io.netty.handler.stream

Class ChunkedWriteHandler

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelInboundHandlerAdapter

io.netty.channel.ChannelDuplexHandler

io.netty.handler.stream.ChunkedWriteHandler

All Implemented Interfaces:

ChannelHandler, ChannelInboundHandler, ChannelOutboundHandler

public class ChunkedWriteHandler
extends ChannelDuplexHandler

A ChannelHandler that adds support for writing a large data stream asynchronously neither spending a lot of memory nor getting OutOfMemoryError. Large data streaming such as file transfer requires complicated state management in a ChannelHandler implementation. ChunkedWriteHandler manages such complicated states so that you can send a large data stream without difficulties.

To use ChunkedWriteHandler in your application, you have to insert a new ChunkedWriteHandler instance:

 ChannelPipeline p = ...;
 p.addLast("streamer", new ChunkedWriteHandler());
 p.addLast("handler", new MyHandler());
 

Once inserted, you can write a ChunkedInput so that the ChunkedWriteHandler can pick it up and fetch the content of the stream chunk by chunk and write the fetched chunk downstream:

 Channel ch = ...;
 ch.write(new ChunkedFile(new File("video.mkv"));
 

Sending a stream which generates a chunk intermittently

Some ChunkedInput generates a chunk on a certain event or timing. Such ChunkedInput implementation often returns null on ChunkedInput.readChunk(ChannelHandlerContext), resulting in the indefinitely suspended transfer. To resume the transfer when a new chunk is available, you have to call resumeTransfer().

Nested Class Summary

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

ChannelHandler.Sharable

Constructor Summary

Constructors

Constructor and Description
ChunkedWriteHandler()
ChunkedWriteHandler(int maxPendingWrites)

Method Summary

Methods

Modifier and Type	Method and Description
void	channelInactive(ChannelHandlerContext ctx) Calls ChannelHandlerContext.fireChannelInactive() to forward to the next ChannelInboundHandler in the ChannelPipeline.
void	flush(ChannelHandlerContext ctx) Calls ChannelHandlerContext.flush() to forward to the next ChannelOutboundHandler in the ChannelPipeline.
void	handlerAdded(ChannelHandlerContext ctx) Do nothing by default, sub-classes may override this method.
void	read(ChannelHandlerContext ctx) Calls ChannelOutboundInvoker.read() to forward to the next ChannelOutboundHandler in the ChannelPipeline.
void	resumeTransfer() Continues to fetch the chunks from the input.
void	write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) Calls ChannelOutboundInvoker.write(Object, ChannelPromise) to forward to the next ChannelOutboundHandler in the ChannelPipeline.

Methods inherited from class io.netty.channel.ChannelDuplexHandler

bind, close, connect, deregister, disconnect

Methods inherited from class io.netty.channel.ChannelInboundHandlerAdapter

channelActive, channelRead, channelReadComplete, channelRegistered, channelUnregistered, channelWritabilityChanged, userEventTriggered

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

exceptionCaught, handlerRemoved

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.netty.channel.ChannelHandler

exceptionCaught, handlerRemoved

Constructor Detail

ChunkedWriteHandler

public ChunkedWriteHandler()

ChunkedWriteHandler

public ChunkedWriteHandler(int maxPendingWrites)

Method Detail

handlerAdded

public void handlerAdded(ChannelHandlerContext ctx)
                  throws Exception

Description copied from class: ChannelHandlerAdapter

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

Specified by:

handlerAdded in interface ChannelHandler

Overrides:

handlerAdded in class ChannelHandlerAdapter

Throws:

Exception

resumeTransfer

public void resumeTransfer()

Continues to fetch the chunks from the input.

read

public void read(ChannelHandlerContext ctx)

Description copied from class: ChannelDuplexHandler

Calls ChannelOutboundInvoker.read() to forward to the next ChannelOutboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

read in interface ChannelOutboundHandler

Overrides:

read in class ChannelDuplexHandler

write

public void write(ChannelHandlerContext ctx,
         Object msg,
         ChannelPromise promise)
           throws Exception

Description copied from class: ChannelDuplexHandler

Calls ChannelOutboundInvoker.write(Object, ChannelPromise) to forward to the next ChannelOutboundHandler in the ChannelPipeline. Sub-classes may override this method to change behavior.

Specified by:

write in interface ChannelOutboundHandler

Overrides:

write in class ChannelDuplexHandler

Parameters:

ctx - the ChannelHandlerContext for which the write operation is made

msg - the message to write

promise - the ChannelPromise to notify once the operation completes

Throws:

Exception - thrown if an error accour

flush

public void flush(ChannelHandlerContext ctx)
           throws Exception

Description copied from class: ChannelDuplexHandler

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

Specified by:

flush in interface ChannelOutboundHandler

Overrides:

flush in class ChannelDuplexHandler

Parameters:

ctx - the ChannelHandlerContext for which the flush operation is made

Throws:

Exception - thrown if an error accour

channelInactive

public void channelInactive(ChannelHandlerContext ctx)
                     throws Exception

Description copied from class: ChannelInboundHandlerAdapter

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

Specified by:

channelInactive in interface ChannelInboundHandler

Overrides:

channelInactive in class ChannelInboundHandlerAdapter

Throws:

Exception