Netty 4.1.107.Final · io.netty.handler.codec.MessageToByteEncoder

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);
        }
    }

Modifier and Type	Field and Description
private final TypeParameterMatcher	matcher
private final boolean	preferDirect

Constructor Summary

Access	Constructor and Description
protected	MessageToByteEncoder() see `MessageToByteEncoder(boolean)` with `true` as boolean parameter.
protected	MessageToByteEncoder(Class<? extends I> outboundMessageType) see `MessageToByteEncoder(Class, boolean)` with `true` as boolean value.
protected	MessageToByteEncoder(boolean `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. 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> The type of messages to match outboundMessageType, boolean `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. preferDirect) Create a new instance

Method Summary

Modifier and Type	Method and Description
public boolean	acceptOutboundMessage(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 the `ChannelHandlerContext` which this `MessageToByteEncoder` belongs to ctx, I the message to encode msg, ByteBuf the `ByteBuf` into which the encoded message will be written out) Encode a message into a `ByteBuf`.
protected boolean	isPreferDirect()
public void	write(ChannelHandlerContext the `ChannelHandlerContext` for which the write operation is made ctx, Object the message to write msg, ChannelPromise the `ChannelPromise` to notify once the operation completes promise) Overrides io.netty.channel.ChannelOutboundHandlerAdapter.write. Implements io.netty.channel.ChannelOutboundHandler.write. Calls `ChannelHandlerContext#write(Object, ChannelPromise)` to forward to the next `ChannelOutboundHandler` in the `ChannelPipeline`.

Inherited from io.netty.channel.ChannelOutboundHandlerAdapter:: bind close connect deregister disconnect flush read

Field Detail

matcher	back to summary
private final TypeParameterMatcher matcher

preferDirect	back to summary
private final boolean preferDirect

Constructor Detail

MessageToByteEncoder	back to summary
protected MessageToByteEncoder() see `MessageToByteEncoder(boolean)` with `true` as boolean parameter.

MessageToByteEncoder	back to summary
protected MessageToByteEncoder(Class<? extends I> outboundMessageType) see `MessageToByteEncoder(Class, boolean)` with `true` as boolean value.

MessageToByteEncoder back to summary

MessageToByteEncoder	back to summary
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:boolean `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.

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:boolean: 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 back to summary

MessageToByteEncoder	back to summary
protected MessageToByteEncoder(Class<? extends I> outboundMessageType, boolean preferDirect) Create a new instance Parameters outboundMessageType:Class<? extends I> The type of messages to match preferDirect:boolean `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.

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

Create a new instance

Parameters

outboundMessageType:Class<? extends I>: The type of messages to match
preferDirect:boolean: 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	back to summary
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`.

allocateBuffer	back to summary
protected ByteBuf allocateBuffer(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`.

encode back to summary

encode	back to summary
protected abstract void encode(ChannelHandlerContext ctx, I msg, 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:ChannelHandlerContext the `ChannelHandlerContext` which this `MessageToByteEncoder` belongs to msg:I the message to encode out:ByteBuf the `ByteBuf` into which the encoded message will be written Exceptions Exception: is thrown if an error occurs

protected abstract void encode(ChannelHandlerContext ctx, I msg, 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:ChannelHandlerContext: the ChannelHandlerContext which this MessageToByteEncoder belongs to
msg:I: the message to encode
out:ByteBuf: the ByteBuf into which the encoded message will be written

Exceptions

Exception:: is thrown if an error occurs

isPreferDirect	back to summary
protected boolean isPreferDirect()

write back to summary

write	back to summary
public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception Overrides io.netty.channel.ChannelOutboundHandlerAdapter.write. Implements io.netty.channel.ChannelOutboundHandler.write. Doc from io.netty.channel.ChannelOutboundHandlerAdapter.write. Calls `ChannelHandlerContext#write(Object, ChannelPromise)` to forward to the next `ChannelOutboundHandler` in the `ChannelPipeline`. Sub-classes may override this method to change behavior. Parameters ctx:ChannelHandlerContext Doc from io.netty.channel.ChannelOutboundHandler.write. the `ChannelHandlerContext` for which the write operation is made msg:Object Doc from io.netty.channel.ChannelOutboundHandler.write. the message to write promise:ChannelPromise Doc from io.netty.channel.ChannelOutboundHandler.write. the `ChannelPromise` to notify once the operation completes Annotations @Override Exceptions Exception: Doc from io.netty.channel.ChannelOutboundHandler.write. thrown if an error occurs