java.lang.Object
java.net.DatagramSocketImpl
- All Implemented Interfaces:
SocketOptions
public abstract class DatagramSocketImpl extends Object implements SocketOptions
Abstract datagram and multicast socket implementation base class.
- Implementation Note:
- Sockets created with the
DatagramSocket
andMulticastSocket
public constructors historically delegated all socket operations to aDatagramSocketImpl
implementation named "PlainDatagramSocketImpl".DatagramSocket
andMulticastSocket
have since been changed to a new implementation based onDatagramChannel
. The JDK continues to ship with the older implementation to allow code to run that depends on unspecified behavior that differs between the old and new implementations. The old implementation will be used if the Java virtual machine is started with the system propertyjdk.net.usePlainDatagramSocketImpl
set to use the old implementation. It may also be set in the JDK's network configuration file, located in${java.home}/conf/net.properties
. The value of the property is the string representation of a boolean. If set without a value then it defaults totrue
, hence running with-Djdk.net.usePlainDatagramSocketImpl
or-Djdk.net.usePlainDatagramSocketImpl=true
will configure the Java virtual machine to use the old implementation. The property and old implementation will be removed in a future version. - Since:
- 1.1
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Field Summary
Fields Modifier and Type Field Description protected FileDescriptor
fd
The file descriptor object.protected int
localPort
The local port number.Fields declared in interface java.net.SocketOptions
IP_MULTICAST_IF, IP_MULTICAST_IF2, IP_MULTICAST_LOOP, IP_TOS, SO_BINDADDR, SO_BROADCAST, SO_KEEPALIVE, SO_LINGER, SO_OOBINLINE, SO_RCVBUF, SO_REUSEADDR, SO_REUSEPORT, SO_SNDBUF, SO_TIMEOUT, TCP_NODELAY
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Constructor Summary
Constructors Constructor Description DatagramSocketImpl()
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Method Summary
Modifier and Type Method Description protected abstract void
bind(int lport, InetAddress laddr)
Binds a datagram socket to a local port and address.protected abstract void
close()
Close the socket.protected void
connect(InetAddress address, int port)
Connects a datagram socket to a remote destination.protected abstract void
create()
Creates a datagram socket.protected void
disconnect()
Disconnects a datagram socket from its remote destination.protected FileDescriptor
getFileDescriptor()
Gets the datagram socket file descriptor.protected int
getLocalPort()
Gets the local port.protected <T> T
getOption(SocketOption<T> name)
Called to get a socket option.protected abstract int
getTimeToLive()
Retrieve the TTL (time-to-live) option.protected abstract byte
getTTL()
Deprecated.use getTimeToLive instead.protected abstract void
join(InetAddress inetaddr)
Join the multicast group.protected abstract void
joinGroup(SocketAddress mcastaddr, NetworkInterface netIf)
Join the multicast group.protected abstract void
leave(InetAddress inetaddr)
Leave the multicast group.protected abstract void
leaveGroup(SocketAddress mcastaddr, NetworkInterface netIf)
Leave the multicast group.protected abstract int
peek(InetAddress i)
Peek at the packet to see who it is from.protected abstract int
peekData(DatagramPacket p)
Peek at the packet to see who it is from.protected abstract void
receive(DatagramPacket p)
Receive the datagram packet.protected abstract void
send(DatagramPacket p)
Sends a datagram packet.protected <T> void
setOption(SocketOption<T> name, T value)
Called to set a socket option.protected abstract void
setTimeToLive(int ttl)
Set the TTL (time-to-live) option.protected abstract void
setTTL(byte ttl)
Deprecated.use setTimeToLive instead.protected Set<SocketOption<?>>
supportedOptions()
Returns a set of SocketOptions supported by this impl and by this impl's socket (DatagramSocket or MulticastSocket)Methods declared in class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
Methods declared in interface java.net.SocketOptions
getOption, setOption
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Field Details
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localPort
protected int localPortThe local port number. -
fd
The file descriptor object.
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Constructor Details
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DatagramSocketImpl
public DatagramSocketImpl()
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Method Details
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create
Creates a datagram socket.- Throws:
SocketException
- if there is an error in the underlying protocol, such as a TCP error.
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bind
Binds a datagram socket to a local port and address.- Parameters:
lport
- the local portladdr
- the local address- Throws:
SocketException
- if there is an error in the underlying protocol, such as a TCP error.
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send
Sends a datagram packet. The packet contains the data and the destination address to send the packet to.- Parameters:
p
- the packet to be sent.- Throws:
IOException
- if an I/O exception occurs while sending the datagram packet.PortUnreachableException
- may be thrown if the socket is connected to a currently unreachable destination. Note, there is no guarantee that the exception will be thrown.
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connect
Connects a datagram socket to a remote destination. This associates the remote address with the local socket so that datagrams may only be sent to this destination and received from this destination. This may be overridden to call a native system connect.If the remote destination to which the socket is connected does not exist, or is otherwise unreachable, and if an ICMP destination unreachable packet has been received for that address, then a subsequent call to send or receive may throw a PortUnreachableException. Note, there is no guarantee that the exception will be thrown.
