ChannelGroup (The Netty Project API Reference (3.5.13.Final))

All Superinterfaces:: Collection<Channel>, Comparable<ChannelGroup>, Iterable<Channel>, Set<Channel>

All Known Implementing Classes:: DefaultChannelGroup

public interface ChannelGroup
extends Set<Channel>, Comparable<ChannelGroup>

A thread-safe Set that contains open Channels and provides various bulk operations on them. Using ChannelGroup, you can categorize Channels into a meaningful group (e.g. on a per-service or per-state basis.) A closed Channel is automatically removed from the collection, so that you don't need to worry about the life cycle of the added Channel. A Channel can belong to more than one ChannelGroup.

Broadcast a message to multiple `Channel`s

If you need to broadcast a message to more than one Channel, you can add the Channels associated with the recipients and call write(Object):

 ChannelGroup recipients = new DefaultChannelGroup();
 recipients.add(channelA);
 recipients.add(channelB);
 ..
 recipients.write(ChannelBuffers.copiedBuffer(
         "Service will shut down for maintenance in 5 minutes.",
         CharsetUtil.UTF_8));

Simplify shutdown process with `ChannelGroup`

If both ServerChannels and non-ServerChannels exist in the same ChannelGroup, any requested I/O operations on the group are performed for the ServerChannels first and then for the others.

This rule is very useful when you shut down a server in one shot:

 ChannelGroup allChannels = new DefaultChannelGroup();

 public static void main(String[] args) throws Exception {
     ServerBootstrap b = new ServerBootstrap(..);
     ...

     // Start the server
     b.getPipeline().addLast("handler", new MyHandler());
     Channel serverChannel = b.bind(..);
     allChannels.add(serverChannel);

     ... Wait until the shutdown signal reception ...

     // Close the serverChannel and then all accepted connections.
     allChannels.close().awaitUninterruptibly();
     b.releaseExternalResources();
 }

 public class MyHandler extends SimpleChannelUpstreamHandler {
     @Override
     public void channelOpen(ChannelHandlerContext ctx, ChannelStateEvent e) {
         // Add all open channels to the global group so that they are
         // closed on shutdown.
         allChannels.add(e.getChannel());
     }
 }

Method Summary

Methods
Modifier and Type	Method and Description
`ChannelGroupFuture`	`close()` Closes all `Channel`s in this group.
`ChannelGroupFuture`	`disconnect()` Disconnects all `Channel`s in this group from their remote peers.
`Channel`	`find(Integer id)` Returns the `Channel` whose ID matches the specified integer.
`String`	`getName()` Returns the name of this group.
`ChannelGroupFuture`	`setInterestOps(int interestOps)` Calls `Channel.setInterestOps(int)` for all `Channel`s in this group with the specified `interestOps`.
`ChannelGroupFuture`	`setReadable(boolean readable)` Calls `Channel.setReadable(boolean)` for all `Channel`s in this group with the specified boolean flag.
`ChannelGroupFuture`	`unbind()` Unbinds all `Channel`s in this group from their local address.
`ChannelGroupFuture`	`write(Object message)` Writes the specified `message` to all `Channel`s in this group.
`ChannelGroupFuture`	`write(Object message, SocketAddress remoteAddress)` Writes the specified `message` with the specified `remoteAddress` to all `Channel`s in this group.

Methods inherited from interface java.util.Set
add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, remove, removeAll, retainAll, size, toArray, toArray

Methods inherited from interface java.lang.Comparable
compareTo

- Method Detail
  - getName
```
String getName()
```
    Returns the name of this group. A group name is purely for helping you to distinguish one group from others.
  - find
```
Channel find(Integer id)
```
    Returns the Channel whose ID matches the specified integer.
    
    Returns:
    the matching Channel if found. null otherwise.
  - setInterestOps
```
ChannelGroupFuture setInterestOps(int interestOps)
```
    Calls Channel.setInterestOps(int) for all Channels in this group with the specified interestOps. Please note that this operation is asynchronous as Channel.setInterestOps(int) is.
    
    Returns:
    the ChannelGroupFuture instance that notifies when the operation is done for all channels
  - setReadable
```
ChannelGroupFuture setReadable(boolean readable)
```
    Calls Channel.setReadable(boolean) for all Channels in this group with the specified boolean flag. Please note that this operation is asynchronous as Channel.setReadable(boolean) is.
    
    Returns:
    the ChannelGroupFuture instance that notifies when the operation is done for all channels
  - write
```
ChannelGroupFuture write(Object message)
```
    Writes the specified message to all Channels in this group. If the specified message is an instance of ChannelBuffer, it is automatically duplicated to avoid a race condition. Please note that this operation is asynchronous as Channel.write(Object) is.
    
    Returns:
    the ChannelGroupFuture instance that notifies when the operation is done for all channels
  - write
```
ChannelGroupFuture write(Object message,
                       SocketAddress remoteAddress)
```
    Writes the specified message with the specified remoteAddress to all Channels in this group. If the specified message is an instance of ChannelBuffer, it is automatically duplicated to avoid a race condition. Please note that this operation is asynchronous as Channel.write(Object, SocketAddress) is.
    
    Returns:
    the ChannelGroupFuture instance that notifies when the operation is done for all channels
  - disconnect
```
ChannelGroupFuture disconnect()
```
    Disconnects all Channels in this group from their remote peers.
    
    Returns:
    the ChannelGroupFuture instance that notifies when the operation is done for all channels
  - unbind
```
ChannelGroupFuture unbind()
```
    Unbinds all Channels in this group from their local address.
    
    Returns:
    the ChannelGroupFuture instance that notifies when the operation is done for all channels
  - close
```
ChannelGroupFuture close()
```
    Closes all Channels in this group. If the Channel is connected to a remote peer or bound to a local address, it is automatically disconnected and unbound.
    
    Returns:
    the ChannelGroupFuture instance that notifies when the operation is done for all channels

Interface ChannelGroup

Broadcast a message to multiple Channels

Simplify shutdown process with ChannelGroup

Method Summary

Methods inherited from interface java.util.Set

Methods inherited from interface java.lang.Comparable

Method Detail

getName

find

setInterestOps

setReadable

write

write

disconnect

unbind

close

Broadcast a message to multiple `Channel`s

Simplify shutdown process with `ChannelGroup`