    [DllImport("kernel32.dll")]
    static extern uint SetThreadExecutionState(ExecutionFlag flags);

    [Flags]
    enum ExecutionFlag : uint
    {
        System = 0x00000001,
        Display = 0x00000002,
        Continuous = 0x80000000,
    }

它就一個flags參數(shù)，這個參數(shù)有三個選項(xiàng)，可以組合使用。主要說明如下：

只使用Continuous參數(shù)時，則是恢復(fù)系統(tǒng)休眠策略。
不使用Continuous參數(shù)時，實(shí)現(xiàn)阻止系統(tǒng)休眠或顯示器關(guān)閉一次
組合使用Continuous參數(shù)時，實(shí)現(xiàn)阻止系統(tǒng)休眠或顯示器關(guān)閉至線程終止

因此，它一共有三種使用方式，這里我就封裝了一下：

    class SystemSleepManagement
    {
        //定義API函數(shù)
        [DllImport("kernel32.dll")]
        static extern uint SetThreadExecutionState(ExecutionFlag flags);

        [Flags]
        enum ExecutionFlag : uint
        {
            System = 0x00000001,
            Display = 0x00000002,
            Continuous = 0x80000000,
        }

        /// <summary>
        ///阻止系統(tǒng)休眠，直到線程結(jié)束恢復(fù)休眠策略
        /// </summary>
        /// <param name="includeDisplay">是否阻止關(guān)閉顯示器</param>
        public static void PreventSleep(bool includeDisplay = false)
        {
            if (includeDisplay)
                SetThreadExecutionState(ExecutionFlag.System | ExecutionFlag.Display | ExecutionFlag.Continuous);
            else
                SetThreadExecutionState(ExecutionFlag.System | ExecutionFlag.Continuous);
        }

        /// <summary>
        ///恢復(fù)系統(tǒng)休眠策略
        /// </summary>
        public static void RestoreSleep()
        {
            SetThreadExecutionState(ExecutionFlag.Continuous);
        }

        /// <summary>
        ///重置系統(tǒng)休眠計時器
        /// </summary>
        /// <param name="includeDisplay">是否阻止關(guān)閉顯示器</param>
        public static void ResetSleepTimer(bool includeDisplay = false)
        {
            if (includeDisplay)
                SetThreadExecutionState(ExecutionFlag.System | ExecutionFlag.Display);
            else
                SetThreadExecutionState(ExecutionFlag.System);
        }
    }

因此，要實(shí)現(xiàn)下載時阻止程序休眠，則有兩種實(shí)現(xiàn)方式：