1. Sound effects and music
Java Sound API: javax.sound.sampled
8- or 16-bit samples
from 8,000Hz to 48,000Hz
mono or stereo
sound file formats: AIFF, AU, WAV
(Examples: 16-bit, mono, 44,100Hz, WAV)

2. Loading and playing a sound
try {
File file = new File(“…”);
AudioInputStream stream =
AudioSystem.getAudioInputStream(file);
AudioFormat format = stream.getFormat();
} catch(Exception ex) {
// IOException or UnsupportedAudioFileException }
DataLine.Info info =
new DataLine.Info(SourceDataLine.class,format);
line = (SourceDataLine) AudioSystem.getLine(info);
line.open(format,bufferSize);
// LineUnavailableException

3. try {
int numBytesRead = 0;
while (numBytesRead != -1) {
numBytesRead = stream.read(buffer, 0, buffer.length);
if (numBytesRead != -1) {
line.write(buffer, 0, numBytesRead); }
} catch (Exception ex) {
// IOException };
line.drain();
line.close();

4. Sound filter Examples: echo filter simulated 3D sound filter
SoundFilter class (abstract class):
filter(byte[] buffer, int offset, int length) – Filters an array of samples.
getRemainingSize() – Gets the remaining size, in bytes, that this filter can play after the sound is finished.
reset() – Resets the filter so that it can be used again on a different sound.

5. FilteredSoundStream
public class FilteredSoundStream extends FilterInputStream { …
public int read(byte[] samples, int offset, int length)
throws IOException {
int bytesRead = super.read(samples, offset, length);
if (bytesRead > 0) {
soundFilter.filter(samples, offset, bytesRead);
return bytesRead; };
if (remainingSize == REMAINING_SIZE_UNKNOWN) {
remainingSize = soundFilter.getRemainingSize();
remainingSize = remainingSize / 4 * 4;

6. if (remainingSize > 0) {
length = Math.min(length, remainingSize);
for (int i=offset; i<offset+length; i++) {
samples[i] = 0; };
soundFilter.filter(samples, offset, length);
remainingSize-=length;
return length;
} else {
return -1; }

7. Echo filter
Delay
Original sound First echo Second echo
delay: numbers of samples to delay (44,100Hz sound, 1 sec delay = 44,100 samples)
decay: value from 0 to 1
0 means no echo
1 means the echo is the same volume as the original sound

8. Emulating 3D sound
Many different effects are used to create 3D sounds.
Make sound diminish with distance so the farther away a sound source is, the quieter it is.
Pan sounds to the appropriate speaker.
Apply room effects so sound waves bounce off walls, creating echoes and reverberation.
Apply the Doppler effect so a sound source movement affect its pitch.

9. SoundManager The SoundManager class has the following features:
provides a common interface for loading and playing sounds (including filters),
extends the ThreadPool class,
each thread in the thread pool has its own buffer and line object (thread-local variables).

10. Playing music
Java Sound API provides MIDI sound capabilities in javax.sound.midi
synthesizes MIDI music through the use of a soundbank,
Java SDK includes a minimal-quality soundbank,
higher-quality soundbanks from
To play MIDI music, you need two objects:
Sequence object containing the data
Sequencer sending the Sequence to the MIDI synthesizer

11. Sequence sequence = MidiSystem.getSequence(new File(“…”));
Sequencer sequencer = MidiSystem.getSequencer();
sequencer.open();
sequencer.setSequence(sequence);
sequencer.start();
Adding or taking away an instrument (track):
sequencer.setTrackMute(trackNum, true);

12. Network programming Socket-based communication (java.net.*)
server sockets (class ServerSocket)
each server socket listens at a specific port
the server must be running before its clients initiate contact
after the sever socket is contacted by a client, a connection can be established
constructor ServerSocket(int port)
client sockets (class Socket)
on the client side, constructors
Socket(String host, int port)
Socket(InetAddress address, int port)
on the server side
returned by the accept method of the server socket
have an input and output stream

13. Example (Server)
...
try {
ServerSocket server = new ServerSocket(10997);
while (running) {
Socket client = server.accept();
InputStream in = client.getInputStream();
OutputStream out = client.getOutputStream();
// handle the client
in.close();
out.flush();
out.close();
client.close(); };
server.close();
} catch (Exception e) {
e.printStackTrace();

14. Example (Client) ... try { Socket socket = new Socket(host,10997);
InputStream in = socket.getInputStream();
OutputStream out = socket.getOutputStream();
// Send and receive data
in.close();
out.flush();
out.close();
socket.close();
} catch (Exception e) {
e.printStackTrace(); };

15. Network programming (cont’d)
The server in the previous example handles one client at a time.
just one client accepted at a time,
operations on streams are blocking,
Solution
use multiple threads (one for each client)

16. Example (Server)
...
try {
ServerSocket server = new ServerSocket(10997);
while (running) {
Socket client = server.accept();
new ClientHandler(client).start(); };
server.close();
} catch (Exception e) {
e.printStackTrace();

