主线程和子线程可以用同一个数据库连接

一．利用全局变量．　大家都可以访问，所以使用很方便．

二．利用PostThreadMesagge(ThreadId,Msg,0,0)来进行通讯．

其中要注意的问题是，因为利用CreateThread创建的线程是无消息获取通道，消息映射这些功能，只有有窗体的线程才具备这些功能，所以要自己获取消息队列，利用PeekMessage既可．

连接数据库要连接池，就是connection对象要放在一个LinkedList里面，然后每个线程一个。这个这个List被封装在一个单例模式的对象里。线程要是共享connection，要是搞起并发来，一下子就挂了。

多线程连接数据库的连接池类：

public static class ConnectionPool

{

private static object locker = new object()

private static Dictionary<string, SqlConnection>Connections = null

public static SqlConnection GetConnection<T>() where T : class, new()

{

string databaseName = NA.Common.Extensions.GetDatabaseName<T>()

if (string.IsNullOrEmpty(databaseName))

return null

if (Connections == null)

{

lock (locker)

{

Connections = new Dictionary<string, SqlConnection>()

}

}

string connKey = FindFreeSqlConnection(databaseName)

if (connKey != null)

return Connections[connKey]

else

{

string strconn = NA.Common.Extensions.GetConnectionString<T>()

int poolSize = NA.Common.Extensions.GetConnectionPoolSize<T>()

lock (locker)

{

for (int i = 0i <poolSize++i)

{

SqlConnection conn = new SqlConnection(strconn)

conn.Open()

Connections.Add(databaseName + "_" + i.ToString(), conn)

conn.Close()

}

}

return Connections[FindFreeSqlConnection(databaseName)]

}

}

private static string FindFreeSqlConnection(string databaseName)

{

IEnumerable<string>connKeys = Connections.Keys.Where(item =>item.StartsWith(databaseName))

if (connKeys != null &&connKeys.Count() >0)

{

foreach (string key in connKeys)

{

if (Connections[key].State == ConnectionState.Closed)

return key

}

}

return null

}

}

附加上其中用到的三个方法：

internal static int GetConnectionPoolSize<T>() where T : class, new()

{

string database = GetDatabaseName<T>()

string[] poolSizeArray = ConfigurationManager.AppSettings["ConnectionsPoolSize"].Split('|')

if (poolSizeArray != null)

{

foreach (string sizeItem in poolSizeArray)

{

string[] sizeItemArray = sizeItem.Split(':')

if (database == sizeItemArray[0])

return int.Parse(sizeItemArray[1])

}

}

return 50

}

public static string GetConnectionString<T>() where T : class, new()

{

string tableName = GetTableName<T>()

string[] databaseArray = ConfigurationManager.AppSettings["DatabaseArray"].Split('|')

if (databaseArray != null)

{

foreach (string database in databaseArray)

{

string tableNameList = ConfigurationManager.AppSettings[database]

string[] tables = ConfigurationManager.AppSettings[database].Split('|')

if (tables != null &&tables.Length >0)

if (tables.Contains(tableName))

return ConfigurationManager.ConnectionStrings[database].ConnectionString

}

}

return string.Empty

}

public static string GetDatabaseName<T>() where T : class, new()

{

string tableName = GetTableName<T>()

string[] databaseArray = ConfigurationManager.AppSettings["DatabaseArray"].Split('|')

if (databaseArray != null)

{

foreach (string database in databaseArray)

{

string tableNameList = ConfigurationManager.AppSettings[database]

string[] tables = ConfigurationManager.AppSettings[database].Split('|')

if (tables != null &&tables.Length >0)

if (tables.Contains(tableName))

return database

}

}

return string.Empty

}

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