实例解析使用Java实现基本的音频播放器的编写要点

 Java音频播放，因为必须依赖到本地环境，所以JAVA在音频处理方面优势不大,或者说打从Java体系开发时就没太多的考虑音频播放因素，要知道最早的Java 1.1版本中，没有后来的javax.sound包，音频只能通过Applet包调取……

  遗憾的是，在图形程序开发中，我们的程序却又难免要使用到背景音乐、效果音等配合图像操作，哎，这实在是Sun大神给我们开的一个不打不小的玩笑。万幸后来Sun大神开眼，提供了javax.sound包，才解救我们于水深火热当中~

 但是继之而来的问题是，在javax.sound包的使用中，如同Java多媒体工具类的通病般，并没有提供十分完善的释放机制。如果我们做Windows 开发，调用MediaPlayer反复N次可能没也什么大碍，但在Java中，如果音频程序反复运行的话,极容易出现内存累计损耗的情况,以至于最后抛出一个java.lang.OutOfMemoryError,然后……程序就挂了，用户就傻了，我们就疯了……

这已经是“是可忍孰不可忍 ”的问题了，有鉴于此，所以在本人的Loonframework框架开发中，二次整合了sound下的相关方法，力求以最简单的代码，做出最完善的音频控制类。在Loonframework-game还没有大成的现在，先摘录一部分方法，以供各位看官——拍砖！

对应网络资源调用，在Loonframework中建立了自己的uri用类，基本内容如下：
(其中StreamHelper为Loonframework自己的流媒体控制类,getHttpStream方法请自行替换。)

package org.loon.framework.game.net;

import org.loon.framework.game.helper.StreamHelper;


public class URI ...{

  //传输协议类型
  public static final int _L_URI_HTTP = 1;

  public static final int _L_URI_UDP = 2;

  private String _uri;

  private int _type;

  
  public URI(String uri, int type) ...{
    _uri = new String(uri);
    _type = type;
  }

  
  public URI(String uri) ...{
    _uri = new String(uri);
    _type = URI._L_URI_HTTP;
  }

  
  public byte[] getData() ...{
    if (_uri == null) ...{
      return null;
    }
    return StreamHelper.getHttpStream(_uri);
  }

  public String getURI() ...{
    return _uri;
  }

  public int getType() ...{
    return _type;
  }

}

在Loonframework框架中,定制了一个基础的SoundData类,用以统一管理音频数据源。

package org.loon.framework.game.sound;

import org.loon.framework.game.helper.StreamHelper;
import org.loon.framework.game.net.URI;


public class SoundData ...{

  private byte[] _data;

  private boolean _loop;

  private int _type;

  public static final int _L_SOUNDTYPE_MIDI = 1;

  public static final int _L_SOUNDTYPE_WAV = 2;

  
  public SoundData(URI uri, int type, boolean loop) ...{
    if (uri != null) ...{
      _data = uri.getData();
    }
    _type = type;
    _loop = loop;
  }
  
  
  public SoundData(byte[] data, int type, boolean loop) ...{

    if (data != null && data.length > 0) ...{
      _data = new byte[data.length];
      // 直接copy byte数组
      System.arraycopy(data, 0, _data, 0, _data.length);
    }
    _type = type;
    _loop = loop;
  }
  
  
  public SoundData(String resName, int type, boolean loop) ...{
    this(StreamHelper.GetDataSource(resName),type,loop);
  }

  public byte[] getData() ...{
    return _data;
  }

  public boolean getLoop() ...{
    return _loop;
  }

  public void setLoop(boolean loop) ...{
    _loop = loop;
  }

  public int getType() ...{
    return _type;
  }

}

Loonframework将音频播放相关方法，封装与SoundPlay之中，程序员可以不必理会javax.sound内部细节，而直接调用SoundPlay完成相关操作。

package org.loon.framework.game.sound;

import java.io.ByteArrayInputStream;

import javax.sound.midi.metaEventListener;
import javax.sound.midi.metaMessage;
import javax.sound.midi.MidiSystem;
import javax.sound.midi.Sequence;
import javax.sound.midi.Sequencer;
import javax.sound.sampled.AudioFileFormat;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.Clip;
import javax.sound.sampled.DataLine;

import org.loon.framework.game.net.URI;


public class SoundPlay implements metaEventListener, Runnable ...{

  private int _sleepTime;

  private Clip _audio;

  private Sequencer _midi;

  private boolean _loop;

  private int _soundType;

  private boolean _playing;

  private Thread _thread = null;

  private boolean _isRun = false;

  
  public SoundPlay() ...{

    _loop = false;
    _soundType = 0;
    _sleepTime = 1000;
    _playing = false;

