通過J2ME的錄音功能實現簡易示波器

本文來自http://blog.csdn.net/hellogv/ ，引用必須註明出處！

早就有人通過PC聲卡的輸入(麥克風孔)來做模擬示波器，但是用手機來實現的比較少。用J2ME的MMAPI實現模擬示波器，具體效果稍遜於智能機，因爲智能機可以實時讀取麥克風輸入流，而J2ME還需要有短暫的緩衝構成了阻塞，不過，實現出來玩一下還是足夠了。

先貼出效果圖：

左圖是程序在WTK運行的結果，右圖是Audition讀取音頻輸入口的波形，信號源是一個經過信號放大的壓力傳感器。

程序使用NetBeans + LWUIT類庫，接下來貼出全部代碼：

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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 張國威
*/
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();//接收數據線程
    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();//達到全屏的效果
        cmp_HeartWave=new Cmp_Wave(form.getHeight(),form.getWidth());
        form.getStyle().setBgImage(null);//本窗體不需要背景
        form.addCommand(cmdExit);
        form.setCommandListener(this);
        form.setLayout(new BorderLayout());
        //設置畫板控件
        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();//開始啓動線程
}
/*
* byte轉爲int的函數，因爲JAVA的byte範圍從-127~127
*/
public static int unsignedByteToInt(byte b) {
    return (int) b & 0xFF;
    }
class ThreadReceive extends Thread {
      private boolean isRuning=true;//默認線程內部while循環可以執行
      public void StopThread()
      {
          isRuning=false;
      }
      public void run(){
          //*************************************************************
          //繪製波形數據
          //*************************************************************
          try {
              capturePlayer.start();
              while(isRuning)
              {
                  recordControl = (RecordControl) capturePlayer.getControl("javax.microedition.media.control.RecordControl");
                  recordControl.setRecordStream(bos);
                  recordControl.startRecord();
                  Thread.sleep(25);//停頓25ms錄音
                  recordControl.stopRecord();
                  recordControl.commit();
                  //由於採集頻率太高，手機不能完全顯示，所以需要通過均值濾波來降低分辨率
                  int Zoom_out=200;//縮小200倍
                  int[] bits=new int[bos.toByteArray().length/Zoom_out];
                  for(int i=0,total=0,index=0;i<bos.toByteArray().length;i++)
                  {
                      total=total+unsignedByteToInt(bos.toByteArray()[i]);
                      if(i%Zoom_out==0 && i!=0)
                      {
                          bits[index]=total/Zoom_out;
                          total=0;
                          index++;
                      }
                  }
                  cmp_HeartWave.UpdateVerticalWave(bits);
                  bos.reset();
              }
              capturePlayer.stop();
              capturePlayer.close();
          } catch (Exception e) {}
      }
}
    public void actionPerformed(ActionEvent arg0) {
        Command command=arg0.getCommand();
        if(command==cmdExit)//退出程序
            notifyDestroyed();
    }
    protected void pauseApp() {}
    protected void destroyApp(boolean arg0) {}

}
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 張國威
*/
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();//接收數據線程
    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();//達到全屏的效果
        cmp_HeartWave=new Cmp_Wave(form.getHeight(),form.getWidth());
        form.getStyle().setBgImage(null);//本窗體不需要背景
        form.addCommand(cmdExit);
        form.setCommandListener(this);
        form.setLayout(new BorderLayout());
        //設置畫板控件
        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();//開始啓動線程
}
/*
* byte轉爲int的函數，因爲JAVA的byte範圍從-127~127
*/
public static int unsignedByteToInt(byte b) {
    return (int) b & 0xFF;
    }
class ThreadReceive extends Thread {
      private boolean isRuning=true;//默認線程內部while循環可以執行
      public void StopThread()
      {
          isRuning=false;
      }
      public void run(){
          //*************************************************************
          //繪製波形數據
          //*************************************************************
          try {
              capturePlayer.start();
              while(isRuning)
              {
                  recordControl = (RecordControl) capturePlayer.getControl("javax.microedition.media.control.RecordControl");
                  recordControl.setRecordStream(bos);
                  recordControl.startRecord();
                  Thread.sleep(25);//停頓25ms錄音
                  recordControl.stopRecord();
                  recordControl.commit();
                  //由於採集頻率太高，手機不能完全顯示，所以需要通過均值濾波來降低分辨率
                  int Zoom_out=200;//縮小200倍
                  int[] bits=new int[bos.toByteArray().length/Zoom_out];
                  for(int i=0,total=0,index=0;i<bos.toByteArray().length;i++)
                  {
                      total=total+unsignedByteToInt(bos.toByteArray()[i]);
                      if(i%Zoom_out==0 && i!=0)
                      {
                          bits[index]=total/Zoom_out;
                          total=0;
                          index++;
                      }
                  }
                  cmp_HeartWave.UpdateVerticalWave(bits);
                  bos.reset();
              }
              capturePlayer.stop();
              capturePlayer.close();
          } catch (Exception e) {}
      }
}
    public void actionPerformed(ActionEvent arg0) {
        Command command=arg0.getCommand();
        if(command==cmdExit)//退出程序
            notifyDestroyed();
    }
    protected void pauseApp() {}
    protected void destroyApp(boolean arg0) {}

