static void Main(string[] args)
{
string sql = "select id from tb_area";
object obj = SqlHelper.ExecuteScalar(sql);
Console.WriteLine(obj);
// 不能创建实例 应为默认的构造函数被私有化了
// SingletonClass1 sgt1 = new SingletonClass1();
//不管你调用几次,都只能创建一个对象
/* SingletonClass1 sgt1 = SingletonClass1.CreateInstance();
* SingletonClass1 sgt2 = SingletonClass1.CreateInstance();
* SingletonClass1 sgt3 = SingletonClass1.CreateInstance();*/
/* //使用循环创建多个线程来测试
* for (int i = 0; i < 1000; i++)
* {
* //创建一个线程
* Thread t1 = new Thread(new ThreadStart(()=> {
* SingletonClass1 sgt = SingletonClass1.CreateInstance();
* }));
* t1.Start();
* }*/
for (int i = 0; i < 10; i++)
{
//创建线程
Thread t2 = new Thread(new ThreadStart(() =>
{
SingletonClass2 sgt2 = SingletonClass2.CreateInstance();
sgt2.SayHi();
}));
t2.Start();//启动线程
}
string txt = "123";
//调用自定义的类库
string cipher = TekinFLib.Security.MyHash.GetHash(txt);
Console.WriteLine($" {txt}加密后的字符串为{cipher}");
Console.WriteLine("OK");
Console.ReadKey();
}
private static readonly Object syn = new object();//定义一个对象用于加锁
public static SingletonClass2 CreateInstance()
{
//注意这里的双重if判断 来确保只能创建一次 且性能最优化
if (null == _instance)
{
lock (syn)
{
//在锁住后再判断是否需要创建,这样就确保只能创建一次
if (_instance == null)
{
_instance = new SingletonClass2();
}
}
}
return(_instance);
}