  }

  // 载入声音文件
  public boolean load(SoundData data) ...{
    reset();
    if (data == null || data.getData() == null) ...{
      return false;
    }
    return init(data.getData(), data.getType(), data.getLoop());
  }

  
  public boolean load(URI uri, int ftype, boolean loop) ...{

    // 刷新数据
    reset();
    if (uri == null) ...{
      return false;
    }
    // 获得SoundData
    SoundData data = new SoundData(uri, ftype, loop);
    if (data == null || data.getData() == null) ...{
      return false;
    }
    return init(data.getData(), data.getType(), data.getLoop());

  }

  
  private boolean init(byte[] data, int ftype, boolean loop) ...{
    boolean result = false;

    ByteArrayInputStream bis = null;

    try ...{
      bis = new ByteArrayInputStream(data);
    } catch (Exception e) ...{
      bis = null;
    }

    if (bis == null) ...{
      return false;
    }

    // 判断类型
    switch (ftype) ...{

    // MIDI
    case SoundData._L_SOUNDTYPE_MIDI:

      // 当MIDI不存在时
      if (_midi == null) ...{

 try ...{
   // 获得Sequencer
   _midi = MidiSystem.getSequencer();
   _midi.open();

 } catch (Exception ex) ...{
   _midi = null;
 }

 if (_midi != null) ...{
   _midi.addmetaEventListener(this);
 }

      }

      // 当MIDI依旧未获得时
      if (_midi != null) ...{
 // 重新创建Sequence
 Sequence sc = null;

 try ...{
   sc = MidiSystem.getSequence(bis);
 } catch (Exception e) ...{
   sc = null;
 }

 if (sc != null) ...{

   try ...{

     _midi.setSequence(sc);

     // 获得是否循环播放
     _loop = loop;

     // 获得是否载入
     result = true;

   } catch (Exception ee) ...{
   }

   // 获得声音类型
   _soundType = SoundData._L_SOUNDTYPE_MIDI;

 }

      }

      try ...{
 bis.close();
      } catch (Exception ee) ...{
      }

      break;

    // Wav
    case SoundData._L_SOUNDTYPE_WAV:

      AudioFileFormat type = null;

      // 获得Audio
      try ...{
 type = AudioSystem.getAudioFileFormat(bis);
      } catch (Exception e) ...{
 type = null;
      }

      // 关闭流
      try ...{
 bis.close();
      } catch (Exception ex) ...{
      }

      if (type == null) ...{
 return false;
      }

      // 根据指定信息构造数据行的信息对象
      DataLine.Info di = new DataLine.Info(Clip.class, type.getFormat());

      // 转为Clip
      try ...{
 _audio = (Clip) AudioSystem.getLine(di);
      } catch (Exception e) ...{
      }

      // 播放文件
      try ...{

 _audio.open(type.getFormat(), data, 0, data.length);

 _loop = loop;

 result = true;

      } catch (Exception e) ...{
      }

      // 获得文件类型
      _soundType = SoundData._L_SOUNDTYPE_WAV;

      break;

    }

    return result;
  }

  public boolean play(SoundData data) ...{

    if (!load(data)) ...{
      return false;
    }

    return play();

  }

  public boolean play() ...{

    switch (_soundType) ...{

    case SoundData._L_SOUNDTYPE_MIDI:

      try ...{

 _midi.start();

 _playing = true;

 _soundType = SoundData._L_SOUNDTYPE_MIDI;

      } catch (Exception ee) ...{
      }

      break;

    case SoundData._L_SOUNDTYPE_WAV:

      if (_audio != null) ...{

 if (_loop) ...{

   // 设定循环
   _audio.setLoopPoints(0, -1);
   _audio.setframePosition(0);

   _audio.loop(Clip.LOOP_CONTINUOUSLY);

 } else ...{

   // 强制设定播放位置至0
   _audio.setframePosition(0);

   _audio.start();

 }

 _playing = true;

      }

      break;

    }

    return _playing;

