太原模板建站系统,ck网站,广东seo网站设计价格,中国建筑招标投标网官网1、预处理相关API
mysql_stmt_init#xff1a;初始化生成一个预编译处理的Stmt对象mysql_stmt_prepare#xff1a;预处理SQL语句#xff0c;值部分用#xff1f;进行占位#xff08;可以防止SQL注入#xff09;mysql_stmt_bind_param#xff1a;给预处理的SQL语句中的初始化生成一个预编译处理的Stmt对象mysql_stmt_prepare预处理SQL语句值部分用进行占位可以防止SQL注入mysql_stmt_bind_param给预处理的SQL语句中的进行值绑定 MYSQL_BIND MYSQL_TYPE_XXX数据类型int、long、string、blob…buffer数据值的指针buffer_length数据长度如果是整形数据可以不传入 mysql_stmt_execute执行SQL语句mysql_stmt_close关闭Stmt对象
MYSQL_STMT * STDCALL mysql_stmt_init(MYSQL *mysql);
int STDCALL mysql_stmt_prepare(MYSQL_STMT *stmt, const char *query, unsigned long length);
my_bool STDCALL mysql_stmt_bind_param(MYSQL_STMT * stmt, MYSQL_BIND * bnd);
int STDCALL mysql_stmt_execute(MYSQL_STMT *stmt);
my_bool STDCALL mysql_stmt_close(MYSQL_STMT * stmt);2、通过预编译接口插入图片到数据库
将一张图片存到数据库中然后再从数据库中读取出来
2.1、建立连接
MYSQL mysql;// 初始化mysql结构体并且初始化服务连接环境mysql_init(mysql);const char *host 127.0.0.1;const char *user root;const char *password 123456;const char *db cpp;int timeout 3;// 连接超时时长设置mysql_options(mysql, MYSQL_OPT_CONNECT_TIMEOUT, timeout);// 断开重连设置int reconnect 1;mysql_options(mysql, MYSQL_OPT_RECONNECT, reconnect);// MySQL连接建立if(!mysql_real_connect(mysql, host, user, password, db, 3306, 0, CLIENT_MULTI_STATEMENTS)){std::cout mysql connect failed! mysql_error(mysql) std::endl;}else{std::cout mysql connect host success! std::endl;}// .....mysql_close(mysql);mysql_library_end();2.2、创建表
MySQL中存取文件可以用blob来表示表示使用二进制的方式存储
void create_table(MYSQL mysql)
{string sql CREATE TABLE IF NOT EXISTS t_data (\id int(10) unsigned AUTO_INCREMENT,\name varchar(1024),\data blob,\size int,\PRIMARY KEY (id)\) ENGINEInnoDB DEFAULT CHARSETutf8;;if(mysql_real_query(mysql, sql.c_str(), sql.length()) ! 0){cout mysql_query failed! endl;}
}2.3、存入图片到MySQL中
这里主要通过ftsream来计算文件的大小也可以通过其他手段例如stat.h、lseek函数Linux环境
void insert_picture(MYSQL mysql)
{// 1. 初始化stmt预处理对象MYSQL_STMT *stmt mysql_stmt_init(mysql);string sql insert into t_data(name, data, size) values(?,?,?);;if(mysql_stmt_prepare(stmt, sql.c_str(), sql.length()) ! 0){cerr mysql_stmt_prepare failed! mysql_stmt_error(stmt) endl;}// 2. 绑定数据string filename touxiang.jpg;fstream in(filename, ios::in | ios::binary);if (!in.is_open()){cerr open file error! endl;}in.seekg(0, ios::end);int filesize in.tellg();in.seekg(0, ios::beg);char *data new char[filesize];int readed 0, current_filesize filesize;while(!in.eof()){in.read(datareaded, current_filesize-readed);if(in.gcount() 0) break;readed in.gcount();}in.close();MYSQL_BIND bind[3] {0};bind[0].buffer_type MYSQL_TYPE_STRING;bind[0].buffer (char *)filename.c_str();bind[0].buffer_length filename.length();bind[1].buffer_type MYSQL_TYPE_BLOB;bind[1].buffer data;bind[1].buffer_length filesize;bind[2].buffer_type MYSQL_TYPE_LONG;bind[2].buffer filesize;// 3. 将占位符的参数替换成实际数据if(mysql_stmt_bind_param(stmt, bind) ! 0) {cerr mysql_stmt_bind_param error! endl;}// 4. 执行实际的mysql语句if(mysql_stmt_execute(stmt) ! 0){cerr mysql_stmt_execute error! mysql_stmt_error(stmt) endl;}else{cout mysql_stmt_execute success! affect row mysql_stmt_affected_rows(stmt) , insert data id mysql_stmt_insert_id(stmt) endl;}// 5. 关闭连接if(mysql_stmt_close(stmt) ! 0){cerr mysql_stmt_close error! endl;}// 释放所有资源delete []data;
}2.4、将数据库中的图片取出来
void select_data(MYSQL mysql)
{string sql select *from t_data limit 0, 1;if (mysql_real_query(mysql, sql.c_str(), sql.length()) ! 0){cerr mysql_real_query error mysql_error(mysql) endl;}MYSQL_RES *result mysql_store_result(mysql);MYSQL_ROW row mysql_fetch_row(result);if(!row){cerr mysql_fetch_row error mysql_error(mysql) endl;}unsigned long* lens mysql_fetch_lengths(result);MYSQL_FIELD *mysqlField mysql_fetch_fields(result);int field_count mysql_num_fields(result);for(int i 0;i field_count;i){cout mysqlField[i].name , length lens[i] endl;}string filename(out_);filename row[1];fstream out(filename, ios::out | ios::binary);if(!out.is_open()){cerr open file failed! endl;}out.write(row[2], lens[2]);out.flush();out.close();
}
