Java Sound, Getting Started I

資料來源 : Java Sound, Getting Started, Part 1, Playback

 

== 前言 ==

This is the second lesson in a series of lessons designed to teach you how to use the Java Sound API.  The first lesson in the series was entitled Java Sound, An Introduction.

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What's Next?

In this lesson, I explained that the Java Sound API is based on the concept of mixers and lines.  However, the audio output code that I explained didn't obviously involve mixers.  The AudioSystem class provides static methods that make it possible to write audio programs without having to deal directly with mixers.  In other words, the static methods abstract mixers into the background.

In the next lesson, I will explain the audio capture code in a slightly modified version of the program that was discussed in this lesson.  The modified version will make explicit use of mixers in order to show you how you can use them when you need to use them.

Complete Program Listing

A complete listing of the program is shown in Listing 11.

/*File AudioCapture01.java

This program demonstrates the capture

and subsequent playback of audio data.

A GUI appears on the screen containing

the following buttons:

Capture

Stop

Playback

Input data from a microphone is

captured and saved in a

ByteArrayOutputStream object when the

user clicks the Capture button.

Data capture stops when the user clicks

the Stop button.

Playback begins when the user clicks

the Playback button.

Tested using SDK 1.4.0 under Win2000

**************************************/

import javax.swing.*;

import java.awt.*;

import java.awt.event.*;

import java.io.*;

import javax.sound.sampled.*;

public class AudioCapture01

                        extends JFrame{

  boolean stopCapture = false;

  ByteArrayOutputStream

                 byteArrayOutputStream;

  AudioFormat audioFormat;

  TargetDataLine targetDataLine;

  AudioInputStream audioInputStream;

  SourceDataLine sourceDataLine;

  public static void main(

                        String args[]){

    new AudioCapture01();

  }//end main

  public AudioCapture01(){//constructor

    final JButton captureBtn =

                new JButton("Capture");

    final JButton stopBtn =

                   new JButton("Stop");

    final JButton playBtn =

               new JButton("Playback");

    captureBtn.setEnabled(true);

    stopBtn.setEnabled(false);

    playBtn.setEnabled(false);

    //Register anonymous listeners

    captureBtn.addActionListener(

      new ActionListener(){

        public void actionPerformed(

                        ActionEvent e){

          captureBtn.setEnabled(false);

          stopBtn.setEnabled(true);

          playBtn.setEnabled(false);

          //Capture input data from the

          // microphone until the Stop

          // button is clicked.

          captureAudio();

        }//end actionPerformed

      }//end ActionListener

    );//end addActionListener()

    getContentPane().add(captureBtn);

    stopBtn.addActionListener(

      new ActionListener(){

        public void actionPerformed(

                        ActionEvent e){

          captureBtn.setEnabled(true);

          stopBtn.setEnabled(false);

          playBtn.setEnabled(true);

          //Terminate the capturing of

          // input data from the

          // microphone.

          stopCapture = true;

        }//end actionPerformed

      }//end ActionListener

    );//end addActionListener()

    getContentPane().add(stopBtn);

    playBtn.addActionListener(

      new ActionListener(){

        public void actionPerformed(

                        ActionEvent e){

          //Play back all of the data

          // that was saved during

          // capture.

          playAudio();

        }//end actionPerformed

      }//end ActionListener

    );//end addActionListener()

    getContentPane().add(playBtn);

    getContentPane().setLayout(

                     new FlowLayout());

    setTitle("Capture/Playback Demo");

    setDefaultCloseOperation(

                        EXIT_ON_CLOSE);

    setSize(250,70);

    setVisible(true);

  }//end constructor

  //This method captures audio input

  // from a microphone and saves it in

  // a ByteArrayOutputStream object.

  private void captureAudio(){

    try{

      //Get everything set up for

      // capture

      audioFormat = getAudioFormat();

      DataLine.Info dataLineInfo =

                new DataLine.Info(

                  TargetDataLine.class,

                   audioFormat);

      targetDataLine = (TargetDataLine)

                   AudioSystem.getLine(

                         dataLineInfo);

      targetDataLine.open(audioFormat);

      targetDataLine.start();

      //Create a thread to capture the

      // microphone data and start it

      // running.  It will run until

      // the Stop button is clicked.

