io.netty.handler.codec

Class MessageToByteEncoder<I>

java.lang.Object

io.netty.channel.ChannelHandlerAdapter

io.netty.channel.ChannelOutboundHandlerAdapter

io.netty.handler.codec.MessageToByteEncoder<I>

All Implemented Interfaces:

ChannelHandler, ChannelOutboundHandler

Direct Known Subclasses:

CompatibleMarshallingEncoder, CompatibleObjectEncoder, LengthFieldPrepender, MarshallingEncoder, ObjectEncoder, ProtobufVarint32LengthFieldPrepender, SnappyFramedEncoder, SocksMessageEncoder, ZlibEncoder

public abstract class MessageToByteEncoder<I>
extends ChannelOutboundHandlerAdapter

ChannelOutboundHandlerAdapter which encodes message in a stream-like fashion from one message to an ByteBuf. Example implementation which encodes Integers to a ByteBuf.

     public class IntegerEncoder extends MessageToByteEncoder<Integer> {
          @Override
         public void encode(ChannelHandlerContext ctx, Integer msg, ByteBuf out)
                 throws Exception {
             out.writeInt(msg);
         }
     }
 

Nested Class Summary

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

ChannelHandler.Sharable

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	MessageToByteEncoder() see MessageToByteEncoder(boolean) with true as boolean parameter.
protected	MessageToByteEncoder(boolean preferDirect) Create a new instance which will try to detect the types to match out of the type parameter of the class.
protected	MessageToByteEncoder(java.lang.Class<? extends I> outboundMessageType) see MessageToByteEncoder(Class, boolean) with true as boolean value.
protected	MessageToByteEncoder(java.lang.Class<? extends I> outboundMessageType, boolean preferDirect) Create a new instance

Method Summary

Modifier and Type	Method and Description
boolean	acceptOutboundMessage(java.lang.Object msg) Returns true if the given message should be handled.
protected ByteBuf	allocateBuffer(ChannelHandlerContext ctx, I msg, boolean preferDirect) Allocate a ByteBuf which will be used as argument of #encode(ChannelHandlerContext, I, ByteBuf).
protected abstract void	encode(ChannelHandlerContext ctx, I msg, ByteBuf out) Encode a message into a ByteBuf.
void	write(ChannelHandlerContext ctx, java.lang.Object msg, ChannelPromise promise) Calls ChannelHandlerContext.write(Object, ChannelPromise) to forward to the next ChannelOutboundHandler in the ChannelPipeline.

Methods inherited from class io.netty.channel.ChannelOutboundHandlerAdapter

bind, close, connect, deregister, disconnect, flush, read

Methods inherited from class io.netty.channel.ChannelHandlerAdapter

ensureNotSharable, exceptionCaught, handlerAdded, handlerRemoved, isSharable

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, handlerAdded, handlerRemoved

Constructor Detail

MessageToByteEncoder

protected MessageToByteEncoder()

see MessageToByteEncoder(boolean) with true as boolean parameter.

MessageToByteEncoder

protected MessageToByteEncoder(java.lang.Class<? extends I> outboundMessageType)

see MessageToByteEncoder(Class, boolean) with true as boolean value.

MessageToByteEncoder

protected MessageToByteEncoder(boolean preferDirect)

Create a new instance which will try to detect the types to match out of the type parameter of the class.

Parameters:

preferDirect - true if a direct ByteBuf should be tried to be used as target for the encoded messages. If false is used it will allocate a heap ByteBuf, which is backed by an byte array.

MessageToByteEncoder

protected MessageToByteEncoder(java.lang.Class<? extends I> outboundMessageType,
                               boolean preferDirect)

Create a new instance

Parameters:

outboundMessageType - The type of messages to match

preferDirect - true if a direct ByteBuf should be tried to be used as target for the encoded messages. If false is used it will allocate a heap ByteBuf, which is backed by an byte array.

Method Detail

acceptOutboundMessage

public boolean acceptOutboundMessage(java.lang.Object msg)
                              throws java.lang.Exception

Returns true if the given message should be handled. If false it will be passed to the next ChannelOutboundHandler in the ChannelPipeline.

Throws:

java.lang.Exception

write

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

Description copied from class: ChannelOutboundHandlerAdapter

Calls ChannelHandlerContext.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 ChannelOutboundHandlerAdapter

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:

java.lang.Exception - thrown if an error occurs

allocateBuffer

protected ByteBuf allocateBuffer(ChannelHandlerContext ctx,
                                 I msg,
                                 boolean preferDirect)
                          throws java.lang.Exception

Allocate a ByteBuf which will be used as argument of #encode(ChannelHandlerContext, I, ByteBuf). Sub-classes may override this method to return ByteBuf with a perfect matching initialCapacity.

Throws:

java.lang.Exception

encode

protected abstract void encode(ChannelHandlerContext ctx,
                               I msg,
                               ByteBuf out)
                        throws java.lang.Exception

Encode a message into a ByteBuf. This method will be called for each written message that can be handled by this encoder.

Parameters:

ctx - the ChannelHandlerContext which this MessageToByteEncoder belongs to

msg - the message to encode

out - the ByteBuf into which the encoded message will be written

Throws:

java.lang.Exception - is thrown if an error occurs