c++ 连接mysql类

文章来源：http://hi.baidu.com/lbxthinker/blog/item/9b837b0f8a306fdb7acbe113.html

connpool.h文件

/**

*数据库连接池(单例模式)

*

*@authour libingxiang

*

*@email lbxthinker@gmail.com

**/

#ifndef CONN_POOL_H

#define CONN_POOL_H

#include <mysql_connection.h>

#include <mysql_driver.h>

#include <cppconn/driver.h>

#include <cppconn/exception.h>

#include <cppconn/resultset.h>

#include <cppconn/statement.h>

#include <cppconn/prepared_statement.h>

#include "push.h"

#include "mutex.h"

using namespace std;

class ConnPool{

private:

deque<sql::Connection *> conns;//连接队列

int curSize;//当前队列中路连接数目

int maxSize;//最大连接数目

sql::ConnectOptionsMap connectionProperties;

Mutex *lock;//连接队列互斥锁

static ConnPool * connPool;

sql::Driver * driver;//mysql connector C++ driver

sql::Connection * CreateConnection();//创建一个连接

void TerminateConnection(sql::Connection * conn);//终止一个连接

void Init(int initialSize);//初始化连接池

void Destroy();//销毁连接池

protected:

ConnPool(string host,string user,string password,int maxSize);

public:

~ConnPool();

sql::Connection * GetConnection();//获取一个连接

void ReleaseConnection(sql::Connection * conn);//释放一个连接

sql::Connection * GetConnectionTry(int maxNum);//GetConnection的加强版，maxNum代表重试次数

static ConnPool * GetInstance();//获取一个ConnPool对象实例

};

#endif

connpool.cpp文件

/**

*数据库连接池

*

*@authour libingxiang

*

*@email lbxthinker@gmail.com

**/

#include <stdexcept>

#include "connpool.h"

#include "config.h"

using namespace std;

extern Config *config;

ConnPool * ConnPool::connPool = NULL;

ConnPool::ConnPool(string host,string user,string password,int maxSize){

connectionProperties["hostName"] = host;

connectionProperties["userName"] = user;

connectionProperties["password"] = password;

connectionProperties["OPT_CONNECT_TIMEOUT"] = 600;

connectionProperties["OPT_RECONNECT"] = true;

this->maxSize = maxSize;

this->lock = new Mutex();

this->curSize = 0;

//初始化driver

try{

this->driver = sql::mysql::get_driver_instance(); //这里不是线程安全的

}

catch(sql::SQLException &e){

string errorMsg = string("SQLException: ") + e.what() + string(" MySQL error code: ") + int_to_string(e.getErrorCode()) + string(" SQLState ") + e.getSQLState();

Log::Write(__FILE__,__FUNCTION__,__LINE__,errorMsg);

}

catch(std::runtime_error &e){

string errorMsg = string("runtime_error: ") + e.what();

Log::Write(__FILE__,__FUNCTION__,__LINE__,errorMsg);

}

//初始化连接池

this->Init(maxSize/2);

}

ConnPool::~ConnPool(){

this->Destroy();

delete lock;

}

ConnPool *ConnPool::GetInstance(){

if(connPool == NULL) {

connPool = new ConnPool(config->GetVar("db_host"),config->GetVar("db_user"),config->GetVar("db_password"),string_to_int(config->GetVar("max_db_conn_size")));

}

return connPool;

}

void ConnPool::Init(int size){

sql::Connection * conn ;

lock->Lock();

for(int i = 0; i < size ;){

conn = this->CreateConnection();

if(conn){

i++;

conns.push_back(conn);

++curSize;

}

else{

Log::Write(__FILE__,__FUNCTION__,__LINE__,"Init connpooo fail one");

}

}

lock->UnLock();

}

void ConnPool::Destroy(){

deque<sql::Connection *>::iterator pos;

lock->Lock();

for(pos = conns.begin(); pos != conns.end();++pos){

this->TerminateConnection(*pos);

}

curSize = 0;

conns.clear();

lock->UnLock();

}

sql::Connection * ConnPool::CreateConnection(){//这里不负责curSize的增加

sql::Connection *conn;

try{

conn = driver->connect(connectionProperties);

Log::Write(__FILE__,__FUNCTION__,__LINE__,"create a mysql conn");

return conn;

}

catch(sql::SQLException &e){

string errorMsg = string("SQLException:") + e.what() + string(" MySQL error code: ") + int_to_string(e.getErrorCode()) + string(" SQLState ") + e.getSQLState();

Log::Write(__FILE__,__FUNCTION__,__LINE__,errorMsg);

return NULL;

}

catch(std::runtime_error &e){

string errorMsg = string("runtime_error: ") + e.what();

Log::Write(__FILE__,__FUNCTION__,__LINE__,errorMsg);

return NULL;

}

}

void ConnPool::TerminateConnection(sql::Connection * conn){

if(conn){

try{

conn->close();

}

catch(sql::SQLException &e){

string errorMsg = string("SQLException:") + e.what() + string(" MySQL error code: ") + int_to_string(e.getErrorCode()) + string(" SQLState ") + e.getSQLState();

Log::Write(__FILE__,__FUNCTION__,__LINE__,errorMsg);

}

catch(std::runtime_error &e){

string errorMsg = string("runtime_error: ") + e.what();