17. public class ClientHandler extends Thread {
private Socket client;
public ClientHandler(Socket client) {
this.client = client; }
public void run() {
try {
InputStream in = client.getInputStream();
OutputStream out = client.getOutputStream();
...
// handle the client
in.close();
out.flush();
out.close();
client.close();
} catch (Exception e) {
e.printStackTrace(); };

18. Example public class ChatterServer {
public static Vector clients = new Vector();
public static void main(String[] args) throws Exception {
try {
ServerSocket server = new ServerSocket(10997);
while (true) {
Socket client = server.accept();
ClientHandler clientHandler = new ClientHandler(client);
clients.add(clientHandler);
clientHandler.start(); };
} catch (Exception e) {
e.printStackTrace(); }

19. Example public class ClientHandler extends Thread {
private Socket client;
private String clientName;
private BufferedReader in;
private PrintWriter out;
public ClientHandler(Socket client) {
this.client = client;
try {
in = new BufferedReader(new InputStreamReader(
client.getInputStream()));
out = new PrintWriter(new OutputStreamWriter(
client.getOutputStream()));
} catch (Exception e) {
e.printStackTrace(); }; }

20. Example public String getClientName() { return clientName; }
public synchronized void sendMessage(String msg) {
if (out != null) {
out.println(msg);
out.flush(); };
public void broadcastMessage(String msg) {
for(Iterator it = ChatterServer.clients.iterator(); it.hasNext();) {
ClientHandler ch = (ClientHandler) it.next();
if (ch != this) ch.sendMessage(msg);

21. Example public void run() { if (in != null && out != null) { ...
while (true) {
String str = in.readLine();
if (str == null) break;
if (str.trim().equals("BYE")) break;
broadcastMessage("From " + clientName + ": " + str); };
broadcastMessage("User " + clientName + " has closed connection.");
client.close();
ChatterServer.clients.remove(this); }

22. Class InetAddress This class represents internet addresses:
InetAddress addr = InetAddress.getByName("sandcastle"));
byte[] b = {(byte) 139, (byte)57, (byte)96, (byte)6};
InetAddress addr = InetAddress.getByAddress(b)

23. JDK 1.4 NIO Libraries Channels (java.nio.channels.*) Interfaces
public void close();
public boolean isOpen();
ReadableByteChannel and WritableByteChannel
public int read(ByteBuffer dst);
public int write(ByteBuffer src);
ByteChannel
GatheringByteChannel and ScatteringByteChannel
long write(ByteBuffer[] srcs);
long write(ByteBuffer[] srcs, long offset, long length);
long read(ByteBuffer[] dsts);
long read(ByteBuffer[] dsts, long offset, long length);

24. NIO (cont.) Classes ServerSocketChannel ServerSocketChannel sSockChan;
sSockChan = ServerSocketChannel.open();
sSockChan.configureBlocking(false);
InetAddress addr = InetAddress.getLocalHost();
sSockChan.socket().bind(new InetSocketAddress(addr,PORT));
SocketChannel
SocketChannel has all the methods of ServerSocketChannel
methods for reading and writing
methods for managing the connection

25. NIO (cont.) sSockChan.accept(); (server)
SocketChannel.open(SocketAddress address); (client) or
channel = SocketChannel.open();
channel.connect(SocketAddress address);
DatagramChannel
using UDP (User Datagram Protocol) instead of TCP
UDP is an unreliable protocol.

26. NIO (cont.) Buffers Classes ByteBuffer CharBuffer DoubleBuffer
FloatBuffer
IntBuffer
LongBuffer
ShortBuffer
MappedByteBuffer
methods for querying and manipulating the capacity, position, limit, and mark of the buffer 1 2 3 4 5 6 7 8 9
mark
position
limit
capacity

27. NIO (cont.) FileChannel.read(ByteBuffer src, int o, int length);
SocketChannel.write(ByteBuffer src);
clear() – preparing a buffer for filling
flip() – preparing the buffer for draining 1 2 3 4 5 6 7 8 9
position
limit
capacity 1 2 3 4 5 6 7 8 9
position
limit
capacity 1 2 3 4 5 6 7 8 9
position
limit
capacity

28. NIO (cont.) rewind() – preparing the buffer for another draining
compact() – moves the elements between the current position and the limit to the beginning of the buffer
direct versus nondirect buffers 1 2 3 4 5 6 7 8 9
position
limit
capacity 1 2 3 4 5 6 7 8 9
position
limit
capacity

29. Selector and SelectionKey
Provide a mechanism for multiplexing access to channels.
register a channel (along with a set of operations that the selector should watch for)
chan.register(readSelector,
SelectionKey.OP_READ,
new StringBuffer());
OP_ACCEPT
OP_CONNECT
OP_READ
OP_WRITE
watching the channels
readSelector.selectNow();
select() blocks until at least one channel has activity
select(long timeout) as select() with timeout
selectNow() returns immediately

