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上一講中基本實現了對數據庫的讀寫分離，而在選擇只讀數據庫上只是隨機選擇，并沒有去檢測數據庫服務器是否有效，如服務器掛了，ＳＱＬ服務停了，端口被封了等等，而本講主要對以上功能進行一個實現，并對配置文件也進行了一些優化，讓它更好的支持多個數據庫服務器，分別配置各個的賬號和密碼及數據庫服務端口等等，接下來，就來看一下主要的代碼吧。
一 配置文件
<!-- ef實現對sql讀寫分離的配置，sqlserver端采用發布與訂閱實現 -->
<add key="readDb" value="
192.168.2.71|1433|background_read1|sa|zzl123,
192.168.2.71|1433|TestWrite_Read_Zzl|sa|zzl123,
192.168.2.29|1433|TestWrite_Read_Zzl|sa|1"
/>
<!-- 只讀服務器的sql連接串配置模版-->
<add key ="readDbConnectioin" value="data source={0};initial catalog={1};persist security info=True;user id={2};password={3};multipleactiveresultsets=True;application name=EntityFramework"/>
二 數據庫配置實體類
/// <summary> /// 只讀數據庫配置實體 /// </summary> public class ReadDbConfig { public ReadDbConfig() { Port = 1433; UserId = "sa"; } public string Ip { get; set; } public int Port { get; set; } public string DbName { get; set; } public string UserId { get; set; } public string Password { get; set; } }
三 對ＳＱＬ攔截器進行優化，添加了TCP的心跳檢測
lock (lockObj) { if (readConnList != null && readConnList.Any()) { foreach (var item in readConnList) { //心跳測試，將死掉的服務器IP從列表中移除 var client = new TcpClient(); try { client.Connect(new IPEndPoint(IPAddress.Parse(item.Ip), item.Port)); } catch (SocketException) { //異常，沒有連接上 readConnList.Remove(item); } if (!client.Connected) { readConnList.Remove(item); } } } }
四 對于數據庫庫端還是這前通過發布和訂閱實現的，需要注意的是，這些功能需要使用“機器名”進行鏈接，使用ip和域名都是無效的
五 下面貢獻一下完成的攔截器代碼
/// <summary> /// SQL命令攔截器 /// 主要實現EF的讀寫分離 /// </summary> public class SqlCommandInterceptor : DbCommandInterceptor { static SqlCommandInterceptor() { InitConfig(); initSysTimer.Enabled = true; initSysTimer.Elapsed += initSysTimer_Elapsed; initSysTimer.Start(); sysTimer.Enabled = true; sysTimer.Elapsed += sysTimer_Elapsed; sysTimer.Start(); } private static object lockObj = new object(); /// <summary> /// 定期找沒有在線的數據庫服務器 /// </summary> private static Timer sysTimer = new Timer(6); /// <summary> /// 系統配置文件輪訓讀時間間隔 /// </summary> private static Timer initSysTimer = new Timer(60000 * 10); /// <summary> /// 讀庫，從庫集群，寫庫不用設置走默認的EF框架 /// </summary> private static List<ReadDbConfig> readConnList; /// <summary> /// 配置初始化 /// </summary> private static void InitConfig() { lock (lockObj) { var temp = new List<ReadDbConfig>(); var str = System.Configuration.ConfigurationManager.AppSettings["readDb"] ?? string.Empty; var readList = str.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries); if (readList != null && readList.Any()) { foreach (var item in readList) { var configArr = item.Split(new char[] { '|' }, StringSplitOptions.RemoveEmptyEntries); temp.Add(new ReadDbConfig { Ip = configArr[0], Port = int.Parse(configArr[1]), DbName = configArr[2], UserId = configArr[3], Password = configArr[4], }); } } readConnList = temp; } } #region Private Methods private static void initSysTimer_Elapsed(object sender, ElapsedEventArgs e) { InitConfig(); } /// <summary> /// 輪詢服務 /// </summary> /// <param name="sender"></param> /// <param name="e"></param> private static void sysTimer_Elapsed(object sender, ElapsedEventArgs e) { lock (lockObj) { if (readConnList != null && readConnList.Any()) { foreach (var item in readConnList) { //心跳測試，將死掉的服務器IP從列表中移除 var client = new TcpClient(); try { client.Connect(new IPEndPoint(IPAddress.Parse(item.Ip), item.Port)); } catch (SocketException) { //異常，沒有連接上 readConnList.Remove(item); } if (!client.Connected) { readConnList.Remove(item); } } } } } /// <summary> /// 處理讀庫字符串 /// </summary> /// <returns></returns> private string GetReadConn() { if (readConnList != null && readConnList.Any()) { var resultConn = readConnList[Convert.ToInt32(Math.Floor((double)new Random().Next(0, readConnList.Count)))]; return string.Format(System.Configuration.ConfigurationManager.AppSettings["readDbConnectioin"] , resultConn.Ip , resultConn.DbName , resultConn.UserId , resultConn.Password); } return string.Empty; } /// <summary> /// 只讀庫的選擇,加工command對象 /// </summary> /// <param name="command"></param> private void ReadDbSelect(DbCommand command) { if (!string.IsNullOrWhiteSpace(GetReadConn()))//如果配置了讀寫分離，就去實現 { if (!command.CommandText.StartsWith("insert", StringComparison.InvariantCultureIgnoreCase)) { command.Connection.Close(); command.Connection.ConnectionString = GetReadConn(); command.Connection.Open(); } } } #endregion #region Override Methods /// <summary> /// Linq to Entity生成的update,delete /// </summary> /// <param name="command"></param> /// <param name="interceptionContext"></param> public override void NonQueryExecuting(DbCommand command, DbCommandInterceptionContext<int> interceptionContext) { base.NonQueryExecuting(command, interceptionContext);//update,delete等寫操作直接走主庫 } /// <summary> /// 執行sql語句，并返回第一行第一列，沒有找到返回null,如果數據庫中值為null，則返回 DBNull.Value /// </summary> /// <param name="command"></param> /// <param name="interceptionContext"></param> public override void ScalarExecuting(DbCommand command, DbCommandInterceptionContext<object> interceptionContext) { ReadDbSelect(command); base.ScalarExecuting(command, interceptionContext); } /// <summary> /// Linq to Entity生成的select,insert /// 發送到sqlserver之前觸發 /// warning:在select語句中DbCommand.Transaction為null，而ef會為每個insert添加一個DbCommand.Transaction進行包裹 /// </summary> /// <param name="command"></param> /// <param name="interceptionContext"></param> public override void ReaderExecuting(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext) { ReadDbSelect(command); base.ReaderExecuted(command, interceptionContext); } /// <summary> /// 發送到sqlserver之后觸發 /// </summary> /// <param name="command"></param> /// <param name="interceptionContext"></param> public override void ReaderExecuted(DbCommand command, DbCommandInterceptionContext<DbDataReader> interceptionContext) { base.ReaderExecuted(command, interceptionContext); } #endregion }
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