Package 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:
io.netty.channel.ChannelHandler, io.netty.channel.ChannelOutboundHandler
Direct Known Subclasses:
BrotliEncoder, Bzip2Encoder, CompatibleMarshallingEncoder, CompatibleObjectEncoder, FastLzFrameEncoder, Lz4FrameEncoder, LzfEncoder, LzmaFrameEncoder, MarshallingEncoder, ObjectEncoder, ProtobufVarint32LengthFieldPrepender, SnappyFrameEncoder, ZlibEncoder, ZstdEncoder
public abstract class MessageToByteEncoder<I> extends io.netty.channel.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

    io.netty.channel.ChannelHandler.Sharable

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    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(Class<? extends I> outboundMessageType)
    see MessageToByteEncoder(Class, boolean) with true as boolean value.
    protected
    MessageToByteEncoder(Class<? extends I> outboundMessageType, boolean preferDirect)
    Create a new instance

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    acceptOutboundMessage(Object msg)
    Returns true if the given message should be handled.
    protected io.netty.buffer.ByteBuf
    allocateBuffer(io.netty.channel.ChannelHandlerContext ctx, I msg, boolean preferDirect)
    Allocate a ByteBuf which will be used as argument of encode(ChannelHandlerContext, I, ByteBuf).
    protected abstract void
    encode(io.netty.channel.ChannelHandlerContext ctx, I msg, io.netty.buffer.ByteBuf out)
    Encode a message into a ByteBuf.
    protected boolean
    isPreferDirect()
     
    void
    write(io.netty.channel.ChannelHandlerContext ctx, Object msg, io.netty.channel.ChannelPromise promise)
     

    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 Details

    • MessageToByteEncoder

      protected MessageToByteEncoder()
      see MessageToByteEncoder(boolean) with true as boolean parameter.

    • MessageToByteEncoder

      protected MessageToByteEncoder(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(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 Details

    • acceptOutboundMessage

      public boolean acceptOutboundMessage(Object msg) throws Exception
      Returns true if the given message should be handled. If false it will be passed to the next ChannelOutboundHandler in the ChannelPipeline.
      Throws:
      Exception

    • write

      public void write(io.netty.channel.ChannelHandlerContext ctx, Object msg, io.netty.channel.ChannelPromise promise) throws Exception
      Specified by:
      write in interface io.netty.channel.ChannelOutboundHandler
      Overrides:
      write in class io.netty.channel.ChannelOutboundHandlerAdapter
      Throws:
      Exception

    • allocateBuffer

      protected io.netty.buffer.ByteBuf allocateBuffer(io.netty.channel.ChannelHandlerContext ctx, I msg, boolean preferDirect) throws 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:
      Exception

    • encode

      protected abstract void encode(io.netty.channel.ChannelHandlerContext ctx, I msg, io.netty.buffer.ByteBuf out) throws 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:
      Exception - is thrown if an error occurs

    • isPreferDirect

      protected boolean isPreferDirect()