通过J2ME的录音功能实现简易示波器


		早就有人通过PC声卡的输入(麦克风孔)来做模拟示波器，但是用手机来实现的比较少。用J2ME的MMAPI实现模拟示波器，具体效果稍逊于智能机，因为智能机可以实时读取麦克风输入流，而J2ME还需要有短暂的缓冲构成了阻塞，不过，实现出来玩一下还是足够了。
先贴出效果图：
 
左图是程序在WTK

运行的结果，右图是Audition读取音频输入口的波形，信号源是一个经过信号放大的压力传感器。
程序使用NetBeans + LWUIT类库，接下来贴出全部代码：
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import com.sun.lwuit.Command;   
import com.sun.lwuit.Display;   
import com.sun.lwuit.Form;   
import com.sun.lwuit.events.ActionEvent;   
import com.sun.lwuit.events.ActionListener;   
import com.sun.lwuit.layouts.BorderLayout;   
import java.io.ByteArrayOutputStream;   
import javax.microedition.media.Manager;   
import javax.microedition.media.Player;   
import javax.microedition.media.control.RecordControl;   
  
/**  
 * @author 张国威  
 */  
public class Frm_MainMenu extends javax.microedition.midlet.MIDlet implements ActionListener {   
    public Form form ;   
    private  Command cmdExit = new Command("退出", 1);   
    private ThreadReceive threadReceive =new ThreadReceive();//接收数据线程   
    private Cmp_Wave cmp_HeartWave=null;   
    private Player capturePlayer = null;   
    private RecordControl recordControl = null;   
    private ByteArrayOutputStream bos = new ByteArrayOutputStream();   
    public void startApp() {   
        Display.init(this);   
           
        form = new Form();//达到全屏的效果   
        cmp_HeartWave=new Cmp_Wave(form.getHeight(),form.getWidth());   
        form.getStyle().setBgImage(null);//本窗体不需要背景   
        form.addCommand(cmdExit);   
        form.setCommandListener(this);   
        form.setLayout(new BorderLayout());   
        //设置画板控件   
        form.addComponent(BorderLayout.CENTER,cmp_HeartWave);//添加控件   
        form.show();   
        try {   
          capturePlayer = Manager.createPlayer("capture://audio?rate=8000&bits=8&channels=1");//PCM，8位，8kH   
          if (capturePlayer != null) {   
            capturePlayer.realize();   
            recordControl = (RecordControl) capturePlayer   
                .getControl("javax.microedition.media.control.RecordControl");   
            if (recordControl == null)   
              throw new Exception("No RecordControl available");   
            recordControl.setRecordStream(bos);   
          } else {   
            throw new Exception("Capture Audio Player is not available");   
          }   
        } catch (Exception e) {}   
        threadReceive.start();//开始启动线程   
  }   
/*  
 * byte转为int的函数，因为JAVA的byte范围从-127~127  
 */  
public static int unsignedByteToInt(byte b) {   
    return (int) b & 0xFF;   
    }   
class ThreadReceive extends Thread {   
      private boolean isRuning=true;//默认线程内部while循环可以执行   
      public void StopThread()   
      {   
          isRuning=false;   
      }   
      public void run(){   
          //*************************************************************   
          //绘制波形数据   
          //*************************************************************   
          try {   
              capturePlayer.start();   
              while(isRuning)   
              {   
                  recordControl = (RecordControl) capturePlayer.getControl("javax.microedition.media.control.RecordControl");   
                  recordControl.setRecordStream(bos);   
                  recordControl.startRecord();   
                  Thread.sleep(25);//停顿25ms录音   
                  recordControl.stopRecord();   
                  recordControl.commit();   
                  //由于采集频率太高，手机不能完全显示，所以需要通过均值滤波来降低分辨率   
                  int Zoom_out=200;//缩小200倍   
                  int[] bits=new int[bos.toByteArray().length/Zoom_out];   
                  for(int i=0,total=0,index=0;i<bos.toByteArray().length;i++)

补充：移动开发 , Android ,