MembershipKey (Java Platform SE 8 ) (original) (raw)

• java.lang.Object

• • java.nio.channels.MembershipKey

• ---

public abstract class MembershipKey
extends Object
A token representing the membership of an Internet Protocol (IP) multicast group.
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:
MulticastChannel

• • Constructor Summary

  Constructors

  Modifier	Constructor	Description
  protected	MembershipKey()	Initializes a new instance of this class.

  • Method Summary

  All Methods Instance Methods Abstract Methods

  Modifier and Type	Method	Description
  abstract 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	networkInterface()	Returns the network interface for which this membership key was created.
  abstract InetAddress	sourceAddress()	Returns the source address if this membership key is source-specific, or null 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 the block method.

     * ### Methods inherited from class java.lang.[Object](../../../java/lang/Object.html "class in java.lang")  
     `[clone](../../../java/lang/Object.html#clone--), [equals](../../../java/lang/Object.html#equals-java.lang.Object-), [finalize](../../../java/lang/Object.html#finalize--), [getClass](../../../java/lang/Object.html#getClass--), [hashCode](../../../java/lang/Object.html#hashCode--), [notify](../../../java/lang/Object.html#notify--), [notifyAll](../../../java/lang/Object.html#notifyAll--), [toString](../../../java/lang/Object.html#toString--), [wait](../../../java/lang/Object.html#wait--), [wait](../../../java/lang/Object.html#wait-long-), [wait](../../../java/lang/Object.html#wait-long-int-)`

• • Constructor Detail

     * #### MembershipKey  
     protected MembershipKey()  
     Initializes a new instance of this class.  

  • Method Detail

    * #### 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](../../../java/nio/channels/MembershipKey.html#drop--) method, or the channel is closed.  
    Returns:  
    `true` if this membership key is valid, `false` otherwise  
    * #### 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](../../../java/nio/channels/MulticastChannel.html#join-java.net.InetAddress-java.net.NetworkInterface-) the group again in which case a new membership key is returned.  
     Upon return, this membership object will be [invalid](../../../java/nio/channels/MembershipKey.html#isValid--). 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  
    public abstract [MembershipKey](../../../java/nio/channels/MembershipKey.html "class in java.nio.channels") block([InetAddress](../../../java/net/InetAddress.html "class in java.net") source)  
                                 throws [IOException](../../../java/io/IOException.html "class in java.io")  
    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](../../../java/lang/IllegalArgumentException.html "class in java.lang")` \- If the `source` parameter is not a unicast address or is not the same address type as the multicast group  
    `[IllegalStateException](../../../java/lang/IllegalStateException.html "class in java.lang")` \- If this membership key is source-specific or is no longer valid  
    `[UnsupportedOperationException](../../../java/lang/UnsupportedOperationException.html "class in java.lang")` \- If the underlying operating system does not support source filtering  
    `[IOException](../../../java/io/IOException.html "class in java.io")` \- If an I/O error occurs  
    * #### unblock  
    public abstract [MembershipKey](../../../java/nio/channels/MembershipKey.html "class in java.nio.channels") unblock([InetAddress](../../../java/net/InetAddress.html "class in java.net") source)  
    Unblock multicast datagrams from the given source address that was previously blocked using the [block](../../../java/nio/channels/MembershipKey.html#block-java.net.InetAddress-) method.  
    Parameters:  
    `source` \- The source address to unblock  
    Returns:  
    This membership key  
    Throws:  
    `[IllegalStateException](../../../java/lang/IllegalStateException.html "class in java.lang")` \- If the given source address is not currently blocked or the membership key is no longer valid  
    * #### channel  
    public abstract [MulticastChannel](../../../java/nio/channels/MulticastChannel.html "interface in java.nio.channels") channel()  
    Returns the channel for which this membership key was created. This method will continue to return the channel even after the membership becomes [invalid](../../../java/nio/channels/MembershipKey.html#isValid--).  
    Returns:  
    the channel  
    * #### group  
    public abstract [InetAddress](../../../java/net/InetAddress.html "class in java.net") group()  
    Returns the multicast group for which this membership key was created. This method will continue to return the group even after the membership becomes [invalid](../../../java/nio/channels/MembershipKey.html#isValid--).  
    Returns:  
    the multicast group  
    * #### networkInterface  
    public abstract [NetworkInterface](../../../java/net/NetworkInterface.html "class in java.net") 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 becomes [invalid](../../../java/nio/channels/MembershipKey.html#isValid--).  
    Returns:  
    the network interface  
    * #### sourceAddress  
    public abstract [InetAddress](../../../java/net/InetAddress.html "class in java.net") sourceAddress()  
    Returns the source address if this membership key is source-specific, or `null` if this membership is not source-specific.  
    Returns:  
    The source address if this membership key is source-specific, otherwise `null`

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