wcf使用单利模式创建类发生异常

Question

我在wcf服务中.自定义一个类目的是连接数据库,这个类是通过单利模式创建的.但是在客户端调用的时候,这个类竟然无法创建对象.请wcf高手看看.

 public class TestSer : ITestSer
{
...
public LoginParam GetLoginObj()
{
LoginParam loginobj = null;
MySQLHelper sqlhelper = MySQLHelper.CreatInstance();//自定义类用于连接数据库
string sqlstr = "select * from c_task";
int execcount = 0;
try
{
execcount = sqlhelper.ExecuteMySqlNonQuery(sqlstr, System.Data.CommandType.Text);
}
catch (Exception)
{
execcount = -1;
}

        if (execcount < 0)
        {
            loginobj = null;
        }
                     else
        {
            //这里由于没有创建数据库,所以暂时用假数据.
            loginobj = new LoginParam();
            loginobj.TaskID = "123450";
            loginobj.AcceptLanguage = "1";
            loginobj.LoginUrl = "http://www.baidu.com"; ;
            loginobj.UserName = "张三";
            loginobj.PassWord = "954471364";
        }
        return loginobj;
    }
}

Answer 1

public class TestSer : ITestSer
{
...
public LoginParam GetLoginObj()
{
LoginParam loginobj = null;
MySQLHelper sqlhelper = MySQLHelper.CreatInstance();//自定义类用于连接数据库
string sqlstr = "select * from c_task";
int execcount = 0;
try
{
execcount = sqlhelper.ExecuteMySqlNonQuery(sqlstr, System.Data.CommandType.Text);
}
catch (Exception)
{
execcount = -1;
}

        if (execcount < 0)
        {
            loginobj = null;
        }
                     else
        {
            //这里由于没有创建数据库,所以暂时用假数据.
            loginobj = new LoginParam();
            loginobj.TaskID = "123450";
            loginobj.AcceptLanguage = "1";
            loginobj.LoginUrl = "http://www.baidu.com"; ;
            loginobj.UserName = "张三";
            loginobj.PassWord = "954471364";
        }
        return loginobj;
    }

}