}

以下代碼爲畫波形圖的代碼：

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/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
import com.sun.lwuit.Component;
import com.sun.lwuit.Container;
import com.sun.lwuit.Graphics;
import com.sun.lwuit.Image;
import com.sun.lwuit.layouts.BorderLayout;
/**
*
* @author Administrator
*/
public class Cmp_Wave extends Container{
   private Image imgWaveCanvas;//波形圖畫板，圖形畫在圖像上，再不斷地貼圖到屏幕
   private int height; //自己定義的畫板高度 getHeight()
   private int width; //自己定義的畫板寬度 getWidth()
   private int old_xPos=-1;//位置初始化
   private int old_yPos=-1;//位置初始化
   private Component cmpWaveCanvas;//顯示波形控件
   private int[] point=null;//每次收到的point數組
   public Cmp_Wave(int canvasHeight,int canvasWidth)
   {
       super.setLayout(new BorderLayout());
       super.addComponent(BorderLayout.CENTER,WaveCanvas(canvasHeight,canvasWidth));//波形顯示在中間
   }
   private Component WaveCanvas(int canvasHeight,int canvasWidth)
{
      height=canvasHeight;
      width=canvasWidth;
      //-------初始化波形畫板圖像
      imgWaveCanvas=Image.createImage(width, height);
      //-------初始化波形畫板控件，在控件上繪製波形畫板圖像
      cmpWaveCanvas=new Component(){
            public void paint(Graphics g) {
                //在內存中繪製波形圖
                Graphics canvas=imgWaveCanvas.getGraphics();

                if(point==null)//如果point還沒初始化
                    return;//不執行下面語句
                for(int i=0;i<point.length;i++)
                {
                    if(old_xPos>=width //如果xPos超過屏幕寬度
                    || old_xPos==-1) //如果PaintVerticalWave是第一次運行
                    {
                        old_xPos=0;//歸零畫圖
                        old_yPos=height/2;//中心點畫圖
                        canvas.setColor(0x444444);//設置背景色
                        canvas.fillRect(0, 0, width, height);
                    }
                    int new_yPosPoint=point[i] ;
                    canvas.setColor(0xCCCCCC);//線條色
                    canvas.drawLine(old_xPos,old_yPos,old_xPos+1,new_yPosPoint);
                    old_xPos++;
                    old_yPos=new_yPosPoint;
                }
                //把內存中的波形圖畫到控件上
                g.drawImage(imgWaveCanvas, 0, 0);
            }
      };
      cmpWaveCanvas.setFocusPainted(false);
      cmpWaveCanvas.setFocusable(false);
      return cmpWaveCanvas;
}
   public void UpdateVerticalWave(int []yPos) {
       //更新繪圖數組
       int []tmpPos=new int[yPos.length];//臨時數組，只取原數組的waveN分之一
       for(int i=0,ii=0;i<tmpPos.length;i++,ii+=1)
           tmpPos[i]=yPos[ii];
       point=tmpPos;
       //重新繪圖
       cmpWaveCanvas.repaint();
   }
}