A membership key may represent a membership to receive all datagrams sent
to the group, or it may be source-specific, meaning that it
represents a membership that receives only datagrams from a specific source
address. Whether or not a membership key is source-specific may be determined
by invoking its sourceAddress
method.
A membership key is valid upon creation and remains valid until the
membership is dropped by invoking the drop
method, or
the channel is closed. The validity of the membership key may be tested
by invoking its isValid
method.
Where a membership key is not source-specific and the underlying operation
system supports source filtering, then the block
and unblock
methods can be used to block or unblock multicast datagrams
from particular source addresses.
- Since:
- 1.7
- See Also:
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Constructor Summary
ModifierConstructorDescriptionprotected
Initializes a new instance of this class. -
Method Summary
Modifier and TypeMethodDescriptionabstract MembershipKey
block
(InetAddress source) Block multicast datagrams from the given source address.abstract MulticastChannel
channel()
Returns the channel for which this membership key was created.abstract void
drop()
Drop membership.abstract InetAddress
group()
Returns the multicast group for which this membership key was created.abstract boolean
isValid()
Tells whether or not this membership is valid.abstract NetworkInterface
Returns the network interface for which this membership key was created.abstract InetAddress
Returns the source address if this membership key is source-specific, ornull
if this membership is not source-specific.abstract MembershipKey
unblock
(InetAddress source) Unblock multicast datagrams from the given source address that was previously blocked using theblock
method.
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Constructor Details
-
MembershipKey
protected MembershipKey()Initializes a new instance of this class.
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-
Method Details
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isValid
public abstract boolean isValid()Tells whether or not this membership is valid.A multicast group membership is valid upon creation and remains valid until the membership is dropped by invoking the
drop
method, or the channel is closed.- Returns:
true
if this membership key is valid,false
otherwise
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drop
public abstract void drop()Drop membership.If the membership key represents a membership to receive all datagrams then the membership is dropped and the channel will no longer receive any datagrams sent to the group. If the membership key is source-specific then the channel will no longer receive datagrams sent to the group from that source address.
After membership is dropped it may still be possible to receive datagrams sent to the group. This can arise when datagrams are waiting to be received in the socket's receive buffer. After membership is dropped then the channel may
join
the group again in which case a new membership key is returned.Upon return, this membership object will be
invalid
. If the multicast group membership is already invalid then invoking this method has no effect. Once a multicast group membership is invalid, it remains invalid forever. -
block
Block multicast datagrams from the given source address.If this membership key is not source-specific, and the underlying operating system supports source filtering, then this method blocks multicast datagrams from the given source address. If the given source address is already blocked then this method has no effect. After a source address is blocked it may still be possible to receive datagrams from that source. This can arise when datagrams are waiting to be received in the socket's receive buffer.
- Parameters:
source
- The source address to block- Returns:
- This membership key
- Throws:
IllegalArgumentException
- If thesource
parameter is not a unicast address or is not the same address type as the multicast groupIllegalStateException
- If this membership key is source-specific or is no longer validUnsupportedOperationException
- If the underlying operating system does not support source filteringIOException
- If an I/O error occurs
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unblock
Unblock multicast datagrams from the given source address that was previously blocked using theblock
method.- Parameters:
source
- The source address to unblock- Returns:
- This membership key
- Throws:
IllegalStateException
- If the given source address is not currently blocked or the membership key is no longer valid
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channel
Returns the channel for which this membership key was created. This method will continue to return the channel even after the membership becomesinvalid
.- Returns:
- the channel
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group
Returns the multicast group for which this membership key was created. This method will continue to return the group even after the membership becomesinvalid
.- Returns:
- the multicast group
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networkInterface
Returns the network interface for which this membership key was created. This method will continue to return the network interface even after the membership becomesinvalid
.- Returns:
- the network interface
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sourceAddress
Returns the source address if this membership key is source-specific, ornull
if this membership is not source-specific.- Returns:
- The source address if this membership key is source-specific,
otherwise
null
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