Java Sound, Getting Started II

資料來源 : Java Sound, Getting Started, Part 2, Playback

== 前言 ==

This series of lessons is designed to teach you how to use the Java Sound API. 

The first lesson in the series was entitled Java Sound, An Introduction. 

The previous lesson was entitled Java Sound, Getting Started, Part 1, Playback. 

This lesson, entitled Java Sound, Getting Started, Part 2, Capture using Specified Mixer, is a follow-on to the previous lesson.

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Summary

In this lesson, I showed you how to use the Java Sound API to capture audio data from a microphone and how to save that data in a ByteArrayOutputStream object.  I also showed you how to identify the mixers available on your system, and how to specify a particular mixer for use in the acquisition of audio data from the microphone.

Complete Program Listing

A complete listing of the program is shown in Listing 12.

/*File AudioCapture02.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.

This version of the program gets and  displays a

list of available mixers, producing the following

output:

Available mixers:

Java Sound Audio Engine

Microsoft Sound Mapper

Modem #0 Line Record

ESS Maestro

Thus, this machine had the four mixers listed 

above available at the time the program was run.

Then the program gets and uses one of the 

available mixers instead of simply asking for a 

compatible mixer as was the case in a previous 

version of the program.

Either of the following two mixers can be used in

this program:

Microsoft Sound Mapper

ESS Maestro

Neither of the following two mixers will work in

this program.  The mixers fail at runtime for 

different reasons:

Java Sound Audio Engine

Modem #0 Line Record

The Java Sound Audio Engine mixer fails due to a 

data format compatibility problem.

The Modem #0 Line Record mixer fails due to an 

"Unexpected Error"

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 AudioCapture02 extends JFrame{

  boolean stopCapture = false;

  ByteArrayOutputStream byteArrayOutputStream;

  AudioFormat audioFormat;

  TargetDataLine targetDataLine;

  AudioInputStream audioInputStream;

  SourceDataLine sourceDataLine;

  public static void main(String args[]){

    new AudioCapture02();

  }//end main

  public AudioCapture02(){//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 and display a list of

      // available mixers.

      Mixer.Info[] mixerInfo = 

                      AudioSystem.getMixerInfo();

      System.out.println("Available mixers:");

      for(int cnt = 0; cnt < mixerInfo.length;

                                          cnt++){

          System.out.println(mixerInfo[cnt].

                                        getName());

      }//end for loop

      //Get everything set up for capture

      audioFormat = getAudioFormat();

      DataLine.Info dataLineInfo =

                            new DataLine.Info(

                            TargetDataLine.class,

                            audioFormat);

      //Select one of the available

      // mixers.

      Mixer mixer = AudioSystem.

                          getMixer(mixerInfo[3]);

      //Get a TargetDataLine on the selected

      // mixer.

      targetDataLine = (TargetDataLine)

                     mixer.getLine(dataLineInfo);

      //Prepare the line for use.

      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 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 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 declartions.

  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 AudioCapture02.java