- Parameters:
address
- the remote InetAddress to connect toport
- the remote port number- Throws:
SocketException
- may be thrown if the socket cannot be connected to the remote destination- Since:
- 1.4
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disconnect
protected void disconnect()Disconnects a datagram socket from its remote destination.- Since:
- 1.4
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peek
Peek at the packet to see who it is from. Updates the specifiedInetAddress
to the address which the packet came from.- Parameters:
i
- an InetAddress object- Returns:
- the port number which the packet came from.
- Throws:
IOException
- if an I/O exception occursPortUnreachableException
- may be thrown if the socket is connected to a currently unreachable destination. Note, there is no guarantee that the exception will be thrown.
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peekData
Peek at the packet to see who it is from. The data is copied into the specifiedDatagramPacket
. The data is returned, but not consumed, so that a subsequent peekData/receive operation will see the same data.- Parameters:
p
- the Packet Received.- Returns:
- the port number which the packet came from.
- Throws:
IOException
- if an I/O exception occursPortUnreachableException
- may be thrown if the socket is connected to a currently unreachable destination. Note, there is no guarantee that the exception will be thrown.- Since:
- 1.4
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receive
Receive the datagram packet.- Parameters:
p
- the Packet Received.- Throws:
IOException
- if an I/O exception occurs while receiving the datagram packet.PortUnreachableException
- may be thrown if the socket is connected to a currently unreachable destination. Note, there is no guarantee that the exception will be thrown.
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setTTL
Deprecated.use setTimeToLive instead.Set the TTL (time-to-live) option.- Parameters:
ttl
- a byte specifying the TTL value- Throws:
IOException
- if an I/O exception occurs while setting the time-to-live option.- See Also:
getTTL()
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getTTL
Deprecated.use getTimeToLive instead.Retrieve the TTL (time-to-live) option.- Returns:
- a byte representing the TTL value
- Throws:
IOException
- if an I/O exception occurs while retrieving the time-to-live option- See Also:
setTTL(byte)
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setTimeToLive
Set the TTL (time-to-live) option.- Parameters:
ttl
- anint
specifying the time-to-live value- Throws:
IOException
- if an I/O exception occurs while setting the time-to-live option.- See Also:
getTimeToLive()
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getTimeToLive
Retrieve the TTL (time-to-live) option.- Returns:
- an
int
representing the time-to-live value - Throws:
IOException
- if an I/O exception occurs while retrieving the time-to-live option- See Also:
setTimeToLive(int)
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join
Join the multicast group.- Parameters:
inetaddr
- multicast address to join.- Throws:
IOException
- if an I/O exception occurs while joining the multicast group.
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leave
Leave the multicast group.- Parameters:
inetaddr
- multicast address to leave.- Throws:
IOException
- if an I/O exception occurs while leaving the multicast group.
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joinGroup
protected abstract void joinGroup(SocketAddress mcastaddr, NetworkInterface netIf) throws IOExceptionJoin the multicast group.- Parameters:
mcastaddr
- address to join.netIf
- specifies the local interface to receive multicast datagram packets- Throws:
IOException
- if an I/O exception occurs while joining the multicast group- Since:
- 1.4
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leaveGroup
protected abstract void leaveGroup(SocketAddress mcastaddr, NetworkInterface netIf) throws IOExceptionLeave the multicast group.- Parameters:
mcastaddr
- address to leave.netIf
- specified the local interface to leave the group at- Throws:
IOException
- if an I/O exception occurs while leaving the multicast group- Since:
- 1.4
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close
protected abstract void close()Close the socket. -
getLocalPort
protected int getLocalPort()Gets the local port.- Returns:
- an
int
representing the local port value
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getFileDescriptor
Gets the datagram socket file descriptor.- Returns:
- a
FileDescriptor
object representing the datagram socket file descriptor
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setOption
Called to set a socket option.- Implementation Requirements:
- The default implementation of this method first checks that the given
socket option
name
is not null, then throwsUnsupportedOperationException
. Subclasses should override this method with an appropriate implementation. - Type Parameters:
T
- The type of the socket option value- Parameters:
name
- The socket optionvalue
- The value of the socket option. A value ofnull
may be valid for some options.- Throws:
UnsupportedOperationException
- if the DatagramSocketImpl does not support the optionIllegalArgumentException
- if the value is not valid for the optionIOException
- if an I/O error occurs, or if the socket is closedNullPointerException
- if name isnull
- Since:
- 9
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getOption
Called to get a socket option.- Implementation Requirements:
- The default implementation of this method first checks that the given
socket option
name
is not null, then throwsUnsupportedOperationException
. Subclasses should override this method with an appropriate implementation. - Type Parameters:
T
- The type of the socket option value- Parameters:
name
- The socket option- Returns:
- the socket option
- Throws:
UnsupportedOperationException
- if the DatagramSocketImpl does not support the optionIOException
- if an I/O error occurs, or if the socket is closedNullPointerException
- if name isnull
- Since:
- 9
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supportedOptions
Returns a set of SocketOptions supported by this impl and by this impl's socket (DatagramSocket or MulticastSocket)- Implementation Requirements:
- The default implementation of this method returns an empty set. Subclasses should override this method with an appropriate implementation.
- Returns:
- a Set of SocketOptions
- Since:
- 9
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