6.2. UDP Communication¶
6.2.1. Dependencies¶
TCP communication requires the NET foundation library.
To use it, add the following dependency to your project’s module.ivy file:
<dependency org="ej.api" name="net" rev="1.1.2" />
6.2.2. Replacing the javax.microedition.io.Datagram class¶
Code using javax.microedition.io.Datagram can use java.net.DatagramSocket instead.
6.2.2.1. Write sample¶
The following snippet is extracted from the J2ME Javadoc.
datagram = connection.newDatagram(max);
// Reset prepares the datagram for writing new message.
datagram.reset();
// writeUTF automatically increases the datagram length.
datagram.writeUTF("hello world");
connection.send(datagram);
It can be adapted as follows:
byte[] buffer = new byte[max];
try (DatagramSocket socket = new DatagramSocket()) {
DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
// Set peer address + port
packet.setSocketAddress(new InetSocketAddress("host.com", 79));
// Prepares the datagram for writing message.
packet.setData("hello world".getBytes("UTF-8"));
// Sends the datagram
socket.send(packet);
}
6.2.2.2. Read sample¶
The following snippet is extracted from the J2ME Javadoc.
datagram = connection.newDatagram(max);
connection.receive(datagram);
message = datagram.readUTF();
It can be adapted as follows:
byte[] buffer = new byte[max];
try (DatagramSocket socket = new DatagramSocket()) {
DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
// Set peer address + port
packet.setSocketAddress(new InetSocketAddress("host.com", 79));
// Prepares the datagram for reading message.
packet.setLength(max);
// Sends the datagram
socket.receive(packet);
// Decode the message
int offset = packet.getOffset();
int length = packet.getLength();
String message = new String(buffer, offset, length, "UTF-8");
}