Netty 5.0.0.Alpha5 · io.netty5.channel.ChannelHandlerContext

Enables a ChannelHandler to interact with its ChannelPipeline and other handlers. Among other things a handler can notify the next ChannelHandler in the ChannelPipeline as well as modify the ChannelPipeline it belongs to dynamically.

Notify

You can notify the closest handler in the same ChannelPipeline by calling one of the various methods provided here. Please refer to ChannelPipeline to understand how an event flows.

Modifying a pipeline

You can get the ChannelPipeline your handler belongs to by calling pipeline(). A non-trivial application could insert, remove, or replace handlers in the pipeline dynamically at runtime.

Retrieving for later use

You can keep the ChannelHandlerContext for later use, such as triggering an event outside the handler methods, even from a different thread.

public class MyHandler extends ChannelHandler {

    private ChannelHandlerContext ctx;

    public void handlerAdded(ChannelHandlerContext ctx) {
        this.ctx = ctx;
    }

    public void login(String username, password) {
        ctx.write(new LoginMessage(username, password));
    }
    ...
}

A handler can have more than one context

Please note that a ChannelHandler instance can be added to more than one ChannelPipeline. It means a single ChannelHandler instance can have more than one ChannelHandlerContext and therefore the single instance can be invoked with different ChannelHandlerContexts if it is added to one or more ChannelPipelines more than once.

Additional resources worth reading

Please refer to the ChannelHandler, and ChannelPipeline to find out more about inbound and outbound operations, what fundamental differences they have, how they flow in a pipeline, and how to handle the operation in your application.

Modifier and Type	Method and Description
public default BufferAllocator	bufferAllocator() Return the assigned `BufferAllocator` which will be used to allocate `Buffer`s.
public default Channel	channel() Return the `Channel` which is bound to the `ChannelHandlerContext`.
public ChannelHandlerContext	fireChannelActive() Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelActive. A `Channel` is active now, which means it is connected.
public ChannelHandlerContext	fireChannelExceptionCaught(Throwable cause) Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelExceptionCaught. A `Channel` received an `Throwable` in one of its inbound operations.
public ChannelHandlerContext	fireChannelInactive() Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelInactive. A `Channel` is inactive now, which means it is closed.
public ChannelHandlerContext	fireChannelInboundEvent(Object evt) Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelInboundEvent. A `Channel` received a custom defined inbound event.
public ChannelHandlerContext	fireChannelRead(Object msg) Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelRead. A `Channel` received a message.
public ChannelHandlerContext	fireChannelReadComplete() Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelReadComplete. Triggers an `ChannelHandler#channelReadComplete(ChannelHandlerContext)` event to the next `ChannelHandler` in the `ChannelPipeline`.
public ChannelHandlerContext	fireChannelRegistered() Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelRegistered. A `Channel` was registered to its `EventLoop`.
public ChannelHandlerContext	fireChannelShutdown(ChannelShutdownDirection direction) Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelShutdown. A `Channel` was shutdown in a specific direction.
public ChannelHandlerContext	fireChannelUnregistered() Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelUnregistered. A `Channel` was unregistered from its `EventLoop`.
public ChannelHandlerContext	fireChannelWritabilityChanged() Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelWritabilityChanged. Triggers an `ChannelHandler#channelWritabilityChanged(ChannelHandlerContext)` event to the next `ChannelHandler` in the `ChannelPipeline`.
public ChannelHandlerContext	flush() Redeclares io.netty5.channel.ChannelOutboundInvoker.flush. Request to flush all pending messages via this ChannelOutboundInvoker.
public ChannelHandler	handler() The `ChannelHandler` that is bound this `ChannelHandlerContext`.
public boolean	isRemoved() Return `true` if the `ChannelHandler` which belongs to this context was removed from the `ChannelPipeline`.
public String	name() The unique name of the `ChannelHandlerContext`.The name was used when then `ChannelHandler` was added to the `ChannelPipeline`.
public ChannelPipeline	pipeline() Return the assigned `ChannelPipeline`
public ChannelHandlerContext	read(ReadBufferAllocator The `ReadBufferAllocator` that should be used to allocate a `Buffer` if needed (for reading the data). readBufferAllocator) Redeclares io.netty5.channel.ChannelOutboundInvoker.read. Request to read data from the `Channel`, triggers an `ChannelHandler#channelRead(ChannelHandlerContext, Object)` event if data was read, and triggers a `channelReadComplete` event so the handler can decide to continue reading.
public ChannelHandlerContext	read() Redeclares io.netty5.channel.ChannelOutboundInvoker.read.

Method Detail

bufferAllocator	back to summary
public default BufferAllocator bufferAllocator() Return the assigned `BufferAllocator` which will be used to allocate `Buffer`s.

channel	back to summary
public default Channel channel() Return the `Channel` which is bound to the `ChannelHandlerContext`.

fireChannelActive back to summary

fireChannelActive	back to summary
public ChannelHandlerContext fireChannelActive() Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelActive. Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelActive. A `Channel` is active now, which means it is connected. This will result in having the `ChannelHandler#channelActive(ChannelHandlerContext)` method called of the next `ChannelHandler` contained in the `ChannelPipeline` of the `Channel`. Annotations @Override

public ChannelHandlerContext fireChannelActive()

Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelActive.

Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelActive.

A Channel is active now, which means it is connected. This will result in having the ChannelHandler#channelActive(ChannelHandlerContext) method called of the next ChannelHandler contained in the ChannelPipeline of the Channel.

Annotations

@Override

fireChannelExceptionCaught back to summary

fireChannelExceptionCaught	back to summary
public ChannelHandlerContext fireChannelExceptionCaught(Throwable cause) Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelExceptionCaught. Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelExceptionCaught. A `Channel` received an `Throwable` in one of its inbound operations. This will result in having the `ChannelHandler#channelExceptionCaught(ChannelHandlerContext, Throwable)` method called of the next `ChannelHandler` contained in the `ChannelPipeline` of the `Channel`. Annotations @Override

public ChannelHandlerContext fireChannelExceptionCaught(Throwable cause)

Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelExceptionCaught.

Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelExceptionCaught.

A Channel received an Throwable in one of its inbound operations. This will result in having the ChannelHandler#channelExceptionCaught(ChannelHandlerContext, Throwable) method called of the next ChannelHandler contained in the ChannelPipeline of the Channel.

Annotations

@Override

fireChannelInactive back to summary

fireChannelInactive	back to summary
public ChannelHandlerContext fireChannelInactive() Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelInactive. Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelInactive. A `Channel` is inactive now, which means it is closed. This will result in having the `ChannelHandler#channelInactive(ChannelHandlerContext)` method called of the next `ChannelHandler` contained in the `ChannelPipeline` of the `Channel`. Annotations @Override

public ChannelHandlerContext fireChannelInactive()

Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelInactive.

Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelInactive.

A Channel is inactive now, which means it is closed. This will result in having the ChannelHandler#channelInactive(ChannelHandlerContext) method called of the next ChannelHandler contained in the ChannelPipeline of the Channel.

Annotations

@Override

fireChannelInboundEvent back to summary

fireChannelInboundEvent	back to summary
public ChannelHandlerContext fireChannelInboundEvent(Object evt) Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelInboundEvent. Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelInboundEvent. A `Channel` received a custom defined inbound event. This will result in having the `ChannelHandler#channelInboundEvent(ChannelHandlerContext, Object)` method called of the next `ChannelHandler` contained in the `ChannelPipeline` of the `Channel`. Annotations @Override

public ChannelHandlerContext fireChannelInboundEvent(Object evt)

Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelInboundEvent.

Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelInboundEvent.

A Channel received a custom defined inbound event. This will result in having the ChannelHandler#channelInboundEvent(ChannelHandlerContext, Object) method called of the next ChannelHandler contained in the ChannelPipeline of the Channel.

Annotations

@Override

fireChannelRead back to summary

fireChannelRead	back to summary
public ChannelHandlerContext fireChannelRead(Object msg) Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelRead. Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelRead. A `Channel` received a message. This will result in having the `ChannelHandler#channelRead(ChannelHandlerContext, Object)` method called of the next `ChannelHandler` contained in the `ChannelPipeline` of the `Channel`. Annotations @Override

public ChannelHandlerContext fireChannelRead(Object msg)

Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelRead.

Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelRead.

A Channel received a message. This will result in having the ChannelHandler#channelRead(ChannelHandlerContext, Object) method called of the next ChannelHandler contained in the ChannelPipeline of the Channel.

Annotations

@Override

fireChannelReadComplete back to summary

fireChannelReadComplete	back to summary
public ChannelHandlerContext fireChannelReadComplete() Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelReadComplete. Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelReadComplete. Triggers an `ChannelHandler#channelReadComplete(ChannelHandlerContext)` event to the next `ChannelHandler` in the `ChannelPipeline`. Annotations @Override

public ChannelHandlerContext fireChannelReadComplete()

Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelReadComplete.

Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelReadComplete.

Triggers an ChannelHandler#channelReadComplete(ChannelHandlerContext) event to the next ChannelHandler in the ChannelPipeline.

Annotations

@Override

fireChannelRegistered back to summary

fireChannelRegistered	back to summary
public ChannelHandlerContext fireChannelRegistered() Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelRegistered. Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelRegistered. A `Channel` was registered to its `EventLoop`. This will result in having the `ChannelHandler#channelRegistered(ChannelHandlerContext)` method called of the next `ChannelHandler` contained in the `ChannelPipeline` of the `Channel`. Annotations @Override

public ChannelHandlerContext fireChannelRegistered()

Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelRegistered.

Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelRegistered.

A Channel was registered to its EventLoop. This will result in having the ChannelHandler#channelRegistered(ChannelHandlerContext) method called of the next ChannelHandler contained in the ChannelPipeline of the Channel.

