/// <summary>
/// 类的单例创建函数
/// </summary>
/// <param name="conStr"></param>
/// <returns></returns>
public static AccessDbHelper CreateInstance(string conStr)
{
// 当第一个线程运行到这里时，此时会对locker对象 "加锁"，
// 当第二个线程运行该方法时，首先检测到locker对象为"加锁"状态，该线程就会挂起等待第一个线程解锁
// lock语句运行完之后（即线程运行完之后）会对该对象"解锁"
// 双重锁定只需要一句判断就可以了
if (_accessDbHelper == null)
{
lock (_locker)
{
// 如果类的实例不存在则创建，否则直接返回
if (_accessDbHelper == null)
{
_accessDbHelper = new AccessDbHelper();
}
}
}
_accessDbHelper.ConStr = conStr;
GC.Collect(1);
return(_accessDbHelper);
}
/// <summary>
/// 执行一般sql语句，返回受影响的记录行数
/// </summary>
/// <param name="sql">sql语句</param>
/// <param name="prePms">变量的键值对集合</param>
/// <returns>受影响的记录行数</returns>
public int QueryInt(string sql, Dictionary <string, object> prePms = null)
{
SqlServerHelper _sqlServer = SqlServerHelper.CreateInstance(SqlConStr);
int i = 0;
while (i <= 2)
{
try
{
return(_sqlServer.QueryInt(sql, prePms));
}
catch (Exception ex)
{
i++;
Thread.Sleep(500);
continue;
throw ex;
}
}
AccessDbHelper _accessSever = AccessDbHelper.CreateInstance(AccessConStr);
return(_accessSever.QueryInt(sql, prePms));
}
/// <summary>
/// 泛型方法，根据where条件查询对应泛型的表中记录，并返回泛型列表
/// </summary>
/// <typeparam name="T">泛型，Model中数据表的对应类</typeparam>
/// <param name="where">where条件</param>
/// <returns>泛型列表</returns>
public List <T> QueryList <T>(string where = null)
{
SqlServerHelper _sqlServer = SqlServerHelper.CreateInstance(SqlConStr);
int i = 0;
while (i <= 2)
{
try
{
return(_sqlServer.QueryList <T>(where));
}
catch (Exception exc)
{
i++;
Thread.Sleep(500);
continue;
throw exc;
}
}
AccessDbHelper _accessSever = AccessDbHelper.CreateInstance(AccessConStr);
return(_accessSever.QueryList <T>(where));
}
/// <summary>
/// 泛型方法，根据对应操作和泛型列表执行对应数据库操作，返回对应操作影响的行数
/// </summary>
/// <typeparam name="T">泛型，Model中数据表的对应类</typeparam>
/// <param name="opration">数据操作：Insert、Update、Delete忽略大小写</param>
/// <param name="modelList">泛型列表</param>
/// <returns>影响的行数</returns>
public int QueryInt <T>(string opration, List <T> modelList)
{
SqlServerHelper _sqlServer = SqlServerHelper.CreateInstance(SqlConStr);
int i = 0;
while (i <= 2)
{
try
{
return(_sqlServer.QueryInt <T>(opration, modelList));
}
catch (Exception exc)
{
i++;
Thread.Sleep(500);
continue;
throw exc;
}
}
AccessDbHelper _accessSever = AccessDbHelper.CreateInstance(AccessConStr);
return(_accessSever.QueryInt <T>(opration, modelList));
}