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C#中用API实现MP3等音频文件的播放类

2023-05-14 16:26:34
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C#没有提供播放MP3等音频文件的类,要编写播放MP3等音频文件程序,必须使用第三方控件或类。本文使用API函数mciSendString,编写一个播放MP3等音频文件的类。

  具体源码如下:

  一、使用API函数mciSendString构成的媒体播放类。

using System;
using System.Runtime.InteropServices;
using System.Text;
using System.IO ;
namespace clsMCIPlay
{
 /// <summary>
 /// clsMci 的摘要说明。
 /// </summary>
 public class clsMCI
 {
  public clsMCI()
  {
   //
   // TODO: 在此处添加构造函数逻辑
   //
  }

  //定义API函数使用的字符串变量
  [MarshalAs(UnmanagedType.ByValTStr,SizeC)]
  private string Name = "" ;
  [MarshalAs(UnmanagedType.ByValTStr,SizeC)]
  private string durLength = "" ;
  [MarshalAs(UnmanagedType.LPTStr,SizeC)]
  private string TemStr ="";
  int ilong;
  //定义播放状态枚举变量
  public enum State
  {
   mPlaying = 1,
   mPuase = 2,
   mStop = 3
  };
  //结构变量
  public struct structMCI
  {
   public bool bMut;
   public int iDur;
   public int iPos;
   public int iVol;
   public int iBal;
   public string iName;
   public State state;
  };

  public structMCI mc =new structMCI() ;

  //取得播放文件属性
  public string FileName
  {
   get
   {
    return mc.iName;
   }
   set
   {
    //ASCIIEncoding asc = new ASCIIEncoding();
    try
    {
     TemStr ="";
     TemStr = TemStr.PadLeft(127,Convert.ToChar(" "));
     Name = Name.PadLeft(260,Convert.ToChar(" ")) ;
     mc.iName = value;
     ilong = APIClass.GetShortPathName(mc.iName,Name, Name.Length);
     Name = GetCurrPath(Name);
     //Name = "open " + Convert.ToChar(34) + Name + Convert.ToChar(34) + " alias media";
     Name = "open " + Convert.ToChar(34) + Name + Convert.ToChar(34) + " alias media";
     ilong = APIClass.mciSendString("close all", TemStr, TemStr.Length , 0);
     ilong = APIClass.mciSendString( Name, TemStr, TemStr.Length, 0);
     ilong = APIClass.mciSendString("set media time format milliseconds", TemStr, TemStr.Length , 0);
     mc.state = State.mStop;
    }
    catch
    {
     MessageBox.Show("出错错误!");
    }
   }
  }
  //播放
  public void play()
  {
   TemStr = "";
   TemStr = TemStr.PadLeft(127,Convert.ToChar(" "));
   APIClass.mciSendString("play media", TemStr, TemStr.Length , 0);
   mc.state = State.mPlaying ;
  }
  //停止
  public void StopT()
  {
   TemStr = "";
   TemStr = TemStr.PadLeft(128,Convert.ToChar(" "));
   ilong = APIClass.mciSendString("close media", TemStr, 128, 0);
   ilong = APIClass.mciSendString("close all", TemStr, 128, 0);
   mc.state = State.mStop ;
  }

  public void Puase()
  {
   TemStr = "";
   TemStr = TemStr.PadLeft(128,Convert.ToChar(" "));
   ilong = APIClass.mciSendString("pause media", TemStr, TemStr.Length, 0);
   mc.state = State.mPuase ;
  }
  private string GetCurrPath(string name)
  {
   if(name.Length <1) return "";
   name = name.Trim();
   name = name.Substring(0,name.Length-1);
   return name;
  }
  //总时间
  public int Duration
  {
   get
   {
    durLength = "";
    durLength = durLength.PadLeft(128,Convert.ToChar(" ")) ;
    APIClass.mciSendString("status media length", durLength, durLength.Length, 0);
    durLength = durLength.Trim();
    if(durLength == "") return 0;
    return (int)(Convert.ToDouble(durLength) / 1000f);
   }
  }

  //当前时间
  public int CurrentPosition
  {
   get
   {
    durLength = "";
    durLength = durLength.PadLeft(128,Convert.ToChar(" ")) ;
    APIClass.mciSendString("status media position", durLength, durLength.Length, 0);
    mc.iPos = (int)(Convert.ToDouble(durLength) / 1000f);
    return mc.iPos;
   }
  }
 }

 public class APIClass
 {
  [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
  );
 }
}

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