使用MCI接口播放音乐

 在C#中播放音乐主要有三种方式：1、System.Media.SoundPlay;2、MCI接口;3、MediaPlayer控件。SoundPlay是专门用来播放声音的,即.wav文件,使用方法比较简单。MediaPlayer控件是系统自带的播放器，关于它的介绍已经很多了。

      今天我想为大家介绍的MCI接口,关于MCI接口的介绍，大家可以参考MSDN,这里我们只是介绍具体的用法。首先，我们需要定义一个枚举类型来描述播放器的状态。

  public enum PlayState : byte    {        Playing = 1,        Puased = 2,        Stopped = 3,    }

   接下来，为了便于后面的继续，我们对MCI接口做了一个封装：

  class WAPI    {        [DllImport("kernel32.dll", CharSet = CharSet.Auto)]        public static extern int GetShortPathName(        string lpszLongPath,        string shortFile,        int cchBuffer        );        [DllImport("winmm.dll", EntryPoint = "mciSendString", CharSet = CharSet.Auto)]        public static extern int mciSendString(        string lpstrCommand,        string lpstrReturnString,        int uReturnLength,        int hwndCallback        );    }

  关于这两个API函数，大家可以在MSDN找到相关说明。接下来，我们来构建播放器的类：

 public class MPlayer    {        //定义歌曲地址        private string Url = string.Empty;        //定义歌曲结构的实例        private Media m = new Media();        //构造函数        public MPlayer()        {            m.Position = 0;            m.State = PlayState.Stopped;            m.Volume = 0;            m.Speed = 1000;            m.Duration = 0;        }        //FileName属性        public string FileName        {            set            {                Url = string.Empty;                string Name = value;                m.Position = 0;                Url = Url.PadLeft(260, ' ');                WAPI.GetShortPathName(Name, Url, Url.Length);                Url = GetFileUrl(Url);                InitDevice();            }        }        //设备初始化        private void InitDevice()        {            string DeviceID = GetDeviceID(Url);//返回类型             WAPI.mciSendString("Close All", null, 0, 0);//关闭所有设备            if (DeviceID != "RealPlay")            {                string MciCommand = String.Format("Open {0} type {1} Alias Media", Url, DeviceID);                WAPI.mciSendString(MciCommand, null, 0, 0);//初始化设备                m.State = PlayState.Stopped;            }        }        //获取设备ID        private string GetDeviceID(string Url)        {            string Result = string.Empty;            Url = Url.ToUpper().Trim();            if (Url.Length < 3)            {                return Url;            }            switch (Url.Substring(Url.Length - 3))            {                case "MID":                    Result = "Sequencer";                    break;                case "RMI":                    Result = "Sequencer";                    break;                case "IDI":                    Result = "Sequencer";                    break;                case "WAV":                    Result = "Waveaudio";                    break;                case "ASX":                    Result = "MPEGVideo2";                    break;                case "IVF":                    Result = "MPEGVideo2";                    break;                case "LSF":                    Result = "MPEGVideo2";                    break;                case "LSX":                    Result = "MPEGVideo2";                    break;                case "P2V":                    Result = "MPEGVideo2";                    break;                case "WAX":                    Result = "MPEGVideo2";                    break;                case "WVX":                    Result = "MPEGVideo2";                    break;                case ".WM":                    Result = "MPEGVideo2";                    break;                case "WMX":                    Result = "MPEGVideo2";                    break;                case "WMP":                    Result = "MPEGVideo2";                    break;                case ".RM":                    Result = "RealPlay";                    break;                case "RAM":                    Result = "RealPlay";                    break;                case ".RA":                    Result = "RealPlay";                    break;                case "MVB":                    Result = "RealPlay";                    break;                default:                    Result = "MPEGVideo";                    break;            }            return Result;        }        //得到当前路径        private string GetFileUrl(string FileName)        {            FileName = FileName.Trim();//去掉空格            if (FileName.Length > 1)//判断是否为空(name包含'\0')            {                FileName = FileName.Substring(0, FileName.Length - 1);//去掉'\0'            }            return FileName;        }        //判断初始化后设备是否准备好接受命令        public bool IsReady()        {            string Ready = new string(' ', 10);            WAPI.mciSendString("Status