30. Selector (cont.) accessing the channels readSelector.selectedKeys();
returns a Set of SelectionKeys
use an Iterator to get the keys
key.channel() returns the channel

31. Example: ChatterBox
ChatterServer is a multi-user chat application that allows for any
number of users to connect to the server and send text messages to one
another.
The server needs to perform the following main functions:
Accept client connections
Read messages from clients
Write messages to clients
Handle disconnections (graceful or otherwise)

32. ChatterServer Important attributes:
private ServerSocketChannel sSockChan;
private Selector readSelector;
private LinkedList clients;
private ByteBuffer readBuffer;
private ByteBuffer writeBuffer;
private CharsetDecoder asciiDecoder;
private Logger log = Logger.getLogger(ChatterServer.class);

33. private static final int PORT = 10997;
private void initServerSocket() {
try {
// open a non-blocking server socket channel
sSockChan = ServerSocketChannel.open();
sSockChan.configureBlocking(false);
// bind to localhost on designated port
InetAddress addr = InetAddress.getLocalHost();
sSockChan.socket().bind(
new InetSocketAddress(addr, PORT));
// get a selector for multiplexing the client channels
readSelector = Selector.open(); }
catch (Exception e) {
log.error("error initializing server", e);

34. private void acceptNewConnections() {
try {
SocketChannel clientChannel;
while ((clientChannel = sSockChan.accept()) != null) {
addNewClient(clientChannel);
log.info("got connection from: " clientChannel.socket().getInetAddress());
sendBroadcastMessage("login from: " clientChannel.socket().getInetAddress(), clientChannel);
sendMessage(clientChannel, "\n\nWelcome to ChatterBox, there are " + clients.size() + " users online.\n");
sendMessage(clientChannel, "Type 'quit' to exit.\n"); }
catch (IOException ioe) {
log.warn("error during accept(): ", ioe);
catch (Exception e) {
log.error("exception in acceptNewConnections()", e);

35. private void addNewClient(SocketChannel chan) {
// add to our list
clients.add(chan);
// register the channel with the selector
// store a new StringBuffer as the Key's attachment for
// holding partially read messages
try {
chan.configureBlocking( false);
SelectionKey readKey = chan.register(readSelector, SelectionKey.OP_READ, new StringBuffer()); }
catch (ClosedChannelException cce) {
catch (IOException ioe) {

36. private void sendMessage(SocketChannel channel, String mesg) {
prepWriteBuffer(mesg);
channelWrite(channel, writeBuffer); }
private void sendBroadcastMessage(String mesg, SocketChannel from) {
Iterator i = clients.iterator();
while (i.hasNext()) {
SocketChannel channel = (SocketChannel)i.next();
if (channel != from) channelWrite(channel, writeBuffer);
private void prepWriteBuffer(String mesg) {
writeBuffer.clear();
writeBuffer.put(mesg.getBytes());
writeBuffer.putChar('\n');
writeBuffer.flip();

37. private void channelWrite(SocketChannel channel, ByteBuffer writeBuffer) {
long nbytes = 0;
long toWrite = writeBuffer.remaining();
// loop on the channel.write() call since it will not necessarily
// write all bytes in one shot
try {
while (nbytes != toWrite) {
nbytes += channel.write(writeBuffer);
Thread.sleep(CHANNEL_WRITE_SLEEP); }
catch (InterruptedException e) {}
catch (ClosedChannelException cce) {
catch (Exception e) {
// get ready for another write if needed
writeBuffer.rewind();

38. private void readIncomingMessages() {
try {
readSelector.selectNow();
Set readyKeys = readSelector.selectedKeys();
Iterator i = readyKeys.iterator();
while (i.hasNext()) {
SelectionKey key = (SelectionKey) i.next();
i.remove();
SocketChannel channel = (SocketChannel) key.channel();
readBuffer.clear();
long nbytes = channel.read(readBuffer);
if (nbytes == -1) {
log.info("disconnect: " channel.socket().getInetAddress() + ",
end-of-stream");
channel.close();
clients.remove(channel);
sendBroadcastMessage("logout: " +
channel.socket().getInetAddress() , channel); }

39. else {
StringBuffer sb = (StringBuffer)key.attachment();
readBuffer.flip( );
String str = asciiDecoder.decode(readBuffer).toString();
readBuffer.clear( );
sb.append( str);
String line = sb.toString(); …
sendBroadcastMessage(channel.socket().getInetAddress() +
": " + line, channel); }

40. ChatterClient The ChatterClient needs to perform three tasks:
Connect to the server
Send messages
Receive messages
The client uses two threads, one for console input/writing and the main
execution thread.

41. private void connect(String hostname) {
try {
readSelector = Selector.open();
InetAddress addr =
InetAddress.getByName(hostname);
channel = SocketChannel.open(new
InetSocketAddress(addr, PORT));
channel.configureBlocking(false);
channel.register(readSelector, SelectionKey.OP_READ,
new StringBuffer()); }
catch (UnknownHostException uhe) {
catch (ConnectException ce) {
catch (Exception e) {