C#数据库连接池

淡淡的烟草味﹌ 2022-12-03 05:11 108阅读 0赞

## C\#数据库连接池 ##

using MySql.Data.MySqlClient;
    using System;
    using System.Collections;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    
    namespace Test
    {
        public class ConnectionPool
        {
            private static ConnectionPool cpool = null;//池管理对象
            private static Object objlock = typeof(ConnectionPool);//池管理对象实例
            private int size = 1;//池中连接数
            private int useCount = 0;//已经使用的连接数
            private ArrayList pool = null;//连接保存的集合
            private String ConnectionStr = "";//连接字符串
    
            public ConnectionPool()
            {
                //数据库连接字符串
                ConnectionStr = System.Configuration.ConfigurationManager.AppSettings["MySqlConnectionString"];
                //创建可用连接的集合
                pool = new ArrayList();
            }
    
            #region 创建获取连接池对象
            public static ConnectionPool getPool()
            {
                lock (objlock)
                {
                    if (cpool == null)
                    {
                        cpool = new ConnectionPool();
                    }
                    return cpool;
                }
            }
            #endregion
    
            #region 获取池中的连接
            public MySqlConnection getConnection()
            {
                lock (pool)
                {
                    MySqlConnection tmp = null;
                    //可用连接数量大于0
                    if (pool.Count > 0)
                    {
                        //取第一个可用连接
                        tmp = (MySqlConnection)pool[0];
                        //在可用连接中移除此链接
                        pool.RemoveAt(0);
                        //不成功
                        if (!isUserful(tmp))
                        {
                            //可用的连接数据已去掉一个
                            useCount--;
                            tmp = getConnection();
                        }
                    }
                    else
                    {
                        //可使用的连接小于连接数量
                        if (useCount <= size)
                        {
                            try
                            {
                                //创建连接
                                tmp = CreateConnection(tmp);
                            }
                            catch (Exception e)
                            {
                            }
                        }
                    }
                    //连接为null
                    if (tmp == null)
                    {
                        //达到最大连接数递归调用获取连接否则创建新连接
                        if (useCount <= size)
                        {
                            tmp = getConnection();
                        }
                        else
                        {
                            tmp = CreateConnection(tmp);
                        }
                    }
                    return tmp;
                }
            }
            #endregion
    
            #region 创建连接
            private MySqlConnection CreateConnection(MySqlConnection tmp)
            {
                //创建连接
                MySqlConnection conn = new MySqlConnection(ConnectionStr);
                conn.Open();
                //可用的连接数加上一个
                useCount++;
                tmp = conn;
                return tmp;
            }
            #endregion
    
            #region 关闭连接,加连接回到池中
            public void closeConnection(MySqlConnection con)
            {
                lock (pool)
                {
                    if (con != null)
                    {
                        //将连接添加在连接池中
                        pool.Add(con);
                    }
                }
            }
            #endregion
    
            #region 目的保证所创连接成功,测试池中连接
            private bool isUserful(MySqlConnection con)
            {
                //主要用于不同用户
                bool result = true;
                if (con != null)
                {
                    string sql = "select 1";//随便执行对数据库操作
                    MySqlCommand cmd = new MySqlCommand(sql, con);
                    try
                    {
                        cmd.ExecuteScalar().ToString();
                    }
                    catch
                    {
                        result = false;
                    }
    
                }
                return result;
            }
            #endregion
        }
    }

使用方法：  
MySqlConnection database\_con = ConnectionPool.getPool().getConnection();  
//将连接添加回连接池中  
ConnectionPool.getPool().closeConnection(database\_con);