add XianTu

XianTu/Singleton.cs

@@ -0,0 +1,21 @@
+
+
+namespace XianTu;
+
+public class Singleton<T> where T : new()
+{
+    public static T Instance
+    {
+        get
+        {
+            var flag = _msInstance == null;
+            if (flag)
+            {
+                _msInstance = new T();
+            }
+            return _msInstance;
+        }
+    }
+
+    private static T _msInstance;
+}