熟练使用J2ME可选包MMAPI

核心提示： 了解J2ME可选包MMAPI一文向读者介绍了MMAPI的基本知识，掌握MMAPI的灵活性应该是重点，熟练使用J2ME可选包MMAPI，本文将讲述如何在实际开发中使用MMAPI， 本文的目的是为读者提供处理不同情况的代码，您可以参考MMAPI DOC，播放单音try { Manager.playTone(Tone

　  了解J2ME可选包MMAPI一文向读者介绍了MMAPI的基本知识，掌握MMAPI的灵活性应该是重点。本文将讲述如何在实际开发中使用MMAPI。

　  本文的目的是为读者提供处理不同情况的代码，您可以参考MMAPI DOC。

1. 播放单音
   try {
   　  Manager.playTone(ToneControl.C4, 5000 /* millisec */, 100 /* max vol */);
   } catch (MediaException e) { }
   
2. 简单媒体重放功能实现
   try {
   　  Player p = Manager.createPlayer("http://webserver/music.mp3");
   　  p.setLoopCount(5);
   　  p.start();
   } catch (IOException ioe) {
   } catch (MediaException me) { }
   
3. 详细重放控制
   static final long SECS_TO_MICROSECS = 1000000L;
   Player p;
   VolumeControl vc;
   try {
   　  p = Manager.createPlayer("http://webserver/music.mp3");
   　  p.realize();
   　 // Set a listener.
   　 p.addPlayerListener(new Listener());
   　 // Grab volume control for the player.
   　 // Set Volume to max.
   　 vc = (VolumeControl)p.getControl("VolumeControl");
   　 if (vc != null)
   　　  vc.setLevel(100);
   　 // Set a start time.
   　 p.setMediaTime(5 * SECS_TO_MICROSECS);
   　 // Guarantee that the player can start with the smallest latency.
   　 p.PRefetch();
   　 // Non-blocking start
   　 p.start();
   } catch (IOException ioe) {
   } catch (MediaException me) { }
   class Listener implements PlayerListener {
   　  public void playerUpdate(Player p, String event, Object eventData) {
   　　　  if (event == END_OF_MEDIA event == STOP_AT_TIME) {
   　　　　　  System.out.println("Done processing");
   　　　　　  try {
   　　　　　　　  p.setMediaTime(5 * SECS_TO_MICROSECS);
   　　　　　　　  p.start();
   　　　　　  } catch (MediaException me) { }
   　　　　　  break;
   　　　  }
   　  }
   }
   
4. 实现MIDI重放控制
   

   Player p;
   TempoControl tc;
   
   try {
       p = Manager.createPlayer("http://webserver/tune.mid");
       p.realize();
   
       // Grab the tempo control.
       tc = (TempoControl)p.getControl("TempoControl");
       tc.setTempo(120000); // 120 beats/min
       p.start();
   
   } catch (IOException ioe) {
   } catch (MediaException me) { }
   

5. 视频重放功能实现
   

   Player p;
   
         
         
   VideoControl vc;
   
   try {
       p = Manager.createPlayer("http://webserver/movie.mpg");
       p.realize();
   
       // Grab the video control and set it to the current display.
       vc = (VideoControl)p.getControl("VideoControl");
       if (vc != null) {
           Form form = new Form("video");
           form.append((Item)vc.initDisplayMode(vc.USE_GUI_PRIMITIVE, null));
           Display.getDisplay(midlet).setCurrent(form);
       }
   
       p.start();
   
   } catch (IOException ioe) {
   } catch (MediaException me) { }
   

6. 播放RMS内存储的数据
   

   RecordStore rs;
   int recordID;
      :  // code to set up the record store.
   
   try {
       InputStream is = new
       ByteArrayInputStream(rs.getRecord(recordID));
       Player p = Manager.createPlayer(is, "audio/X-wav");
       p.start();
   } catch (IOException ioe) {
   } catch (MediaException me) { }
   