      Thread captureThread =

                new Thread(

                  new CaptureThread());

      captureThread.start();

    } catch (Exception e) {

      System.out.println(e);

      System.exit(0);

    }//end catch

  }//end captureAudio method

  //This method plays back the audio

  // data that has been saved in the

  // ByteArrayOutputStream

  private void playAudio() {

    try{

      //Get everything set up for

      // playback.

      //Get the previously-saved data

      // into a byte array object.

      byte audioData[] =

                 byteArrayOutputStream.

                         toByteArray();

      //Get an input stream on the

      // byte array containing the data

      InputStream byteArrayInputStream

            = new ByteArrayInputStream(

                            audioData);

      AudioFormat audioFormat =

                      getAudioFormat();

      audioInputStream =

        new AudioInputStream(

          byteArrayInputStream,

          audioFormat,

          audioData.length/audioFormat.

                       getFrameSize());

      DataLine.Info dataLineInfo =

                new DataLine.Info(

                  SourceDataLine.class,

                          audioFormat);

      sourceDataLine = (SourceDataLine)

                   AudioSystem.getLine(

                         dataLineInfo);

      sourceDataLine.open(audioFormat);

      sourceDataLine.start();

      //Create a thread to play back

      // the data and start it

      // running.  It will run until

      // all the data has been played

      // back.

      Thread playThread =

          new Thread(new PlayThread());

      playThread.start();

    } catch (Exception e) {

      System.out.println(e);

      System.exit(0);

    }//end catch

  }//end playAudio

  //This method creates and returns an

  // AudioFormat object for a given set

  // of format parameters.  If these

  // parameters don't work well for

  // you, try some of the other

  // allowable parameter values, which

  // are shown in comments following

  // the declarations.

  private AudioFormat getAudioFormat(){

    float sampleRate = 8000.0F;

    //8000,11025,16000,22050,44100

    int sampleSizeInBits = 16;

    //8,16

    int channels = 1;

    //1,2

    boolean signed = true;

    //true,false

    boolean bigEndian = false;

    //true,false

    return new AudioFormat(

                      sampleRate,

                      sampleSizeInBits,

                      channels,

                      signed,

                      bigEndian);

  }//end getAudioFormat

//===================================//

//Inner class to capture data from

// microphone

class CaptureThread extends Thread{

  //An arbitrary-size temporary holding

  // buffer

  byte tempBuffer[] = new byte[10000];

  public void run(){

    byteArrayOutputStream =

           new ByteArrayOutputStream();

    stopCapture = false;

    try{//Loop until stopCapture is set

        // by another thread that

        // services the Stop button.

      while(!stopCapture){

        //Read data from the internal

        // buffer of the data line.

        int cnt = targetDataLine.read(

                    tempBuffer,

                    0,

                    tempBuffer.length);

        if(cnt > 0){

          //Save data in output stream

          // object.

          byteArrayOutputStream.write(

                   tempBuffer, 0, cnt);

        }//end if

      }//end while

      byteArrayOutputStream.close();

    }catch (Exception e) {

      System.out.println(e);

      System.exit(0);

    }//end catch

  }//end run

}//end inner class CaptureThread

//===================================//

//Inner class to play back the data

// that was saved.

class PlayThread extends Thread{

  byte tempBuffer[] = new byte[10000];

  public void run(){

    try{

      int cnt;

      //Keep looping until the input

      // read method returns -1 for

      // empty stream.

      while((cnt = audioInputStream.

        read(tempBuffer, 0,

            tempBuffer.length)) != -1){

        if(cnt > 0){

          //Write data to the internal

          // buffer of the data line

          // where it will be delivered

          // to the speaker.

          sourceDataLine.write(

                   tempBuffer, 0, cnt);

        }//end if

      }//end while

      //Block and wait for internal

      // buffer of the data line to

      // empty.

      sourceDataLine.drain();

      sourceDataLine.close();

    }catch (Exception e) {

      System.out.println(e);

      System.exit(0);

    }//end catch

  }//end run

}//end inner class PlayThread

//===================================//

}//end outer class AudioCapture01.java