io.netty.channel.ChannelHandlerContext Maven / Gradle / Ivy
/*
* Copyright 2012 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.channel;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufAllocator;
import io.netty.util.Attribute;
import io.netty.util.AttributeKey;
import io.netty.util.AttributeMap;
import io.netty.util.concurrent.EventExecutor;
/**
* Enables a {@link ChannelHandler} to interact with its {@link ChannelPipeline}
* and other handlers. Among other things a handler can notify the next {@link ChannelHandler} in the
* {@link ChannelPipeline} as well as modify the {@link ChannelPipeline} it belongs to dynamically.
*
* Notify
*
* You can notify the closest handler in the same {@link ChannelPipeline} by calling one of the various methods
* provided here.
*
* Please refer to {@link ChannelPipeline} to understand how an event flows.
*
* Modifying a pipeline
*
* You can get the {@link ChannelPipeline} your handler belongs to by calling
* {@link #pipeline()}. A non-trivial application could insert, remove, or
* replace handlers in the pipeline dynamically at runtime.
*
* Retrieving for later use
*
* You can keep the {@link ChannelHandlerContext} for later use, such as
* triggering an event outside the handler methods, even from a different thread.
*
* public class MyHandler extends {@link ChannelDuplexHandler} {
*
* private {@link ChannelHandlerContext} ctx;
*
* public void beforeAdd({@link ChannelHandlerContext} ctx) {
* this.ctx = ctx;
* }
*
* public void login(String username, password) {
* ctx.write(new LoginMessage(username, password));
* }
* ...
* }
*
*
* Storing stateful information
*
* {@link #attr(AttributeKey)} allow you to
* store and access stateful information that is related with a {@link ChannelHandler} / {@link Channel} and its
* context. Please refer to {@link ChannelHandler} to learn various recommended
* ways to manage stateful information.
*
* A handler can have more than one {@link ChannelHandlerContext}
*
* Please note that a {@link ChannelHandler} instance can be added to more than
* one {@link ChannelPipeline}. It means a single {@link ChannelHandler}
* instance can have more than one {@link ChannelHandlerContext} and therefore
* the single instance can be invoked with different
* {@link ChannelHandlerContext}s if it is added to one or more {@link ChannelPipeline}s more than once.
* Also note that a {@link ChannelHandler} that is supposed to be added to multiple {@link ChannelPipeline}s should
* be marked as {@link io.netty.channel.ChannelHandler.Sharable}.
*
* Additional resources worth reading
*
* Please refer to the {@link ChannelHandler}, and
* {@link ChannelPipeline} to find out more about inbound and outbound operations,
* what fundamental differences they have, how they flow in a pipeline, and how to handle
* the operation in your application.
*/
public interface ChannelHandlerContext extends AttributeMap, ChannelInboundInvoker, ChannelOutboundInvoker {
/**
* Return the {@link Channel} which is bound to the {@link ChannelHandlerContext}.
*/
Channel channel();
/**
* Returns the {@link EventExecutor} which is used to execute an arbitrary task.
*/
EventExecutor executor();
/**
* The unique name of the {@link ChannelHandlerContext}.The name was used when then {@link ChannelHandler}
* was added to the {@link ChannelPipeline}. This name can also be used to access the registered
* {@link ChannelHandler} from the {@link ChannelPipeline}.
*/
String name();
/**
* The {@link ChannelHandler} that is bound this {@link ChannelHandlerContext}.
*/
ChannelHandler handler();
/**
* Return {@code true} if the {@link ChannelHandler} which belongs to this context was removed
* from the {@link ChannelPipeline}. Note that this method is only meant to be called from with in the
* {@link EventLoop}.
*/
boolean isRemoved();
@Override
ChannelHandlerContext fireChannelRegistered();
@Override
ChannelHandlerContext fireChannelUnregistered();
@Override
ChannelHandlerContext fireChannelActive();
@Override
ChannelHandlerContext fireChannelInactive();
@Override
ChannelHandlerContext fireExceptionCaught(Throwable cause);
@Override
ChannelHandlerContext fireUserEventTriggered(Object evt);
@Override
ChannelHandlerContext fireChannelRead(Object msg);
@Override
ChannelHandlerContext fireChannelReadComplete();
@Override
ChannelHandlerContext fireChannelWritabilityChanged();
@Override
ChannelHandlerContext read();
@Override
ChannelHandlerContext flush();
/**
* Return the assigned {@link ChannelPipeline}
*/
ChannelPipeline pipeline();
/**
* Return the assigned {@link ByteBufAllocator} which will be used to allocate {@link ByteBuf}s.
*/
ByteBufAllocator alloc();
/**
* @deprecated Use {@link Channel#attr(AttributeKey)}
*/
@Deprecated
@Override
Attribute attr(AttributeKey key);
/**
* @deprecated Use {@link Channel#hasAttr(AttributeKey)}
*/
@Deprecated
@Override
boolean hasAttr(AttributeKey key);
}