Media Ready", Ready, Ready.Length, 0);            Ready = Ready.Trim();            if (Ready.Contains("true"))            {                return true;            }            else            {                return false;            }        }        //播放         public void Play()        {            if (m.State != PlayState.Playing)            {                WAPI.mciSendString("Play Media", null, 0, 0);                m.State = PlayState.Playing;            }        }        //停止         public void Stop()        {            if (m.State != PlayState.Stopped)            {                WAPI.mciSendString("Stop Media", null, 0, 0);                m.State = PlayState.Stopped;            }        }        //暂停        public void Puase()        {            if (m.State == PlayState.Playing)            {                WAPI.mciSendString("Pause Media", null, 0, 0);                m.State = PlayState.Puased;            }        }        //恢复播放        public void Resume()        {            int RefInt = WAPI.mciSendString("Resume Media", null, 0, 0);            m.State = PlayState.Playing;        }        //属性Duration        public int Duration        {            get            {                WAPI.mciSendString("Set Media Time Format Milliseconds", null, 0, 0);//设置时间格式单位为毫秒                m.Duration = GetDuration();                return m.Duration;            }        }        private int GetDuration()        {            string Length = string.Empty;            Length = Length.PadLeft(20, ' ');//设置定长字符串long是19位,足够表示时间了            WAPI.mciSendString("Status Media Length", Length, Length.Length, 0);            Length = Length.Trim();            if (Length.Length > 1)            {                Length = Length.Substring(0, Length.Length - 1);                return (int)(long.Parse(Length) / 1000);            }            return 0;        }        //属性State        public PlayState State        {            get            {                return m.State;            }        }        public string PositionString        {            get            {                string mm = (this.Position / 60).ToString("00");                string ss = (this.Position % 60).ToString("00");                return mm + ":" + ss;            }        }        public string DurationString        {            get            {                string mm = (this.Duration / 60).ToString("00");                string ss = (this.Duration % 60).ToString("00");                return mm + ":" + ss;            }        }        //设置获取当前时间         public int Position        {            get            {                string Position = string.Empty;                Position = Position.PadLeft(20, ' ');//long表示范围是19位                WAPI.mciSendString("Status Media Position", Position, Position.Length, 0);                Position = Position.Trim();                if (Position.Length > 1)                {                    m.Position = (int)(long.Parse(Position) / 1000);//以秒返回                }                return m.Position;            }            set            {                string Command = String.Format("Seek Media to {0}", value*1000);                WAPI.mciSendString(Command, null, 0, 0);//使播放停止                m.State = PlayState.Stopped;                m.Position = value*1000;                Play();            }        }        //设置静音        public void VolumeOff(bool IsOff)        {            string SetOnOff = string.Empty;            if (IsOff)                SetOnOff = "Off";            else                SetOnOff = "On";            string MciCommand = String.Format("Set Audio Media {0}", SetOnOff);            WAPI.mciSendString(MciCommand, null, 0, 0);        }        //Volume        public int Volume        {            get            {                return m.Volume;            }            set            {                if (value >= 0)                {                    m.Volume = value;                    string MciCommand = String.Format("Set Audio Media Volume To {0}", m.Volume);                    WAPI.mciSendString(MciCommand, null, 0, 0);                }            }        }        //定义歌曲结构        private struct Media        {            public int Position;            public PlayState State;            public int Volume;            public int Speed;            public int Duration;        }    }

 关于这个类，我想说两点，第一：在设置Position属性即歌曲的进度时,我们对其赋值为value*1000.为什么要乘1000呢？因为在获取Position时为们做了单位转换，除了1000，所以这里要乘以1000，否则程序将不起作用。第二：使用MCI播放的时候，经常会发出嘶嘶的杂音，我的解决办法是，在播放前设置歌曲进度为1秒，即歌曲并不从头开始播放，这样就可以跳过去了。

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文章用的是别人的，我觉得好东西应该分享出来。——来自一个技术宅的IT程序猿