C#中用API实现MP3等音频文件的播放类

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,SizeConst=260)] private string Name = "" ; [MarshalAs(UnmanagedType.ByValTStr,SizeConst=128)] private string durLength = "" ; [MarshalAs(UnmanagedType.LPTStr,SizeConst=128)] 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 ); 　 } }

二、用于测试媒体播放类的简单代码：

using System; using System.Drawing; using System.Collections; using System.ComponentModel; using System.Windows.Forms; using System.Data; using System.Runtime.InteropServices; using System.Text; using System.IO ; using clsMCIPlay; namespace MCIPlay { 　 /// <summary> 　 /// Form1 的摘要说明。 　 /// </summary> 　 public class Form1 : System.Windows.Forms.Form 　 { private System.ComponentModel.IContainer components; private System.Windows.Forms.Timer timer1; private System.Windows.Forms.Button Play; private System.Windows.Forms.Button Stop; private System.Windows.Forms.Button Puase; private System.Windows.Forms.Label PlayFileName; private System.Windows.Forms.Label Duration; private System.Windows.Forms.Label CurrentPosition; private System.Windows.Forms.OpenFileDialog openFileDialog1; private System.Windows.Forms.Button BrowserFile; clsMCI mp = new clsMCI(); public Form1() { 　 // 　 // Windows 窗体设计器支持所必需的 　 // 　 InitializeComponent(); 　 // 　 // TODO: 在 InitializeComponent 调用后添加任何构造函数代码 　 // } /// <summary> /// 清理所有正在使用的资源。 /// </summary> protected override void Dispose( bool disposing ) { 　 if( disposing ) 　 { if (components != null) { 　 components.Dispose(); } 　 } 　 base.Dispose( disposing ); } #region Windows 窗体设计器生成的代码 /// <summary> /// 设计器支持所需的方法 - 不要使用代码编辑器修改 /// 此方法的内容。 /// </summary> private void InitializeComponent() { 　 this.components = new System.ComponentModel.Container(); 　 this.Play = new System.Windows.Forms.Button(); 　 this.PlayFileName = new System.Windows.Forms.Label(); 　 this.Duration = new System.Windows.Forms.Label(); 　 this.Stop = new System.Windows.Forms.Button(); 　 this.Puase = new System.Windows.Forms.Button(); 　 this.CurrentPosition = new System.Windows.Forms.Label(); 　 this.timer1 = new System.Windows.Forms.Timer(this.components); 　 this.openFileDialog1 = new System.Windows.Forms.OpenFileDialog(); 　 this.BrowserFile = new System.Windows.Forms.Button(); 　 this.SuspendLayout(); 　 // 　 // Play 　 // 　 this.Play.Location = new System.Drawing.Point(102, 243); 　 this.Play.Name = "Play"; 　 this.Play.Size = new System.Drawing.Size(78, 24); 　 this.Play.TabIndex = 0; 　 this.Play.Text = "Play"; 　 this.Play.Click += new System.EventHandler(this.Play_Click); 　 // 　 // PlayFileName 　 // 　 this.PlayFileName.AutoSize = true; 　 this.PlayFileName.Location = new System.Drawing.Point(12, 15); 　 this.PlayFileName.Name = "PlayFileName"; 　 this.PlayFileName.Size = new System.Drawing.Size(0, 17); 　 this.PlayFileName.TabIndex = 1; 　 // 　 // Duration 　 // 　 this.Duration.AutoSize = true; 　 this.Duration.Location = new System.Drawing.Point(15, 51); 　 this.Duration.Name = "Duration"; 　 this.Duration.Size = new System.Drawing.Size(0, 17); 　 this.Duration.TabIndex = 2; 　 // 　 // Stop 　 // 　 this.Stop.Location = new System.Drawing.Point(282, 243); 　 this.Stop.Name = "Stop"; 　 this.Stop.Size = new System.Drawing.Size(81, 24); 　 this.Stop.TabIndex = 3; 　 this.Stop.Text = "Stop"; 　 this.Stop.Click += new System.EventHandler(this.Stop_Click); 　 // 　 // Puase 　 // 　 this.Puase.Location = new System.Drawing.Point(198, 243); 　 this.Puase.Name = "Puase"; 　 this.Puase.Size = new System.Drawing.Size(72, 24); 　 this.Puase.TabIndex = 4; 　 this.Puase.Text = "Puase"; 　 this.Puase.Click += new System.EventHandler(this.Puase_Click); 　 // 　 // CurrentPosition 　 // 　 this.CurrentPosition.AutoSize = true; 　 this.CurrentPosition.Location = new System.Drawing.Point(15, 87); 　 this.CurrentPosition.Name = "CurrentPosition"; 　 this.CurrentPosition.Size = new System.Drawing.Size(0, 17); 　 this.CurrentPosition.TabIndex = 5; 　 // 　 // timer1 　 // 　 this.timer1.Enabled = true; 　 this.timer1.Interval = 1000; 　 this.timer1.Tick += new System.EventHandler(this.timer1_Tick); 　 // 　 // BrowserFile 　 // 　 this.BrowserFile.Location = new System.Drawing.Point(312, 165); 　 this.BrowserFile.Name = "BrowserFile"; 　 this.BrowserFile.Size = new System.Drawing.Size(87, 24); 　 this.BrowserFile.TabIndex = 6; 　 this.BrowserFile.Text = "SelectFile"; 　 this.BrowserFile.Click += new System.EventHandler(this.BrowserFile_Click); 　 // 　 // Form1 　 // 　 this.AutoScaleBaseSize = new System.Drawing.Size(6, 14); 　 this.ClientSize = new System.Drawing.Size(433, 287); 　 this.Controls.Add(this.BrowserFile); 　 this.Controls.Add(this.CurrentPosition); 　 this.Controls.Add(this.Puase); 　 this.Controls.Add(this.Stop); 　 this.Controls.Add(this.Duration); 　 this.Controls.Add(this.PlayFileName); 　 this.Controls.Add(this.Play); 　 this.Name = "Form1"; 　 this.Text = "Form1"; 　 this.ResumeLayout(false); } #endregion /// <summary> /// 应用程序的主入口点。 /// </summary> [STAThread] static void Main() { 　 Application.Run(new Form1()); } //选择MP3文件播放 private void Play_Click(object sender, System.EventArgs e) { 　 try 　 { mp.play(); 　 } 　 catch 　 { MessageBox.Show("出错错误!"); 　 } } //暂停播放 private void Puase_Click(object sender, System.EventArgs e) { 　 try 　 { mp.Puase(); 　 } 　 catch 　 { MessageBox.Show("出错错误!"); 　 } } //停止播放 private void Stop_Click(object sender, System.EventArgs e) { 　 try 　 { mp.StopT(); 　 } 　 catch 　 { MessageBox.Show("出错错误!"); 　 } } //每秒显示一次播放进度 private void timer1_Tick(object sender, System.EventArgs e) { 　 CurrentPosition.Text = mp.CurrentPosition.ToString(); } //浏览文件 private void BrowserFile_Click(object sender, System.EventArgs e) { 　 try 　 { openFileDialog1.Filter = "*.mp3|*.mp3"; openFileDialog1.FileName = ""; if(openFileDialog1.ShowDialog() == DialogResult.OK) { 　 mp.FileName = openFileDialog1.FileName ; 　 PlayFileName.Text = openFileDialog1.FileName ; 　 Duration.Text = mp.Duration.ToString() ; } 　 } 　 catch 　 { MessageBox.Show("出错错误!"); 　 } } 　 } }