Java类作为应用程序工作，但不作为applet工作

Question

I am an android developer and do not have extensive knowledge about java web development, so please bear with me if the question is a little weird. I have created a java class which is supposed to receive data packets in form of audio from an android app and plays it on PC speakers. The application is basically a streaming app from phone to server. The class is running fine as an application.

Here is the code for the class :

class Server {

AudioInputStream audioInputStream;
static AudioInputStream ais;
static AudioFormat format;
static boolean status = true;
static int port = 50005;
static int sampleRate = 8000;



public static void main(String args[]) throws Exception {


    DatagramSocket serverSocket = new DatagramSocket(50005);

    /**
     * Formula for lag = (byte_size/sample_rate)*2
     * Byte size 9728 will produce ~ 0.45 seconds of lag. Voice slightly broken.
     * Byte size 1400 will produce ~ 0.06 seconds of lag. Voice extremely broken.
     * Byte size 4000 will produce ~ 0.18 seconds of lag. Voice slightly more broken then 9728.
     */

    byte[] receiveData = new byte[5000];

    format = new AudioFormat(sampleRate, 16, 1, true, false);

    while (status == true) {
        DatagramPacket receivePacket = new DatagramPacket(receiveData,
                receiveData.length);

        serverSocket.receive(receivePacket);

        ByteArrayInputStream baiss = new ByteArrayInputStream(
                receivePacket.getData());

        ais = new AudioInputStream(baiss, format, receivePacket.getLength());
        toSpeaker(receivePacket.getData());

    }



}

public static void toSpeaker(byte soundbytes[]) {
    try {

        DataLine.Info dataLineInfo = new DataLine.Info(SourceDataLine.class, format);
        SourceDataLine sourceDataLine = (SourceDataLine) AudioSystem.getLine(dataLineInfo);

        sourceDataLine.open(format);

        FloatControl volumeControl = (FloatControl) sourceDataLine.getControl(FloatControl.Type.MASTER_GAIN);
        volumeControl.setValue(6.0206f);

        sourceDataLine.start();
        sourceDataLine.open(format);

        sourceDataLine.start();

        System.out.println("format? :" + sourceDataLine.getFormat());

        sourceDataLine.write(soundbytes, 0, soundbytes.length);
        System.out.println(soundbytes.toString());
        sourceDataLine.drain();
        sourceDataLine.close();
    } catch (Exception e) {
        System.out.println("Not working in speakers...");
        e.printStackTrace();
    }
}
}

Now I wanted to convert the class into an applet such that I can deploy the same as a web application. Here is the code for the applet :

public class AppletTest extends Applet {


    AudioInputStream audioInputStream;
    static AudioInputStream ais;
    static AudioFormat format;
    static boolean status = true;
    static int port = 50005;
    static int sampleRate = 8000;



    public void init()
    {

    }

    public void stop()
    {

    }



    public void listening()
    {
         DatagramSocket serverSocket = null;
        try {
            serverSocket = new DatagramSocket(50005);
        } catch (SocketException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

            /**
             * Formula for lag = (byte_size/sample_rate)*2
             * Byte size 9728 will produce ~ 0.45 seconds of lag. Voice slightly broken.
             * Byte size 1400 will produce ~ 0.06 seconds of lag. Voice extremely broken.
             * Byte size 4000 will produce ~ 0.18 seconds of lag. Voice slightly more broken then 9728.
             */

            byte[] receiveData = new byte[5000];

            format = new AudioFormat(sampleRate, 16, 1, true, false);

            while (status == true) {
                DatagramPacket receivePacket = new DatagramPacket(receiveData,
                        receiveData.length);

                try {
                    serverSocket.receive(receivePacket);
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

                ByteArrayInputStream baiss = new ByteArrayInputStream(
                        receivePacket.getData());

                ais = new AudioInputStream(baiss, format, receivePacket.getLength());
                toSpeaker(receivePacket.getData());

            }
    }



    public static void toSpeaker(byte soundbytes[]) {
        try {

            DataLine.Info dataLineInfo = new DataLine.Info(SourceDataLine.class, format);
            SourceDataLine sourceDataLine = (SourceDataLine) AudioSystem.getLine(dataLineInfo);

            sourceDataLine.open(format);

