Unity中如何获取SystemClock.elapsedRealtime()实现防篡改离线游戏计时

核心思路 #

系统自重启后的运行时长（Uptime）是独立于系统时间的指标，修改系统时间不会改变它。我们可以通过各平台原生API获取该值，再结合PlayerPrefs记录游戏每次退出时的Uptime，重启后计算差值即可得到游戏累计运行时间——这就是你看到的Elapsed_stamp变量的作用逻辑。

各平台Uptime获取实现 #

Windows平台 #

调用kernel32.dll的GetTickCount64()获取系统启动以来的毫秒数：

using System.Runtime.InteropServices;

public static class SystemUptime
{
    [DllImport("kernel32.dll")]
    private static extern ulong GetTickCount64();

    public static ulong GetUptimeMilliseconds()
    {
        return GetTickCount64();
    }
}

macOS/Linux平台 #

用Mono的SystemInformation直接获取，或通过系统原生接口实现：

using System.Windows.Forms;

public static ulong GetUptimeMilliseconds()
{
    return (ulong)SystemInformation.TickCount;
}

macOS原生调用版本：

using System.Runtime.InteropServices;

public static class SystemUptime
{
    [DllImport("libc.dylib")]
    private static extern int sysctlbyname(string name, IntPtr oldp, ref uint oldlen, IntPtr newp, uint newlen);

    public static ulong GetUptimeMilliseconds()
    {
        uint len = sizeof(long);
        IntPtr ptr = Marshal.AllocHGlobal((int)len);
        sysctlbyname("kern.boottime", ptr, ref len, IntPtr.Zero, 0);
        long bootTime = Marshal.ReadInt64(ptr);
        Marshal.FreeHGlobal(ptr);
        long now = DateTimeOffset.UtcNow.ToUnixTimeSeconds();
        return (ulong)(now - bootTime) * 1000;
    }
}

Android平台 #

调用Android系统的SystemClock.elapsedRealtime()：

using UnityEngine;

public static ulong GetUptimeMilliseconds()
{
    AndroidJavaClass systemClock = new AndroidJavaClass("android.os.SystemClock");
    return (ulong)systemClock.CallStatic<long>("elapsedRealtime");
}

iOS平台 #

通过mach_absolute_time()转换为实际运行毫秒数：

using System.Runtime.InteropServices;
using UnityEngine;

public static class SystemUptime
{
    [DllImport("libSystem.dylib")]
    private static extern uint mach_absolute_time();

    [DllImport("libSystem.dylib")]
    private static extern void mach_timebase_info(ref TimebaseInfo info);

    private struct TimebaseInfo
    {
        public uint numer;
        public uint denom;
    }

    public static ulong GetUptimeMilliseconds()
    {
        TimebaseInfo info = new TimebaseInfo();
        mach_timebase_info(ref info);
        ulong absoluteTime = mach_absolute_time();
        ulong nanoseconds = absoluteTime * (ulong)info.numer / (ulong)info.denom;
        return nanoseconds / 1000000;
    }
}

结合PlayerPrefs实现计时器逻辑 #

每次游戏退出时记录当前Uptime和累计时间，启动时计算差值更新总时长：

using UnityEngine;

public class GameTimer : MonoBehaviour
{
    private const string Prefs_UptimeStamp = "Elapsed_stamp";
    private const string Prefs_TotalGameTime = "Total_Game_Time";

    private ulong _lastUptime;
    private double _totalGameTime;

    void Start()
    {
        if (PlayerPrefs.HasKey(Prefs_UptimeStamp) && PlayerPrefs.HasKey(Prefs_TotalGameTime))
        {
            _lastUptime = (ulong)PlayerPrefs.GetInt(Prefs_UptimeStamp);
            _totalGameTime = PlayerPrefs.GetFloat(Prefs_TotalGameTime);
        }
        else
        {
            _lastUptime = SystemUptime.GetUptimeMilliseconds();
            _totalGameTime = 0;
        }
    }

    void Update()
    {
        ulong currentUptime = SystemUptime.GetUptimeMilliseconds();
        if (currentUptime > _lastUptime)
        {
            double delta = (currentUptime - _lastUptime) / 1000.0;
            _totalGameTime += delta;
            _lastUptime = currentUptime;
        }
    }

    void OnApplicationQuit()
    {
        PlayerPrefs.SetInt(Prefs_UptimeStamp, (int)_lastUptime);
        PlayerPrefs.SetFloat(Prefs_TotalGameTime, (float)_totalGameTime);
        PlayerPrefs.Save();
    }

    public double GetTotalGameTime()
    {
        return _totalGameTime;
    }
}

关键注意事项 #

• 用Application.platform做平台分支判断，确保各平台调用对应Uptime获取方法。
• PlayerPrefs存储为明文，可通过简单异或加密存储值，防止玩家直接修改文件篡改时间。
• 优先使用64位返回值，避免32位Uptime变量溢出问题。

内容的提问来源于stack exchange，提问作者Xordaraxus