http://yacki.iteye.com/blog/1967119
using System;
using System.Collections.Generic;
using System.Text;
using System.Data.SQLite;
using System.Threading;
using System.Data;
namespace DataAccess
{
/////////////////
public sealed class SqliteConn
{
private bool m_disposed;
private static Dictionary<String, SQLiteConnection> connPool = new Dictionary<string, SQLiteConnection>();
private static Dictionary<String, ReaderWriterLock> rwl = new Dictionary<String, ReaderWriterLock>();
private static readonly SqliteConn instance = new SqliteConn();
private static string DEFAULT_NAME = "LOCAL";
#region Init
// 使用单例，解决初始化与销毁时的问题
private SqliteConn()
{
rwl.Add("LOCAL", new ReaderWriterLock());
rwl.Add("DB1", new ReaderWriterLock());
connPool.Add("LOCAL", CreateConn("\\local.db"));
connPool.Add("DB1", CreateConn("\\db1.db"));
Console.WriteLine("INIT FINISHED");
}
private static SQLiteConnection CreateConn(string dbName)
{
SQLiteConnection _conn = new SQLiteConnection();
try
{
string pstr = "pwd";
SQLiteConnectionStringBuilder connstr = new SQLiteConnectionStringBuilder();
connstr.DataSource = Environment.CurrentDirectory + dbName;
_conn.ConnectionString = connstr.ToString();
_conn.SetPassword(pstr);
_conn.Open();
return _conn;
}
catch (Exception exp)
{
Console.WriteLine("===CONN CREATE ERR====\r\n{0}", exp.ToString());
return null;
}
}
#endregion
#region Destory
// 手动控制销毁，保证数据完整性
public void Dispose()
{
Dispose(true);
GC.SuppressFinalize(this);
}
protected void Dispose(bool disposing)
{
if (!m_disposed)
{
if (disposing)
{
// Release managed resources
Console.WriteLine("关闭本地DB连接...");
CloseConn();
}
// Release unmanaged resources
m_disposed = true;
}
}
~SqliteConn()
{
Dispose(false);
}
public void CloseConn()
{
foreach (KeyValuePair<string, SQLiteConnection> item in connPool)
{
SQLiteConnection _conn = item.Value;
String _connName = item.Key;
if (_conn != null && _conn.State != ConnectionState.Closed)
{
try
{
_conn.Close();
_conn.Dispose();
_conn = null;
Console.WriteLine("Connection {0} Closed.", _connName);
}
catch (Exception exp)
{
Console.WriteLine("严重异常: 无法关闭本地DB {0} 的连接。", _connName);
exp.ToString();
}
finally
{
_conn = null;
}
}
}
}
#endregion
#region GetConn
public static SqliteConn GetInstance()
{
return instance;
}
public SQLiteConnection GetConnection(string name)
{
SQLiteConnection _conn = connPool[name];
try
{
if (_conn != null)
{
Console.WriteLine("TRY GET LOCK");
//加锁，直到释放前，其它线程无法得到conn
rwl[name].AcquireWriterLock(3000);
Console.WriteLine("LOCK GET");
return _conn;
}
}
catch (Exception exp)
{
Console.WriteLine("===GET CONN ERR====\r\n{0}", exp.StackTrace);
}
return null;
}
public void ReleaseConn(string name)
{
try
{
//释放
Console.WriteLine("RELEASE LOCK");
rwl[name].ReleaseLock();
}
catch (Exception exp)
{
Console.WriteLine("===RELEASE CONN ERR====\r\n{0}", exp.StackTrace);
}
}
public SQLiteConnection GetConnection()
{
return GetConnection(DEFAULT_NAME);
}
public void ReleaseConn()
{
ReleaseConn(DEFAULT_NAME);
}
#endregion
}
}
////////////////////////
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
調用的代碼如下：
SQLiteConnection conn = null;
try
{
conn = SqliteConn.GetInstance().GetConnection();
//在这里写自己的代码
}
finally
{
SqliteConn.GetInstance().ReleaseConn();
}
值得注意的是，每次申請連接後，必須使用ReleaseConn方法釋放，否則其它線程就再也無法得到連接了。
安全起見，在作者寫的這個工具類中，啟用了最嚴格的讀寫鎖限制（即在寫入時無法讀取）。如果數據讀取頻繁，讀者亦可開發一個得到只讀連接的方法以提高性能。