            FloatControl volumeControl = (FloatControl) sourceDataLine.getControl(FloatControl.Type.MASTER_GAIN);
            volumeControl.setValue(6.0206f);

            sourceDataLine.start();
            sourceDataLine.open(format);

            sourceDataLine.start();

            System.out.println("format? :" + sourceDataLine.getFormat());

            sourceDataLine.write(soundbytes, 0, soundbytes.length);
            System.out.println(soundbytes.toString());
            sourceDataLine.drain();
            sourceDataLine.close();
        } catch (Exception e) {
            System.out.println("Not working in speakers...");
            e.printStackTrace();
        }
    }


}

The html code to call the applet :

<HTML>
<TITLE>Applet Test</TITLE>
<HEAD></HEAD>
<BODY>
<applet code="AppletTest.class" height="200" width="500">Applet</applet>
</BODY>
</HTML>

I have hosted the applet here

This is the android activity to send sound in form of datapackets :

public class SendActivity extends Activity {
    private Button startButton, stopButton;

    public byte[] buffer;
    public static DatagramSocket socket;
    private int port = 50005;
    AudioRecord recorder;

    private int sampleRate = 8000;
    @SuppressWarnings("deprecation")
    private int channelConfig = AudioFormat.CHANNEL_IN_MONO;
    private int audioFormat = AudioFormat.ENCODING_PCM_16BIT;
    int minBufSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig,
            audioFormat);
    private boolean status = true;


    int bufferSizeInBytes;
    int bufferSizeInShorts;
      int shortsRead;
      short audioBuffer[];

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_send);

        startButton = (Button) findViewById(R.id.start_button);
        stopButton = (Button) findViewById(R.id.stop_button);

        startButton.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {

                status = true;
                startStreaming();


            }

        });

        stopButton.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {

                status = false;
                recorder.release();
                Log.d("VS", "Recorder released");

            }

        });

        minBufSize += 5120;
        System.out.println("minBufSize: " + minBufSize);
    }


    public void startStreaming() {

        Thread streamThread = new Thread(new Runnable() {

            @Override
            public void run() {
                try {

                    DatagramSocket socket = new DatagramSocket();
                    Log.d("VS", "Socket Created");

                    byte[] buffer = new byte[minBufSize];

                    Log.d("VS", "Buffer created of size " + minBufSize);
                    DatagramPacket packet;

                    final InetAddress destination = InetAddress
                            .getByName("http://abhideepmallick.byethost16.com/");

//final InetAddress destination = InetAddress.getByName("192.168.1.20");//machine IP

Log.d("VS", "Address retrieved");

                    recorder = new AudioRecord(MediaRecorder.AudioSource.VOICE_RECOGNITION,
                            sampleRate, channelConfig, audioFormat,
                            minBufSize * 10);
                    Log.d("VS", "Recorder initialized");

                    recorder.startRecording();

                    while (status == true) {

                        // reading data from MIC into buffer
                        minBufSize = recorder.read(buffer, 0, buffer.length);

                        // putting buffer in the packet
                        packet = new DatagramPacket(buffer, buffer.length,
                                destination, port);

                        socket.send(packet);
                        System.out.println("MinBufferSize: " + minBufSize);

                    }

                } catch (UnknownHostException e) {
                    Log.e("VS", "UnknownHostException");
                } catch (IOException e) {
                    e.printStackTrace();
                    Log.e("VS", "IOException");
                }
            }

        });
        streamThread.start();
    }


}

Android layout file :

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".SendActivity" >



    <Button
        android:id="@+id/stop_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/start_button"
        android:layout_alignBottom="@+id/start_button"
        android:layout_toRightOf="@+id/start_button"
        android:text="Stop" />

    <Button
        android:id="@+id/start_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:layout_marginLeft="79dp"
        android:layout_marginTop="163dp"
        android:text="Start" />

</RelativeLayout>

What should I do to make the java class work as an applet?

Answer 1

I suppose you managed that the java plugin for the browser is up to date, in order to start the applet.

An applet has also a lifecylce like a activity.

The init() method is like a constructor, and the purpose of the start() method is to inform the applet should start executing.

So override the start method and call your listening method from there. For more information you could browse through this slide: http://de.slideshare.net/myrajendra/applet-life-cycle

An example can be found here: http://www.ugrad.cs.ubc.ca/~cs219/CourseNotes/Java/applets/lifecycle.html