miktim/java-udpchannel: Java 7+/Android 8+ UDP client and server package based on the Java DatagramChannel class

Based on Java's DatagramChannel class, which supports source-specific multicast

Notes:

- The UDP protocol does not guarantee datagram delivery, ordering, or duplicate protection.

- The maximum safe UDP payload size is ~508 bytes.

- Don't forget to open the required UDP port in your firewall.

The jar ./dist/udpchannel-... file was generated with debugging info using JDK1.8 for target JRE1.7

package org.miktim.udpchannel;

Overview:

Class UdpChannel implements Closeable, AutoCloseable;

Constants:

static final String VERSION = "2.1.0";

Further in the text: "remote address", "remote port", "remote socket" means "remote" parameter of the constructor.

Constructors:

Creates an unbinded channel with reuse enabled, broadcast on, loopback disabled and one hop.

UdpChannel(String mode, InetSocketAddress remoteSoc, NetworkInterface intf) throws IOException;

UdpChannel(String mode, InetSocketAddress remoteSoc, String intfName) throws IOException;

- the mode is one of the:

"AUTO" : autodetection by remote address type (ipv4/ipv6)

"DEFAULT" : system default

"INET" : StandardProtocolFamily.INET

"INET6" : StandardProtocolFamily.INET6

"UNIX" : StandardProtocolFamily.UNIX (Android)

UdpChannel(InetSocketAddress remoteSoc, NetworkInterface intf) throws IOException;

UdpChannel(InetSocketAddress remoteSoc, String intfName) throws IOException;

- autodetection of the protocol family of the created channel by the type of the remote address (ipv4/ipv6).

Methods:

static boolean isAvailable(int port);

- checks whether the port is available.

static boolean seemsBroadcast(InetAddress addr);

- returns true if ipv4 address ends in .255

DatagramChannel getChannel();

String getMode();

- returns channel creation mode

DatagramSocket getSocket();

InetSocketAddress getRemote();

InetSocketAddress getLocal();

- returns socket address with interfaceAddr/remotePort;

- selected interface address (ipv4/ipv6) depends on remote address

boolean isOpen();

boolean isMulticast();

- returns true if the remote address is multicast

boolean isBound();

UdpChannel bind() throws IOException;

- an unbound channel binds to the remotePort;

UdpChannel bind(InetSocketAddress soc) throws IOException;

- binds channel to the specified socket

boolean isConnected();

UdpChannel connect() throws IOException;

- connects to remote socket

UdpChannel disconnect() throws IOException;

UdpChannel setReuseAddress(boolean enable) throws SocketException;

- enable/disable reuse of net channel

boolean getReuseAddress();

- enabled by default

UdpChannel setBroadcast(boolean on) throws IOException;

boolean getBroadcast() throws IOException;

- returns true if the channel is broadcast

UdpChannel setReceiveBufferSize(int size) throws IOException;

int getReceiveBufferSize() throws IOException;

UdpChannel setSendBufferSize(int size) throws IOException;

int getSendBufferSize() throws IOException;

UdpChannel setLoopbackMode(boolean disable) throws IOException;

- false enables loopback

boolean getLoopbackMode() throws SocketException;

UdpChannel setTimeToLive(int ttl) throws IOException;

int getTimeToLive() throws IOException;

NetworkInterface getNetworkInterface();

UdpChannel setNetworkInterface(NetworkInterface intf);

MembershipKey joinGroup() throws IOException;

- joins to the remote address group via the network interface;

MembershipKey joinGroup(InetAddress source) throws IOException;

- joins to the remote address group via the network interface;

- the resulting membership key is source-specific.

All send/receive methods binds unbouded channel to the remote port (0.0.0.0/remotePort);

int send(byte[] buf) throws IOException;

- sends datagram to remote address/port

- returns the number of bytes sent

int send(byte[] buf, SocketAddress target) throws IOException;

- sends datagram to specified target socket

- returns the number of bytes sent

void send(DatagramPacket dp) throws IOException;

- sends datagram packet to its own address/port or,

if the packet address is null, to the remote address/port

boolean isReceiving();

- returns true if the channel receives datagrams

UdpChannel setPayloadSize(int size);

- sets the payload buffer length for receiving packets

int getPayloadSize();

- default: 1500 bytes

void receive(UdpSocket.Handler handler) throws IOException;

- calls handler.onStart, starts receiving datagrams

void close();

- [stops receiving, calls handler.onClose,] close channel

Interface UdpChannel.Handler

void onStart(UdpChannel uc);

void onError(UdpChannel uc, Exception e);

void onClose(UdpChannel uc);

- called BEFORE closing the socket

void onPacket(UdpChannel uc, DatagramPacket dp);

}

@Override

String toString();

- returns a string with channel info of the form:

"INET UdpChannel remote: MCG /224.0.1.191:9099 bound to: /0.0.0.0:9099

Options:

SO_SNDBUF: 106496 SO_RCVBUF: 106496 SO_REUSEADDR: false SO_BROADCAST: false

IP_TOS: 0 IP_MULTICAST_IF: eth1 IP_MULTICAST_TTL: 1 IP_MULTICAST_LOOP: false"

Helpful Links:

- DatagramChannel:

https://docs.oracle.com/javase/8/docs/api/java/nio/channels/DatagramChannel.html

https://docs.oracle.com/javase/8/docs/api/java/nio/channels/MulticastChannel.html

- IANA address and port registry:

https://www.iana.org/assignments/multicast-addresses/multicast-addresses.xhtml

https://www.iana.org/assignments/ipv6-multicast-addresses/ipv6-multicast-addresses.xhtml

https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml

- Android Multicast Troubleshooting:

https://stackoverflow.com/questions/13221736/android-device-not-receiving-multicast-package

https://stackoverflow.com/questions/27917605/android-multicastsocket-joingroup-doesnt-trigger-sending-igmp-message

java-udpchannel

Описание

Языки