  }

  
  public boolean AutoPlay(SoundData data) ...{
    if (!load(data)) ...{
      return false;
    }
    return AutoPlay();
  }

  
  public boolean AutoPlay() ...{
    _isRun = true;
    _thread = new Thread(this);
    _thread.start();
    return _playing;
  }

  
  public void stop() ...{

    if (_audio != null && _audio.isActive()) ...{
      try ...{
 _audio.stop();
      } catch (Exception e) ...{
      }
    }

    if (_midi != null) ...{
      _midi.stop();
    }
    _playing = false;
    _isRun = false;
  }

  
  public void reset() ...{

    stop();

    _loop = false;
    _soundType = 0;

    if (_midi != null) ...{

      _midi.close();

      _midi = null;

    }

    if (_audio != null && _audio.isOpen()) ...{

      _audio.close();

      _audio = null;

    }
    _isRun = false;
    _thread = null;
  }

  
  public void meta(metaMessage meta) ...{
    // 判断是否循环播放MIDI
    if (_loop && _soundType == SoundData._L_SOUNDTYPE_MIDI
 && meta.getType() == 47) ...{

      if (_midi != null && _midi.isOpen()) ...{
 _midi.setMicrosecondPosition(0);
 _midi.start();

      }
    }

  }

  public void run() ...{
    while (_isRun) ...{
      play();
      // 因为播放类型唯一，所以只会返回一个_playing结果,以此判定。
      if (_midi != null) ...{
 _playing = _midi.isRunning();
      }
      if (_audio != null) ...{
 _playing = _audio.isRunning();
      }
      // 当播放停止
      if (!_playing) ...{
 // 释放
 reset();
      }
      try ...{
 Thread.sleep(_sleepTime);
      } catch (InterruptedException e) ...{
 e.printStackTrace();
      }
    }
  }

  public int getSleepTime() ...{
    return _sleepTime;
  }

  
  public void setSleepTime(int time) ...{
    _sleepTime = time;
  }
}

这时我们需要面对的，仅是封装为实体的SoundData数据和SoundPlay操作，而不必和繁复的javax.sound再打交道。

调用方法如下：

package org.test;

import org.loon.framework.game.helper.StreamHelper;
import org.loon.framework.game.net.URI;
import org.loon.framework.game.sound.SoundData;
import org.loon.framework.game.sound.SoundPlay;


public class SoundPlayTest ...{

  static void selectPlay(int ftype)...{
    SoundData data=null;
    
    switch(ftype)...{
    //通过loonframework下uri从网络播放音乐
    case 0:
      data=new SoundData(new URI("http://looframework.sourceforge.net/midi/谁是大英雄.mid"),SoundData._L_SOUNDTYPE_MIDI,false);
      break;
    //通过本地资源下音乐文件的byte[]对象播放音乐
    case 1:
      byte[] bytes=StreamHelper.GetResourceData("/midi/谁是大英雄.mid");
      data=new SoundData(bytes,SoundData._L_SOUNDTYPE_MIDI,false);
      break;
      //通过音乐文件路径播放音乐  
    case 2:
      data=new SoundData("C:/谁是大英雄.mid",SoundData._L_SOUNDTYPE_MIDI,false);
      break;
    }
    SoundPlay play=new SoundPlay();
    //AutoPlay与Play方法的区别在于,AutoPlay播放完毕会自动停止并释放资源，play需手动中止。
    //play.play(data);
    play.AutoPlay(data);
  }
  
  public static void main(String[]args)...{
    selectPlay(2);
  }
  
}

更详细方法，会待Loonframework-game完全公布后，再进行解释。

另：由于StreamHelper关联其他Loonframework中方法，暂不给出，inputStream转byte[]可用如下写法：

//is为获得的inputStream

  ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
//用于承接byte[]
    byte[] arrayByte = null;
    try ...{
      // 每次传输大小为4096
      byte[] bytes = new byte[4096];
      bytes = new byte[is.available()];
      int read;
      while ((read = is.read(bytes)) >= 0) ...{
 byteArrayOutputStream.write(bytes, 0, read);
      }
      arrayByte = byteArrayOutputStream.toByteArray();
    } catch (IOException e) ...{
      return null;
    } finally ...{
      try ...{
 if (byteArrayOutputStream != null) ...{
   byteArrayOutputStream.close();
   byteArrayOutputStream = null;
 }
 if (is != null) ...{
   is.close();
   is = null;
 }

      } catch (IOException e) ...{
      }
    }