString("host");
                cout << user << " : " << name << endl;
            }catch(sql::SQLException& e){
                std::cout << e.what() << std::endl;
            }
        }

        /*result = state->executeQuery("select cust_id,cust_name from customers");
        while (result->next()) 
        {
            try{
                string user = result->getString("cust_id");
                string name = result->getString("cust_name");
                cout << user << " : " << name << endl;
            }catch(sql::SQLException& e){
              std::cout << e.what() << std::endl;
            }
        }
    */
        std::cout << i << std::endl;
    
    }

    delete result;
    delete state;
    connpool.ReleaseConnection(con);

    return 0;
}

自己根据项目写一个makefile，我这里就不提供了。运行情况如下

注意include文件和so文件路劲编译选项加上-lmysqlcppconn例如：

g++ main.cpp -o main -I... -L... –lmysqlcppconn

-I接你的mysqlconnector c++文头

-L接你的msyqlconnector c++ lib路劲

运行情况如下：

数据库连接池c++ （msyql） mysql connector c++ 的使用

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