静态类寿命

static 类在成员访问时被懒惰地初始化，并且在应用程序域的持续时间内存在。

void Main()
{
    Console.WriteLine("Static classes are lazily initialized");
    Console.WriteLine("The static constructor is only invoked when the class is first accessed");
    Foo.SayHi();

    Console.WriteLine("Reflecting on a type won't trigger its static .ctor");
    var barType = typeof(Bar);

    Console.WriteLine("However, you can manually trigger it with System.Runtime.CompilerServices.RuntimeHelpers");
    RuntimeHelpers.RunClassConstructor(barType.TypeHandle);
}

// Define other methods and classes here
public static class Foo
{
    static Foo()
    {
        Console.WriteLine("static Foo.ctor");
    }
    public static void SayHi()
    {
        Console.WriteLine("Foo: Hi");
    }
}
public static class Bar
{
    static Bar()
    {
        Console.WriteLine("static Bar.ctor");
    }
}