Annotations

@Override

fireChannelShutdown back to summary

fireChannelShutdown	back to summary
public ChannelHandlerContext fireChannelShutdown(ChannelShutdownDirection direction) Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelShutdown. Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelShutdown. A `Channel` was shutdown in a specific direction. This will result in having the `ChannelHandler#channelShutdown(ChannelHandlerContext, ChannelShutdownDirection)` method called of the next `ChannelHandler` contained in the `ChannelPipeline` of the `Channel`. Annotations @Override

public ChannelHandlerContext fireChannelShutdown(ChannelShutdownDirection direction)

Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelShutdown.

Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelShutdown.

A Channel was shutdown in a specific direction. This will result in having the ChannelHandler#channelShutdown(ChannelHandlerContext, ChannelShutdownDirection) method called of the next ChannelHandler contained in the ChannelPipeline of the Channel.

Annotations

@Override

fireChannelUnregistered back to summary

fireChannelUnregistered	back to summary
public ChannelHandlerContext fireChannelUnregistered() Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelUnregistered. Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelUnregistered. A `Channel` was unregistered from its `EventLoop`. This will result in having the `ChannelHandler#channelUnregistered(ChannelHandlerContext)` method called of the next `ChannelHandler` contained in the `ChannelPipeline` of the `Channel`. Annotations @Override

public ChannelHandlerContext fireChannelUnregistered()

Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelUnregistered.

Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelUnregistered.

A Channel was unregistered from its EventLoop. This will result in having the ChannelHandler#channelUnregistered(ChannelHandlerContext) method called of the next ChannelHandler contained in the ChannelPipeline of the Channel.

Annotations

@Override

fireChannelWritabilityChanged back to summary

fireChannelWritabilityChanged	back to summary
public ChannelHandlerContext fireChannelWritabilityChanged() Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelWritabilityChanged. Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelWritabilityChanged. Triggers an `ChannelHandler#channelWritabilityChanged(ChannelHandlerContext)` event to the next `ChannelHandler` in the `ChannelPipeline`. Annotations @Override

public ChannelHandlerContext fireChannelWritabilityChanged()

Redeclares io.netty5.channel.ChannelInboundInvoker.fireChannelWritabilityChanged.

Doc from io.netty5.channel.ChannelInboundInvoker.fireChannelWritabilityChanged.

Triggers an ChannelHandler#channelWritabilityChanged(ChannelHandlerContext) event to the next ChannelHandler in the ChannelPipeline.

Annotations

@Override

flush	back to summary
public ChannelHandlerContext flush() Redeclares io.netty5.channel.ChannelOutboundInvoker.flush. Doc from io.netty5.channel.ChannelOutboundInvoker.flush. Request to flush all pending messages via this ChannelOutboundInvoker. Annotations @Override

flush

back to summary

public ChannelHandlerContext flush()

Redeclares io.netty5.channel.ChannelOutboundInvoker.flush.

Doc from io.netty5.channel.ChannelOutboundInvoker.flush.

Request to flush all pending messages via this ChannelOutboundInvoker.

Annotations

@Override

handler	back to summary
public ChannelHandler handler() The `ChannelHandler` that is bound this `ChannelHandlerContext`.

isRemoved	back to summary
public boolean isRemoved() Return `true` if the `ChannelHandler` which belongs to this context was removed from the `ChannelPipeline`.

name	back to summary
public String name() The unique name of the `ChannelHandlerContext`.The name was used when then `ChannelHandler` was added to the `ChannelPipeline`. This name can also be used to access the registered `ChannelHandler` from the `ChannelPipeline`.

pipeline	back to summary
public ChannelPipeline pipeline() Return the assigned `ChannelPipeline`

read back to summary

read	back to summary
public ChannelHandlerContext read(ReadBufferAllocator readBufferAllocator) Redeclares io.netty5.channel.ChannelOutboundInvoker.read. Doc from io.netty5.channel.ChannelOutboundInvoker.read. Request to read data from the `Channel`, triggers an `ChannelHandler#channelRead(ChannelHandlerContext, Object)` event if data was read, and triggers a `channelReadComplete` event so the handler can decide to continue reading. If there's a pending read operation already, this method does nothing. This will result in having the `ChannelHandler#read(ChannelHandlerContext, ReadBufferAllocator)` method called of the next `ChannelHandler` contained in the `ChannelPipeline` of the `Channel`. Parameters readBufferAllocator:ReadBufferAllocator The `ReadBufferAllocator` that should be used to allocate a `Buffer` if needed (for reading the data). Annotations @Override

public ChannelHandlerContext read(ReadBufferAllocator readBufferAllocator)

Redeclares io.netty5.channel.ChannelOutboundInvoker.read.

Doc from io.netty5.channel.ChannelOutboundInvoker.read.

Request to read data from the Channel, triggers an ChannelHandler#channelRead(ChannelHandlerContext, Object) event if data was read, and triggers a channelReadComplete event so the handler can decide to continue reading. If there's a pending read operation already, this method does nothing.

This will result in having the ChannelHandler#read(ChannelHandlerContext, ReadBufferAllocator) method called of the next ChannelHandler contained in the ChannelPipeline of the Channel.

Parameters