[置顶] 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   275076730@qq.coom
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   275076730@qq.coom
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：