Package io.netty.channel

Class ChannelInitializer<C extends Channel>

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.channel.ChannelInitializer<C>

Type Parameters:

C - A sub-type of Channel

All Implemented Interfaces:

ChannelHandler, ChannelInboundHandler

Direct Known Subclasses:

Http3PushStreamClientInitializer, Http3PushStreamServerInitializer, Http3RequestStreamInitializer

@Sharable
public abstract class ChannelInitializer<C extends Channel>
extends ChannelInboundHandlerAdapter

A special ChannelInboundHandler which offers an easy way to initialize a Channel once it was registered to its EventLoop. Implementations are most often used in the context of AbstractBootstrap.handler(ChannelHandler) , AbstractBootstrap.handler(ChannelHandler) and ServerBootstrap.childHandler(ChannelHandler) to setup the ChannelPipeline of a Channel.

 public class MyChannelInitializer extends ChannelInitializer {
     public void initChannel(Channel channel) {
         channel.pipeline().addLast("myHandler", new MyHandler());
     }
 }

 ServerBootstrap bootstrap = ...;
 ...
 bootstrap.childHandler(new MyChannelInitializer());
 ...
 

Be aware that this class is marked as ChannelHandler.Sharable and so the implementation must be safe to be re-used.

Nested Class Summary

Nested classes/interfaces inherited from interface io.netty.channel.ChannelHandler

ChannelHandler.Sharable

Constructor Summary

Constructors

Constructor	Description
ChannelInitializer()

Method Summary

Modifier and Type	Method	Description
void	channelRegistered(ChannelHandlerContext ctx)	Calls ChannelHandlerContext.fireChannelRegistered() to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	exceptionCaught(ChannelHandlerContext ctx, java.lang.Throwable cause)	Handle the Throwable by logging and closing the Channel.
void	handlerAdded(ChannelHandlerContext ctx)	Do nothing by default, sub-classes may override this method.
void	handlerRemoved(ChannelHandlerContext ctx)	Do nothing by default, sub-classes may override this method.
protected abstract void	initChannel(C ch)	This method will be called once the Channel was registered.

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelActive, channelInactive, channelRead, channelReadComplete, channelUnregistered, channelWritabilityChanged, userEventTriggered

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, isSharable

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ChannelInitializer

public ChannelInitializer()

Method Detail

initChannel

protected abstract void initChannel(C ch)
                             throws java.lang.Exception

This method will be called once the Channel was registered. After the method returns this instance will be removed from the ChannelPipeline of the Channel.

Parameters:

ch - the Channel which was registered.

Throws:

java.lang.Exception - is thrown if an error occurs. In that case it will be handled by exceptionCaught(ChannelHandlerContext, Throwable) which will by default close the Channel.

channelRegistered

public final void channelRegistered(ChannelHandlerContext ctx)
                             throws java.lang.Exception

Description copied from class: ChannelInboundHandlerAdapter

Calls ChannelHandlerContext.fireChannelRegistered() to forward to the next ChannelInboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

channelRegistered in interface ChannelInboundHandler

Overrides:

channelRegistered in class ChannelInboundHandlerAdapter

Throws:

java.lang.Exception

exceptionCaught

public void exceptionCaught(ChannelHandlerContext ctx,
                            java.lang.Throwable cause)
                     throws java.lang.Exception

Handle the Throwable by logging and closing the Channel. Sub-classes may override this.

Specified by:

exceptionCaught in interface ChannelHandler

Specified by:

exceptionCaught in interface ChannelInboundHandler

Overrides:

exceptionCaught in class ChannelInboundHandlerAdapter

Throws:

java.lang.Exception

handlerAdded

public void handlerAdded(ChannelHandlerContext ctx)
                  throws java.lang.Exception

Do nothing by default, sub-classes may override this method. If override this method ensure you call super!

Specified by:

handlerAdded in interface ChannelHandler

Overrides:

handlerAdded in class ChannelHandlerAdapter

Throws:

java.lang.Exception

handlerRemoved

public void handlerRemoved(ChannelHandlerContext ctx)
                    throws java.lang.Exception

Description copied from class: ChannelHandlerAdapter

Do nothing by default, sub-classes may override this method.

Specified by:

handlerRemoved in interface ChannelHandler

Overrides:

handlerRemoved in class ChannelHandlerAdapter

Throws:

java.lang.Exception