7. 播放Jar文件中存储的媒体
   

   /** Notice that in MIDP 2.0, the wav format is mandatory only */
   /** in the case that the device supports sampled audio.       */
   
   try {
       InputStream is = getClass().getResourceAsStream("audio.wav");
       Player p = Manager.createPlayer(is, "audio/X-wav");
       p.start();
   } catch (IOException ioe) {
   } catch (MediaException me) { }
   

8. 不同Player的同步
   

   Player p1, p2;
   
   try {
       p1 = Manager.createPlayer("http://webserver/tune.mid");
       p1.realize();
       p2 = Manager.createPlayer("http://webserver/movie.mpg");
       p2.realize();
       p2.setTimeBase(p1.getTimeBase());
       p1.prefetch();
       p2.prefetch();
       p1.start();
       p2.start();
   } catch (IOException ioe) {
   } catch (MediaException me) { }
   

9. 产生单音序列
   byte tempo = 30; // set tempo to 120 bpm
   byte d = 8;　　  // eighth-note
   
   byte C4 = ToneControl.C4;;
   byte D4 = (byte)(C4 + 2); // a whole step
   byte E4 = (byte)(C4 + 4); // a major third
   byte G4 = (byte)(C4 + 7); // a fifth
   byte rest = ToneControl.SILENCE; // rest
   
   byte[] mySequence = {
   　  ToneControl.VERSION, 1,　 // version 1
   　  ToneControl.TEMPO, tempo, // set tempo
   　  ToneControl.BLOCK_START, 0,　 // start define "A" section
   　  E4,d, D4,d, C4,d, E4,d,　　　 // content of "A" section
   　  E4,d, E4,d, E4,d, rest,d,　　　　　
   　  ToneControl.BLOCK_END, 0,　　 // end define "A" section
   　  ToneControl.PLAY_BLOCK, 0,　  // play "A" section
   　  D4,d, D4,d, D4,d, rest,d,　　 // play "B" section
   　  E4,d, G4,d, G4,d, rest,d,
   　  ToneControl.PLAY_BLOCK, 0,　  // repeat "A" section
   　  D4,d, D4,d, E4,d, D4,d, C4,d  // play "C" section
   };
   
   try{
   　  Player p = Manager.createPlayer(Manager.TONE_DEVICE_LOCATOR);
   　  p.realize();
   　  ToneControl c = (ToneControl)p.getControl("ToneControl");
   　  c.setSequence(mySequence);
   　  p.start();
   } catch (IOException ioe) {
   } catch (MediaException me) { }
   
10. 语音捕获和录音功能的实现
    

    try {
        // Create a DataSource that captures live audio.
        Player p = Manager.createPlayer("capture://audio");
        p.realize();
        // Get the RecordControl, set the record location, and 
        // start the Player and record for 5 seconds.
        RecordControl rc = (RecordControl)p.getControl("RecordControl");
        rc.setRecordLocation("file:/tmp/audio.wav");
        rc.startRecord();
        p.start();
        Thread.currentThread().sleep(5000);
        p.stop();
        rc.stopRecord();
        rc.commit();
    } catch (IOException ioe) {
    } catch (MediaException me) {
    } catch (InterruptedException e) { }
    

11. 实现摄像功能
    Player p;
    VideoControl vc;
    
    // initialize camera 
    try {
        p = Manager.createPlayer("capture://video");
        p.realize();
    
        // Grab the video control and set it to the current display.
        vc = (VideoControl)p.getControl("VideoControl");
        if (vc != null) {
            Form form = new Form("video");
            form.append((Item)vc.initDisplayMode(vc.USE_GUI_PRIMITIVE, null));
            Display.getDisplay(midlet).setCurrent(form);
        }
    
        p.start();
    
    } catch (IOException ioe) {
    } catch (MediaException me) { }
    
    // now take a picture
    try {
        byte[] pngImage = vc.getSnapshot(null);
    
        // do something with the image ...
    } catch (MediaException me) { }
    
    
    在后面的文章中我们将通过完整的实例演示如何使用MMAPI开发应用程序。　 

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