如何在.NET标准2.0中获得系统内存总量？

using System;
using System.Diagnostics;

namespace MemoryExample
{
    class Program
    {
        static void Main(string[] args)
        {
            // 获取当前进程的内存使用情况
            Process currentProcess = Process.GetCurrentProcess();
            long workingSet = currentProcess.WorkingSet64;

            Console.WriteLine("当前进程使用的物理内存大小：{0} bytes", workingSet);

            // 获取系统的总内存大小
            PerformanceCounter totalMemoryCounter = new PerformanceCounter("Memory", "Available Bytes", "");
            long totalMemory = totalMemoryCounter.RawValue;

            Console.WriteLine("系统的总内存大小：{0} bytes", totalMemory);
        }
    }
}