Log::Write(__FILE__,__FUNCTION__,__LINE__,errorMsg);

}

delete conn;

}

}

sql::Connection * ConnPool::GetConnection(){

sql::Connection * conn;

lock->Lock();

if(conns.size() > 0){//有空闲连接,则返回

conn = conns.front();

conns.pop_front();

if(conn->isClosed()){ //如果连接关闭,则重新打开一个连接

Log::Write(__FILE__,__FUNCTION__,__LINE__,"a mysql conn has been closed");

delete conn;

conn = this->CreateConnection();

}

if(conn == NULL){ //创建连接不成功

--curSize;

}

lock->UnLock();

return conn;

}

else{

if(curSize < maxSize){//还可以创建新的连接

conn = this->CreateConnection();

if(conn){

++curSize;

lock->UnLock();

return conn;

}

else{

lock->UnLock();

return NULL;

}

}

else{//连接池已经满了

lock->UnLock();

return NULL;

}

}

}

void ConnPool::ReleaseConnection(sql::Connection * conn){

if(conn){

lock->Lock();

conns.push_back(conn);

lock->UnLock();

}

}

sql::Connection * ConnPool::GetConnectionTry(int maxNum){

sql::Connection * conn;

for(int i = 0; i < maxNum; ++i){

conn = this->GetConnection();

if(conn){

return conn;

}

else {

sleep(2);

}

}

return NULL;

}

实现是基于mysql connector C++ api的

magicdb.h文件

/**

*mysql connector C++ 封装

*

*@authour libingxiang

*

*@email lbxthinker@gmail.com

*

**/

#ifndef MAGICDB_H

#define MAGICDB_H

#include <mysql_connection.h>

#include <mysql_driver.h>

#include <cppconn/driver.h>

#include <cppconn/exception.h>

#include <cppconn/resultset.h>

#include <cppconn/statement.h>

#include <cppconn/prepared_statement.h>

#include "push.h"

#include "connpool.h"

using namespace std;

class MagicDB {

private:

ConnPool *connPool;

public:

MagicDB();

~MagicDB();

sql::ResultSet *Query(const string &database,const string &sql);

int Execute(const string &database,const string &sql);

};

#endif

magicdb.cpp文件

/**

*mysql connector C++ 封装

*

*@authour libingxiang

*

*@email lbxthinker@gmail.com

*

**/

#include <stdexcept>

#include "magicdb.h"

#include "log.h"

#include "util.h"

using namespace std;

MagicDB::MagicDB(){

this->connPool = ConnPool::GetInstance();

}

sql::ResultSet * MagicDB::Query(const string &database,const string &sql){

sql::Connection *conn;

sql::Statement *stmt;

sql::ResultSet *res;

try{

conn = connPool->GetConnection(); //从连接池中获取连接

if(conn == NULL){

conn = connPool->GetConnectionTry(2);

if(conn == NULL){

Log::Write(__FILE__,__FUNCTION__,__LINE__,"query get conn error");

return NULL;

}

}

conn->setSchema(database);

stmt = conn->createStatement();

res = stmt->executeQuery(sql.c_str());

connPool->ReleaseConnection(conn);//将连接放入连接池中

delete stmt;

return res;

}

catch(sql::SQLException &e){

string errorMsg = string("SQLException:") + e.what() + string(" MySQL error code: ") + int_to_string(e.getErrorCode()) + string(" SQLState ") + e.getSQLState();

Log::Write(__FILE__,__FUNCTION__,__LINE__,errorMsg);

connPool->ReleaseConnection(conn);//将连接放入连接池中

delete stmt;

delete res;

return NULL;

}

catch(std::runtime_error &e){

string errorMsg = string("runtime_error: ") + e.what();

Log::Write(__FILE__,__FUNCTION__,__LINE__,errorMsg);

connPool->ReleaseConnection(conn);//将连接放入连接池中

delete stmt;

delete res;

return NULL;

}

}

int MagicDB::Execute(const string &database,const string &sql){

sql::Statement * stmt;

sql::Connection *conn;

try{

conn = connPool->GetConnection(); //从连接池中获取连接

if(conn == NULL){

conn = connPool->GetConnectionTry(2);

if(conn == NULL){

Log::Write(__FILE__,__FUNCTION__,__LINE__,"query get conn error");

return -3;

}

}

conn->setSchema(database);

stmt = conn->createStatement();

stmt->execute(sql.c_str());

connPool->ReleaseConnection(conn);//将连接放入连接池中

delete stmt;

return 0;

}

catch(sql::SQLException &e){

string errorMsg = string("SQLException:") + e.what() + string(" MySQL error code: ") + int_to_string(e.getErrorCode()) + string(" SQLState ") + e.getSQLState();

Log::Write(__FILE__,__FUNCTION__,__LINE__,errorMsg);

connPool->ReleaseConnection(conn);//将连接放入连接池中

delete stmt;

return -1;

}

catch(std::runtime_error &e){

string errorMsg = string("runtime_error: ") + e.what();

Log::Write(__FILE__,__FUNCTION__,__LINE__,errorMsg);

connPool->ReleaseConnection(conn);//将连接放入连接池中

delete stmt;

return -2;

}

}

MagicDB::~MagicDB(){

delete connPool;

}